mamografo ge alpha rt service manual.pdf

Performa, Alpha RT, Alpha IQ, Alpha ST, Alpha III

Service Manual

June

200

0 3

1687

-4A

M

PLACE FOR OPERATIONINSTRUCTIONS

PLACE FOR INSTALLATIONINSTRUCTIONS

FUNCTIONAL DESCRIPTION

PREVENTIVE MAINTENANCE

TROUBLESHOOTING ANDERROR MESSAGES

REPAIR INSTRUCTIONS

SCHEMATICS

SERVICE MANUAL FOR ALPHA IQ/RT/ST/III AND PERFORMA

Notes/Cautions/WarningsUpdate InformationService Manual Contents

COPYRIGHT 8 2000 by Instrumentarium Imaging

Documentation, trademark and the software are copyrighted with allrights reserved. Under the copyright laws the documentation may not becopied, photocopied, reproduced, translated, or reduced to any electronicmedium or machine readable form in whole or part, without the priorwritten permission of Instrumentarium Imaging.

The original language of this manual is English.

Instrumentarium Imaging reserves the right to revise this publication fromtime to time and to make changes in the content of it without obligation tonotify any person of such revision or changes.

Microsoft, MS-DOS and Windows are trademarks of MicrosoftCorporation in the United States of America and other countries.

MANUFACTURED BY: Instrumentarium CorporationImaging DivisionP.O.Box 20FIN-04301 TuusulaFINLANDTel. +358-10-394 6500Fax. +358-10-394 6501e-mail: [email protected]: http://www.instrumentarium.com/imaging

Performa, Alpha IQ, RT, ST, III Service Manual

31687 June 2000

NOTES/CAUTIONS/WARNINGS

NOTE! ONLY ENGINEERS TRAINED BY INSTRUMENTARIUM AREALLOWED TO SERVICE THE UNIT. PARTS INSTALLED BYNONTRAINED PERSONNEL CARRY NO WARRANTY!

CAUTION! ALWAYS CHECK FOR PROPER SEATING ON ALL THECONNECTORS LOCATED IN THE AREAS YOU HAVE WORKED.EQUIPMENT DAMAGE CAN RESULT IF POWER IS APPLIED OREXPOSURES MADE WITH IMPROPERLY SEATED CONNECTORS!

WARNING! ALWAYS INSTALL THE PROPER FUSES INTO THE UNIT.FAILURE TO DO SO JEOPARDIZES PATIENT, OPERATOR ANDEQUIPMENT SAFETY. (SEE TABLE IN REPAIR SECTION)!

WARNING! THIS UNIT HAS FLOATING GROUNDS. ALWAYS MAKE ALLSCOPE MEASUREMENTS DIFFERENTIALLY AND ALWAYS BECAREFUL WHEN SERVICING THE UNIT!

CAUTION! WHEN HANDLING CIRCUIT BOARDS, ALWAYS UTILIZEGROUND WRIST STRAPS OR GROUNDING KITS TO PREVENTDAMAGE TO THE "MOS" TYPE CHIPS. ALWAYS KEEP CIRCUITBOARDS IN A STATIC PROOF BAG.

WARNING! ALWAYS DISCONNECT THE UNIT FROM LINE SUPPLY BYREMOVING THE PLUG FROM WALL OUTLET BEFORE OPENINGTHE COVERS.

WARNING! THE X-RAY TUBE UTILIZES A BERYLLIUM WINDOW. DO NOTPERFORM ANY OPERATIONS ON BERYLLIUM WHICH PRODUCEDUST OR FUMES, SUCH AS GRINDING, GRIT BLASTING OR ACIDCLEANING. BERYLLIUM DUST OR FUMES ARE HIGHLY TOXICAND BREATHING THEM CAN RESULT IN SERIOUS PERSONALINJURY OR DEATH.

WARNING! THIS X-RAY UNIT MAY BE DANGEROUS TO PATIENT ANDOPERATOR UNLESS SAFE EXPOSURE FACTORS ANDINSTRUCTIONS ARE OBSERVED!

Service Manual Performa, Alpha IQ, RT, ST, III

June 2000 31687

UPDATE INFORMATION

From time to time, update sheets will be issued to bring your service manualup-to-date. For ease of updating, the new information will be page for page, orsection for section, replaceable. You will also get a new update table so youcan check the contents of your manual to verify you have the latestinformation. You can also check what has been changed from the previousrevision.

Version: Manual date: Details revisited:

31687-4AM May 2000 33892 ECS driver board ver.7.30

ECS Troubleshooting

Measurement of the feedbackcircuitry

31687-4AL January 2000 Section 7 / Schematics

Software block diagram 7.30

31687-4AK May 1998 Section 7 / Schematics

32305 AMD board ver. 3.0

32220 Inverter board ver. 1.3

32245 CPU board ver. 1.3

33270 SMD AEC board ver 1.1

33035 C&Z driver board ver 1.4

Software block diagram 7.29


31687 June 2000

31687-4AJ November 1996 Section 7 / Schematics

Main wiring diagram

Casopto board OPTIPOINT33280

AEC Display boardOPTIPOINT 33275

SMD AEC board OPTIPOINT33270

5V Power Supply board (OnlyST) 32962

Sensor board OPTIPOINT32735

31687-4AI October 1995 Details

31687-4AH February 1995 C&Z Drive Board (33035)

31687-4AG December 1994 SW 7.xx, New service programmenu

31687-4AF May - June 1994 New type generator

31687-4AE December 1993 SW 5.09, INF-mode, Print mode

31687-4AD February 1993 Details

31687-4AC February 1993 Details

31687-4AB March 1992 Section 7 (Bucky control)

31687-4AA March 1992 Section 7 (Pulse, Base, Powerboards)

31687-4A March 1992 New manual


31687 June 2000

TABLE OF CONTENTS

3 FUNCTIONAL DESCRIPTION .......................................................................... 3-1

3.1 SOFTWARE BLOCK DIAGRAM ........................................................... 3-13.2 KEYBOARD FUNCTIONS ...................................................................... 3-1

3.2.1 Main modes (nor-, SER- and Pr -mode)............................................ 3-1

3.2.2 Program (Pr) mode ........................................................................... 3-3

3.2.3 Service program menu...................................................................... 3-4

3.2.3.1 SETUP-mode (SUP and Par programs; see 3.1) .................... 3-7

3.2.3.2 Calibrations (see section 7 software block diagram) .............. 3-8

3.2.3.3 Diagnostics (see 3.1)........................................................... 3-10

3.2.3.4 Integrated Quality Control History...................................... 3-10

3.2.3.5 AEC adjustment parameters................................................ 3-11

3.3 USING THE SERIAL PORT IN FOR COMMUNICATION ............... 3-15

3.3.1 The Cable....................................................................................... 3-15

3.3.2 Communication protocol ................................................................ 3-16

3.3.3 Data formats................................................................................... 3-16

3.4 THEORY OF OPERATIONS................................................................. 3-19

3.4.1 Process controller ........................................................................... 3-19

3.4.1.1 The CPU BOARD .............................................................. 3-19

3.4.2 User interface ................................................................................. 3-21

3.4.2.1 Switch and microswitch reading.......................................... 3-21

3.4.2.2 Collimator lamp operation .................................................. 3-21

3.4.2.3 Cassette sensing CASOPTO BOARD................................. 3-22

3.4.2.4 Cassette holder sensing CSENSE BOARD ......................... 3-22

3.4.3 X-RAY GENERATION AND CONTROL .................................... 3-23

3.4.3.1 INVERTER BOARD.......................................................... 3-24

3.4.3.2 The high voltage unit .......................................................... 3-27

3.4.3.3 mA generation timing ......................................................... 3-28

3.4.3.4 FILAMENT CONTROL BOARD ...................................... 3-28

3.4.3.5 Anode motor drive AMD BOARD...................................... 3-32

3.4.3.6 Mains transformer............................................................... 3-32

3.4.3.7 Energy storage capacitor..................................................... 3-32

3.4.3.8 Motor phase shift capacitor................................................. 3-32


June 2000 31687

3.4.3.9 Tube housing assembly........................................................3-32

3.4.3.10 X-ray tube bias circuit (M101G)........................................3-32

3.4.4 Motor control..................................................................................3-34

3.4.4.1 Motor control - general........................................................3-34

3.4.4.2 C&Z DRIVER BOARD ......................................................3-34

3.4.4.3 Back up release ...................................................................3-36

3.4.4.4 Anode motor .......................................................................3-37

3.4.4.5 Bucky motor .......................................................................3-37

3.4.5 Automatic exposure control (AEC) .................................................3-38

3.4.5.1 AEC - general......................................................................3-38

3.4.5.2 The Detector .......................................................................3-38

3.4.5.3 AEC BOARD......................................................................3-38

3.4.5.4 The CPU .............................................................................3-39

3.5 DESCRIPTION OF CONTROL ELECTRONICS ................................3-40

3.5.1 Mains transformer and SUPPLY board ...........................................3-40

3.5.2 CPU board ......................................................................................3-40

3.5.3 DISPLAY BOARD.........................................................................3-42

3.5.4 C&Z-DRIVER BOARD .................................................................3-42

3.5.5 CD-BOARD ...................................................................................3-43

3.5.6 C-ARM CONTROL BOARD .........................................................3-43

3.5.7 C-ARM DISPLAY BOARD ...........................................................3-44

3.5.8 ECS DRIVER BOARD...................................................................3-44

4 PREVENTIVE MAINTENANCE........................................................................ 4-1

4.1 X-RAY TUBE PERFORMANCE CHECK.............................................. 4-1

4.1.1 Half-value layer (HVL) measurement .............................................. 4-1

4.1.2 Tube efficiency check on the cassette holder .................................... 4-2

4.1.3 Focal spot measurement procedure .................................................. 4-3

4.1.4 Image quality evaluation procedure.................................................. 4-5

4.1.5 Measurement of the feedback circuitry............................................. 4-7

4.2 AUTOMATIC EXPOSURE CONTROL EVALUATION ...................... 4-8

4.2.1 Quick AEC test ................................................................................ 4-8

4.2.3 Object thickness compensation ........................................................ 4-8

4.2.2 kV compensation ............................................................................4-10


31687 June 2000

4.3 MECHANICAL CHECKS...................................................................... 4-11

4.3.1 Compression system....................................................................... 4-11

4.3.2 C-arm rotation brake ...................................................................... 4-11

4.3.3 Column and carriage....................................................................... 4-11

4.3.4 Compression force checking........................................................... 4-11

4.3.5 Testing the x-ray field illumination................................................. 4-11

5 TROUBLESHOOTING & ERROR MESSAGES ............................................... 5-1

5.1 Error message chart................................................................................... 5-15.2 Useful information to have when calling for assistance............................ 5-25.3 E.01 Error message explanation................................................................ 5-35.4 E.02 Error message explanation................................................................ 5-4

5.4.1 Testing of the new Performa, Alpha generator.................................. 5-5

5.4.2 Testing of the old Alpha generator.................................................... 5-65.5 E.03 Error message explanation................................................................ 5-75.6 E.04 Error message explanation................................................................ 5-85.7 E.05 Error message explanation (software 5.08 and higher).................... 5-95.8 E.06 ERROR MESSAGE EXPLANATION............................................. 5-95.9 E.07 ERROR MESSAGE EXPLANATION............................................. 5-95.10 E.08 ERROR MESSAGE EXPLANATION........................................... 5-105.11 E.09 Error message explanation (PERFORMA, RT/IQ) ....................... 5-105.12 E.10 Error message explanation.............................................................. 5-105.13 E.11 Error message explanation.............................................................. 5-115.14 E.12 Error message explanation.............................................................. 5-115.15 E.r1 Error message explanation.............................................................. 5-115.16 E.r2 ERROR MESSAGE EXPLANATION ........................................... 5-115.17 E.r3 Error message explanation.............................................................. 5-115.18 E.r4 Error message explanation.............................................................. 5-125.19 E.r5 Error message explanation.............................................................. 5-125.20 S.Lo Error message explanation ............................................................. 5-125.21 C.Br Error message explanation (Software 7.27 and up)....................... 5-125.22 C.bu Error message explanation ............................................................. 5-125.23 C.CA Error message explanation............................................................ 5-135.24 C.Ch Error message explanation ............................................................ 5-135.25 C.Cn Error message explanation ............................................................ 5-145.26 C.Co Error message explanation............................................................. 5-145.27 C.ES Error message explanation............................................................. 5-145.28 C.PS Error message explanation............................................................. 5-145.29 C.dE Error message explanation............................................................. 5-155.30 O.FL Error message explanation ............................................................ 5-155.31 R.EL Error message explanation ............................................................ 5-155.32 R.ES Error message explanation............................................................. 5-165.33 (U.FL Error message explanation) not used ........................................... 5-165.34 S.YS (Software 7.27 and up).................................................................... 5-165.35 t.OF (Software 7.27 and up) .................................................................... 5-165.36 E.AF (Software 7.27 and up) ................................................................... 5-175.37 No power indications ............................................................................... 5-17


June 2000 31687

5.38 AEC Inoperative.......................................................................................5-175.39 Software diagnostic mode ........................................................................5-18

5.39.1 Entering Diagnostic Mode ..............................................................5-18

5.39.2 Error readout...................................................................................5-18

5.39.3 Switch and signal status display ......................................................5-19

5.40 SUPPLY VOLTAGES..............................................................................5-205.41 Grid lines...................................................................................................5-215.42 ECS Trouble shooting ..............................................................................5-22

6 REPAIR INSTRUCTIONS .................................................................................. 6-1

6.1 FUSE RATING / LOCATION CHART................................................... 6-16.2 COLUMN REPAIR................................................................................... 6-2

6.2.1 Tilt down the column ....................................................................... 6-2

6.2.2 Replacing the floor plate .................................................................. 6-2

6.2.3 Replacing the Z-motor ..................................................................... 6-3

6.2.4 Replacing the column cap ................................................................ 6-4

6.2.5 Replacing the mechanical stopper .................................................... 6-6

6.2.6 Replacing the wires.......................................................................... 6-6

6.2.7 Replacing the counterweight ............................................................ 6-7

6.3 POWER UNIT REPAIR........................................................................... 6-8

6.3.1 Removal and assembly of the rear cover .......................................... 6-8

6.3.2 Replacing the POWER / INVERTER board..................................... 6-8

6.3.3 Replacing other parts ....................................................................... 6-8

6.4 CARRIAGE REPAIR ............................................................................... 6-9

6.4.1 Removal and assembly of the side covers......................................... 6-9

6.4.2 Replacing the mains transformers..................................................... 6-9

6.4.3 Replacing the boards on the electronic plate....................................6-11

6.4.4 Replacing the SUPPLY board.........................................................6-11

6.4.5 Replacing the magnetic brake and its assembly ...............................6-12

6.4.6 Replacing the MGF DISPLAY board..............................................6-156.5 C-ARM REPAIR......................................................................................6-16

6.5.1 Removal and assembly of the C-arm covers ....................................6-16

6.5.2 Replacing the handgrips..................................................................6-16

6.5.3 Replacing the brake switch..............................................................6-16

6.5.4 Replacing the vertical drive control switch......................................6-16


31687 June 2000

6.5.5 Replacing the x-ray tube................................................................. 6-19

6.5.6 Replacing the high voltage unit ...................................................... 6-19

6.5.7 Replacing the AMD board.............................................................. 6-19

6.5.8 Replacing the compression motor................................................... 6-20

6.5.9 Replacing the compression system.................................................. 6-20

6.5.10 Replacing the compression thickness measurement potentiometer .. 6-20

6.5.11 Replacing the compression force measurement system (str. gages) . 6-20

6.5.12 Replacing the C-arm angulation measurement system (trim pot) .... 6-20

6.5.13 Replacing the cassette holder base cover ........................................ 6-23

6.5.14 Replacing the cassette holder base .................................................. 6-23

6.5.15 Replacing the collimator................................................................. 6-25

6.5.16 Replacing the light field bulb.......................................................... 6-25

6.5.17 Replacing the beam filter mechanism ............................................. 6-26

6.5.18 Replacing the compression display board ....................................... 6-26

6.5.19 Replacing the detector display board .............................................. 6-26

6.5.20 ECS repair ...................................................................................... 6-27

7 SCHEMATICS...................................................................................................... 7-1


31687 3-1 June 2000

PERFORMA, ALPHA SERVICE MANUAL CONTENTS

3 FUNCTIONAL DESCRIPTION

3.1 SOFTWARE BLOCK DIAGRAMPROGRAM VERSION 7.30 - See Section 7.23

3.2 KEYBOARD FUNCTIONS

3.2.1 Main modes (nor-, SER- and Pr -mode)

Exposure and other functions are possible only in main modes: nor and, SErmode. When the power is switched on to the device, the program is innor(=user)-mode, which functions as explained in this manual. InSEr(=service)-mode certain checks like the presence of the cassette holder,cassette, and diaphragm are bypassed so that service personnel can test thedevice without any delays. In service mode the kV and mAs display shows theAEC integration time in ms. If the AUTOREL button is pressed the timerdisplay shows the exposure time and the kV display shows the kV (Normallytimer display shows SEr).

NOTE! A cooling time of 5 to 55 sec. between exposure is implemented also in theservice mode. This will protect the unit from not being overloaded duringtesting.


June 2000 3-2 31687

The main functions achieved from the panel are listed below. The field"display" indicates what is seen in the display. '&' means simultaneouspressing.

KEY FUNCTION DISPLAY

kV+ Increase kV kV

kV- Decrease kV kV

mAs+ Increase mAs, not in AEC, go to IQC mAs

mAs- Decrease mAs, not in AEC, go to IQC mAs

DEN+ Increase exposure time by 10% DEN

DEN- Decrease exposure time by 10% DEN

AUTOREL Set automatic release on/offIn SEr-mode display exp.time

AUTOREL ledTIMER

AUTOEXP Switch between manual andAEC-modes

AUTO EXP led,leds for a,b,c

DEN-& kV- Switch between SEr- and nor-modeSwitch from AEC- to nor-mode

TIMER 'Ser'

DEN+ & - Enter pr- from nor - mode TIMER 'Pr'

DEN+ & - Enter service program menu from SEr-mode

mAs 'Pr' &kV '51'

DEN + & - Return to service mode from programmenu

TIMER 'Ser'


31687 3-3 June 2000

3.2.2 Program (Pr) mode

This mode can be entered from nor- and SEr-mode. Usually this is done whenthe unit is installed to adjust exposure parameters to the conditions at the site.The preset kV can be programmed in semi AEC mode from 23 to 35 kV forbucky and cassette tunnel, and 25-35 for magnification. The film/screencombinations (FI) are:

mAs-display film cassette/screen

FI1 Min - RE Min - R (Kodak/Kodak)

FI2 Microvision Min - R (Dupont/Kodak)

FI3 Min - RE Min - R/Medium

FI4 AGFA MR3+ AGFA MR Detail

FI5 Fuji M-1

HI-Mammo M1

Fuji MI-MA

FI6 Konica AGFA MR Detail

In manual mode default kVs can be programmed from 20 to 35 kV.

Pressing AUTOREL sends all the data for all exposures after last RESET toserial port (RS-232). The port can be connected to a printer. PressingAUTOEXP enters the AEC stations, which can be programmed with the keyfunctions as described below. (In software versions 5.06 and below)

KEY FUNCTION DISPLAY

kV+ Increase preset kV kV

kV- Decrease preset kV kV

mAs+ Set film/ screen combination/

mAs in manual mode

mAs

mAs- Set film/ screen combination/

mAs in manual mode

mAs

DEN+ Increase internal density DEN

DEN- Decrease internal density DEN

DEN+ & - Return to main program all

AUTOREL Send last exposure data through RSport

READY-led

AUTOEXP Change from AEC channel a -> b -> c corresponding led


June 2000 3-4 31687

3.2.3 Service program menu

Service program menu contains special programs for system setups, calibrationand diagnostics. The menu can be entered from service mode by pressingDen+ & Den- buttons simultaneously for approximately one second.

In the kV display you will see the program number and in the mAs display theprogram name. You can scroll the available programs with kV+ and kV-buttons. To enter the desired program press the Autoexp button.

Return to the menu from the special programs with Autoexp button. To leavethe menu and enter the service mode press density+ and density- buttonssimultaneously. To resume the normal operation (nor-mode) press kV-anddensity- buttons simultaneously for 3 seconds.

List of special programs:

Program # Program name Description

51 Pr Density and default value programming

52 SUP Set up parameter programming

53 Par Performa, Alpha parameter programming

54* CAn* C-arm angle display calibration

56* Cfo* Compression force display calibration

56* Cth* Compression thickness display calibration

57 Ano Anode run test

58 CEC Check error counters

59 Cin Check inputs

60 FoC Focus measurement mode

61 bUC Bucky measurement mode

62 Inf Print Performa, Alpha information

63* iqc Integrated Quality Control Parameters

64* AEC AEC Adjustment Parameters

65* tAr AEC Target time Adjustment

* Performa, Alpha RT/IQ only


31687 3-5 June 2000

Setup parameters:

The unit setup parameters can be altered in two programs:

In the setup section (program #52 SUP):

A Compression auto-release timeL Label typeH Label texti i/o deviceF Default filter selection

In the unit parameter section (program #53 Par)

S Serial number of the unitC Country coder Tube Efficiency mo/rh (mR/mAs)b Anode braking modet Mode (Performa/III/ST/RT/IQ)I Collimator selectd C-arm Control board select

The calibration programs:

The various measurements and displays can be calibrated in calibrationprograms:

#54 C.An C-arm angulation display calibration#55 C.fo Compression force display calibration#56 C.th Compression thickness display calibration#57 A.no Anode rotation program

The diagnostic programs:

The following programs are for system diagnostics:

#58 CEC Check error counters#59 Cin Check CPU inputs#60 FoC Focus measurement mode#61 bUC Bucky measurement mode#62 Inf System setup print out


June 2000 3-6 31687

The Integrated Quality Control program (Software version 7.27 and up):

#63 iqc Integrated Quality Control Program

The AEC Adjustment and parameters programs (Software version 7.27and up):

#64 AEC AEC parameters#65 tAr AEC Target Time Adjustment Program


31687 3-7 June 2000

3.2.3.1 SETUP-mode (SUP and Par programs; see 3.1)

Factory installation data (can also be set in the field) has 12 alterable items.Items to be set up are:

parameterDENSITY-display

range defaultvalue

description

Par 1 S 0-9999 Serial number of the unit

Par 2 C 9-16 10 Country code

Par 3 r 0-25.5 - mR/mAs output @25kV

Separate for Mo/Rh

Par 4 b 0-1 0 Anode brake mode (1=on/0=off)

Par 5 t 1-5 4 Mode, (1=AlphaIII, 2=Performa/RT/IQ,(Full-Man), 3=Performa/RT/IQ(Semi-Man), 4=Performa/RT/IQ(Full-Semi-Man),5=Performa/RT/IQ(Semi-Full-Man)).

Par 6 I 0-1 1 Collimator select (1= interlock, 0= non-interlock)

Par 7 d 0-1 0 0=C-arm control board (32310), 1=CD-board (32010)

SUP 1 A 0-25 6 Auto release time, (seconds)

SUP 2 L 0-5 0 Label type (0= print off)

SUP 3 H 0-60/255 32 Label programming mode

60 ascii chars

SUP 4 I 0-2 0 Serial port mode, (0=no I/O device,1=printer(1200bd),2=PC(9600bd))

SUP 5 F 0-3(Performa/

RT/IQ)

0-1 (ST)

1 Default beam filter programming,(0=Rhodium, 1=Molybden, 2=previouslyused, 3= "autofilter": use mAs+/- keys toselect the compression distance where filteris automatically changed

NOTE! Reset the CPU after changing the parameters.

NOTE! Items are updated to EEPROM when kV+, kV- or AUTOEXP-button ispressed.

Changing the parameters:

Enter the special program menu as described previously and select program#52 SUP or #53 Par with kV+ and kV- buttons. Press Autoexp button to enterthe desired program.


June 2000 3-8 31687

KEY FUNCTION DISPLAY AFF.

kV+ &kV- Scrolls the parameters to be set DEN

DEN+ Increase parameter value kV& mAs

mAs+ ONLY IN "h" Next characterposition

kV & mAs

DEN- Decrease parameter value kV& mAs

mAs- ONLY IN "h" Previouscharacter position

kV & mAs

Autoexp Switch back to program menu

Press Autoexp to leave the program and return to the special program menu.

To store the new values press Density + and Density - simultaneously untilservice mode is entered. Press kV- and Density- until normal mode is entered.Cut the power from the mains switch for few seconds.

3.2.3.2 Calibrations (see section 7 software block diagram)

C-arm angle display calibration

The c-arm angle display can be calibrated with special program #54 CAn.

Enter the special program menu as described previously and select program#54 CAn with kV+ and kV- buttons. Press Autoexp button to enter thisprogram.

The timer display will show CAn and kV and mAs displays will show to 00.Make sure that the c-arm is in 0 degree angle. Press Autorel; the 0 degreeangle is now programmed. The control unit shows to 180. Turn the c-arm to180 degree angle. If you want to use another angle for calibration you canchange the display with density +/- buttons. (You can abort the programmingand return to the program menu with Autoexp button).

Press Autorel. If the calibration was successful the mAs display will showPAS and you are returned to the program menu. If the calibration did notsucceed you will be returned to the beginning and "to 00" will displayed again.

Compression force display calibration

The compression force display can be calibrated with special program #55 Cfo.

NOTE! Make sure the C-arm angle display is calibrated before calibrating thecompression force display (Pr #54 Can). Also the offset voltage on C-armcontrol board must be 500mV when there is no stress on compressionpaddle.


31687 3-9 June 2000

Enter the special program menu as described previously and select program#55 Cfo with kV+ and kV- buttons. Press Autoexp button to enter thisprogram.

The timer display will show Cfo and kV and mAs displays will show to 50.Make a compression of 50 N. Press Autorel; the 50 N level is nowprogrammed. The control unit shows to 200. Make a compression of 200 N. Ifyou have a different level of compression you can change the display withdensity +/- buttons. (You can abort the programming and return to theprogram menu with Autoexp button).

Press Autorel. If the calibration was successful the mAs display will showPAS and you are returned to the program menu. If the calibration did notsucceed you will be returned to the beginning and to 50 will displayed again.

Compression thickness display calibration

The compression thickness display can be calibrated with special program #56Cth. Enter the special program menu as described previously and selectprogram #56 Cth with kV+ and kV- buttons. Press Autoexp button to enterthis program.

The timer display will show Cth and kV and mAs displays will show to 00.Drive the compression paddle completely down against the bucky. PressAutorel; the 0.0 cm level is now programmed. The control unit shows to 60.Place 60 mm acrylic on the bucky and drive the compression paddle down. Ifyou have 50 mm acrylic you can change the display with density +/- buttons.(You can abort the programming and return to the program menu withAutoexp button).

Press Autorel. If the calibration was successful the mAs display will showPAS and you are returned to the program menu. If the calibration did notsucceed you will be returned to the beginning and to 00 will displayed again.

Anode run voltage calibration

The anode run voltage can be adjusted with special program #57 Ano.

Enter the special program menu as described previously and select program#57 Ano with kV+ and kV- buttons. Press Autoexp button to enter thisprogram.You can now run the anode motor by pressing the exposure button.The Autorel button can be used to set the anode brake on/off.


June 2000 3-10 31687

3.2.3.3 Diagnostics (see 3.1)

The programs #58 -#62 are for system diagnosis.

In Pr #58 CEC the following counters can be checked:# exposures, E01, E02, E03, E04, E06, E07,E08, E09, E10, E11, E12, S.Lo,Er1, Er2, Er3, Er4, Er5, EAF, SYS and Err (last error).


AUTOEXP Enter or quit error countprogram

kV+/- Scroll countersmAs+ Reset the displayed counter kV and mAs

In #59 Cin program all the input-ports can be examined in the input-portscheck routine and the following internal counters for errors can be examinedand RESET in the error- exposure counter routine:


AUTOEXP Enter input-ports check routine Lo -> Hi = line ok

AUTOEXP Return to program menu

DEN+ & - Returns to SEr-mode timer shows"SEr

For information on #60 FoC focus measurement program refer to section 4.1.3Focal spot measurement procedure.

#62 INF program prints all preprogrammed default values and allprogrammable tables. THIS DOCUMENT SHOULD BE FILED AND USEDAS A BASE ADJUSTMENT DOCUMENT.

3.2.3.4 Integrated Quality Control History

In the program #63 iqc, 20 latest IQC correction coefficients can be seen.Scroll with kV+ or kV- . The kV display shows the reference number and themAs display shows the coefficient. IQC-coefficient is calculated from aformula:

New IQC-coefficient = Old IQC-coefficient * (Wanted opticaldensity/measured optical density)

Wanted optical density is defined in the program #64 AEC parameter d. InIQC mode the filter change is not allowed. Filter selection is made in theprogram #52 SUP parameter F (If F=2 then iqc used filter is molybdenum).

The allowed change of the coefficient is 40%, except Germany where 25%.If the change is bigger a C.PS error code is seen.


31687 3-11 June 2000

3.2.3.5 AEC adjustment parameters

Functional description of AEC full automatic mode

The initial kV is automatically selected based on the compressed breastthickness. In the beginning of the exposure the first estimation of the exposuretime at initial kV is made by measuring the radiation coming through thebreast. Based on this, the kV is automatically changed up or down, ifnecessary, to meet the target time. If the kV is changed, a second estimationof the exposure time at this kV is made by measuring the radiation and the kVis automatically changed again, if necessary, to meet the target time. Afterthe exposure the final kV is displayed.

The Auto kV performance can be optimized and configured according to theuser preferences. The configurable items are the initial kV (initial kV versusbreast thickness table), amount of allowable kV change (Max kV change inPr-mode, enter from normal mode with Den+/Den- 3sec.) and desired exposuretime range (target time). In program #64 AEC, parameter I determines themin/max values for target time. The target time is setup in program # 65 tArby giving two thicknesses and the respective desired exposure times. Thetarget times for other thicknesses are calculated with linear estimation. Thesystem selects the kV so that the desired target time can be reached. Themaximum allowable kV-change is more limiting, however, and thus a differentexposure time than the target time may result.

Thickness compensation adjustment

Software versions 7.27 and greater utilize a thickness compensation methodwhich compensates for variations in optical density (O.D) of the film.The rotation point can be programmed. The amount of rotation andcompensation curve slopes below and above the rotation point can beprogrammed separately.

Rotation point P

Rotation point is the exposure time where the O.D is adjusted correctly.Thickness compensation is achieved by altering the exposure time around thispoint. Default value is 1.00.

Amount of rotation r1 and r2

Parameters r1 and r2 determine the amount of compensation with exposuretimes shorter or longer than the rotation point respectively. r1 determines theamount of compensation at the point where exposure time is half the rotationpoint. r2 determines the amount of compensation at exposure time twice therotation point.

The values of r1 and r2 can vary from 0.70 to 1.30. If the parameter is 1.30 itmeans that exposure times are increased by 30%. If the parameter is 0.80 itmeans that the exposure times are decreased by 20% etc. Default values are 1.0for both.


June 2000 3-12 31687

Compensation curve slope parameters S1 and S2

Parameters S1 and S2 determine the curve slope for exposure times shorter orlonger than the rotation point respectively. S1 determines the slope at the pointwhere exposure time is lower than the rotation point. S2 determines theamount of compensation at exposure time higher than the rotation point. Referto the curves below for effects of the S parameters. The rotation point is 1.0seconds and the amount of rotation (r1 and r2) is 0.8, 0.9, 1.1 or 1.2 (= 80%,90%, 110%, 120%). Default values are 200 for both.

Compensation curve slope parameters S1 and S2

Parameters S1 and S2 determine the curve slope for exposure times shorter orlonger than the rotation point respectively. S1 determines the slope at thepoint where exposure time is lower than the rotation point. S2 determines theamount of compensation at exposure time higher than the rotation point. Referto the curves below for effects of the S parameters. The rotation point is 1.0seconds and the amount of rotation (r1 and r2) is 0.8, 0.9, 1.1 or 1.2 (= 80%,90%, 110%, 120%). Default values are 200 for both.

Figure 3.1 Effect of parameter S2

Figure 3.2 Effect of parameter S1

Exposure time / sec. Exposure time / sec.

r2 = 1.1

r2 = 0.9

r2 = 1.2

r2 = 0.8

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1 1.5 2 2.5 3 3.5 4 4.5 50.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1 1.5 2 2.5 3 3.5 4 4.5 5

S = 0S = 50S = 100S = 200S = 350S = 500S = 600S = 700

S = 0S = 50S = 100S = 200S = 350S = 500S = 600S = 700

S = 0

S = 700

S = 0

S = 700

P = 1.0sec P = 1.0sec

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

0 0.2 0.4 0.6 0.8 10.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

0 0.2 0.4 0.6 0.8 1

Exposure time / sec. Exposure time / sec.

r1 = 1.1

r1 = 0.9

r1 = 1.2

r1 = 0.8

S = 0

S = 700

S = 0

S = 700

S = 0S = 700

S = 0S = 700

P = 1.0secP = 1.0sec


31687 3-13 June 2000

In programs #64 AEC and #65 tAr the AEC is adjusted.

KEY FUNCTION

kV+&- Scroll parameters

DEN+ & - To change the value of the parameter

Parameters to be set in program #64 AEC are:

parameter range default value descriptiond 0.1-2.55 1.3 Wanted optical density (iqc) (only in

Performa/RT/IQ)h 0 /23-35 27 IQC-kV programming (only in

Performa/RT/IQ) 0=sensitometry basediqc, 23-35=phantom based iqc.

I Smallfocus:0.30-10.00Largefocus:0.30-5.00

MIN/MAX (SF):0.50/5.00MIN/MAX (LF):0.50/3.50

Target time MIN/MAX values in fullautomatic exposure (only inPerforma/RT/IQ).NOTE: Separate target times fordifferent Cassette holder/filtercombinations.

c - - Thickness compensation parameters.Press autorel to scroll P,r1,r2,S1,S2.

P 0.30-2.55 1.0 Rotation point of compensation curve(Exposure time in seconds where wantedoptical density was achieved).

r1 0.30-1.30 1.0 Compensation factor for exposure timesshorter than P.

r2 0.30-1.30 1.0 Compensation factor for exposure timeslonger than P.

S1 0-700 200 Compensation parameter for very shortexp times (fine tuning).

S20-700 200 Compensation parameter for very long

exp times (fine tuning).g 0.20-2.00 around 1 Software gain for optical density

adjustment. Replaces the hardware gaintrimmer.

E 23-35 See table 2.5 ininstallationmanual

Automatic kV default tablesprogramming (Only in Performa/RT/IQ)

Parameters in program #65 tAr to be set are:

1. Target exposure time for 1.5 cm thick breast (factory default = 0.50 sec.).2. Target exposure time for 9.5 cm thick breast (factory default = 2.40 sec.).

The software calculates the other thicknesses from these values.


June 2000 3-14 31687

To adjust target times:

1. Go into program #65 tAr (press autoexp) You will see in densitydisplay 0, in kV display the compressed thickness and in mAs displaythe target time for the compressed thickness. You can check the targettimes for different thicknesses now by driving the paddle.

2. Drive the paddle to 1.5 cm.3. Press Autorel4. Change the value with Den +/- buttons (Default 0.50 sec.).5. Press Autorel to accept6. Drive paddle to 9.5 cm7. Change the value with Den +/- buttons (Default 2.40 sec.).8. Press Autorel to accept. You will see PAS or ERR depending on the

new values if they were acceptable or not.

When to adjust target times:

AEC adjustment quick fix guide

Problem Probable Reason Action Comments

No contrast withlarge breasts

Full AEC kVs with largebreasts too high.

Increase the Target time withlarge breast thickness. (Pr# 65tAr program)

Results in lowerkV with largebreasts

No contrast withsmall breasts

full AEC kVs with smallbreasts too high.

Increase the Target time withsmall breast thickness. (Pr# 65tAr program)

Results in lowerkV with smallbreasts.

mAs too high, longexposure times

Full AEC kVs low Decrease the Target time values Low kVs yieldlong mAs

O.fl errors or

"white images"

Start kV too low and/ormaximum allowable kVchange too small.

Change the full AEC kV table(Pr# 64 AEC parameter E) orIncrease the kV change value (Prmode)

EAf errors Poor connection betweenCPU and AEC boards.

Incorrectly adjusted AECoffset voltages

Check the cabling.

Adjust the AEC board offsetvoltages.

EAf error at start up AEC board supply voltagesproblems

or autozeroing circuit doesnot work at start up.

Check the AEC board supplyvoltages.

If you are using the 32315 AECboard with software 7.27 or later,you can remove the capacitorC35 (22F)

"white images" O.fl, U.fl or C.cn error code Check the bucky connection(apply compression)


31687 3-15 June 2000

3.3 USING THE SERIAL PORT IN FOR COMMUNICATION

3.3.1 The Cable

For the cable, there are two options because there are two ways to connect aserial port of a PC. Some older models of personal computers use a 25-pinD-connector for serial communications while normally 9-pin connector isused. The cable for both options is illustrated below:

Choose either the 9-pin or pin 25-pin version.

To see that the communication works properly, you might want to add a pair ofLED's between GND and both data lines. This can be done with two 1000 ohmresistors connected in series with the LEDs. The direction of leds is notimportant because both (input and output) channels have voltage levels from-12 to +12 volt.

Alpha/Performa

Alpha/Performa


June 2000 3-16 31687

3.3.2 Communication protocol

The serial connection is an ordinary asynchronous receiver/transmitter.

The serial port is initialized in Performa, ALPHA III/ST/RT/IQ as follows:

1200 baud (9600 baud with 5.09 software and if Dataview is connected)8 data bitsno parity (always 0)1 stop bit

The effect of the 'no parity bit' and the stop bit is a total of two stop bits, soreceiving end must be configured correspondingly. The data byte looks thefollowing:

START 8-BIT DATA 2 STOP

The data can be received with a communications program (for exampleProcomm) to PC and be printed afterwards on paper. This might be moreconvenient than a printer with RS 2 because it is not a standard equipment.

3.3.3 Data formats

Performa, ALPHA III/ST/RT/IQ can send two different groups of data:

1) Diagnostic information about the system, like serial number, exposureparameters and number of error situations. This information can be sentto serial channel by pressing AEXP in the diA/inf-mode. This is meantto be sent to either PC or printer. An example of this data is displayedon the next page:


31687 3-17 June 2000

INSTRUMENTARIUM Imaging, MGF 101/110 information, SW v.7.30, 01-Jan-2000========================================================================DEVICE#: 08224 ALPHA MODE: RT(4)COUNTRY CODE: 010 ANODE BRAKING IS OFFCARM BOARD: MCURADIATION EFFECIENCY 10.2(Mo), 08.1(Rh) mR/mAs at 25 kVAUTOREL TIME(s): 006 SW gain for AEC-board: 1.00LABEL TYPE: 000 I/O DEVICE: PRINTERLABEL TEXT IS:

IQC multiplier: 1.00 IQC MODE: NO EXPOSUREWANTED DENSITY: 1.30DEFAULT FILTER: MolybdeniumEXPOSURE COUNTER: 0001276ERROR CNT: E01 E02 E03 E04 E07 E08 E09 E10 00000 00000 00003 00000 00000 00000 00010 00005 E11 E12 SLO ER1 ER2 ER3 ER4 ER5 EAF SYS00016 00013 00000 00000 00001 00000 00000 00000 00050 00000PROGRAMMED VALUES: Full BUCKY(Mo) MAGN(Mo) CONTACT(Mo) kV f/s den kV f/s den kV f/s den A= 00004 00001 00007 00004 00001 00007 00000 00004 00007 B= 00004 00001 00007 00004 00001 00007 00004 00001 00007 C= 00004 00001 00007 00004 00001 00007 00004 00001 00007 BUCKY(Rh) MAGN(Rh) CONTACT(Rh) kV f/s den kV f/s den kV f/s den A= 00004 00001 00007 00004 00001 00007 00004 00001 00007 B= 00004 00001 00007 00004 00001 00007 00004 00001 00007 C= 00004 00001 00007 00004 00001 00007 00004 00001 00007PROGRAMMED VALUES: Semi BUCKY(Mo) MAGN(Mo) CONTACT(Mo) kV f/s den kV f/s den kV f/s den A= 00027 00001 00007 00027 00001 00007 00027 00001 00007 B= 00027 00001 00007 00027 00001 00007 00027 00001 00007 C= 00027 00001 00007 00027 00001 00007 00027 00001 00007 BUCKY(Rh) MAGN(Rh) CONTACT(Rh) kV f/s den kV f/s den kV f/s den A= 00027 00001 00007 00027 00001 00007 00027 00001 00007 B= 00027 00001 00007 00027 00001 00007 00027 00001 00007 C= 00027 00001 00007 00027 00001 00007 00027 00001 00007PROGRAMMED VALUES: Man BUCKY(Mo) MAGN(Mo) CONTACT(Mo) kV mAs kV mAs kV mAs 00027 00012 00027 00012 00028 00012 BUCKY(Rh) MAGN(Rh) CONTACT(Rh) kV mAs kV mAs kV mAs 00027 00012 00027 00012 00027 00012PRINTED VALUES OF DENSITY: 0..14 = -7..+7FULL-AEC TARGET TIME variables + limits: BUCKY: Mo: 0.25 +0.10 0.50 3.50 BUCKY: Rh: 0.25 +0.10 0.50 3.50 MAGN: Mo: 0.25 +0.30 0.50 5.00 MAGN: Rh: 0.25 +0.30 0.50 5.00 CONTACT:Mo: 0.20 +0.20 0.50 3.70 CONTACT:Rh: 0.15 +0.20 0.40 3.50THICKNESS COMPENSATION variables: BUCKY: Mo: 1.00 1.00 1.00 250 250 BUCKY: Rh: 1.00 1.00 1.00 250 250 MAGN: Mo: 1.00 1.00 1.00 250 250 MAGN: Rh: 1.00 1.00 1.00 250 250 CONTACT:Mo: 1.00 1.00 1.00 250 250 CONTACT:Rh: 1.00 1.00 1.00 250 250FULL-AEC kV-TABLES:mm: 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95BUCKY:Mo: 23 23 23 23 23 23 23 23 24 24 25 26 26 27 28 29 30 31 32 33Rh: 23 23 23 23 23 23 23 23 24 24 25 26 26 27 28 29 30 31 32 33MAGN:Mo: 25 25 25 25 25 25 25 25 26 26 26 27 27 28 28 28 29 29 30 30Rh: 25 25 25 25 25 25 25 25 26 26 26 27 27 28 28 28 29 29 30 30CONTACT:Mo: 23 23 23 23 23 23 23 23 23 23 24 24 24 25 25 25 26 26 27 28Rh: 23 23 23 23 23 23 23 23 23 23 24 24 24 25 25 25 26 26 27 28EPROM CHECKSUM: Calc = 52255 Set = 52255


June 2000 3-18 31687

2) After each exposure the exposure data is sent to serial port if the L-parameter (in SETUP) is > 0. If the L-parameter (in SETUP) is 1 thedata is printed on one line, for example:

02693,01429,335,027,00234,7,7,1,100,080,150,001,Rh,00123, OK ,B,FULL

02693 Exposure counter01429 integration time335 exposure time027 kV00234 true mAs7 programmed density7 density1 film/screen100 IQC -multiplier080 compression thickness150 compression force001 angle of C-ArmRh Filter00123 doseOK error codeB technique ( M / N )FULL exposure mode (SEMI / MAN / IQC)

If the L-parameter (in SETUP) is > 1 the printout is:

B Rh 0.02s 28kV 002mAs +0 HOSPITALxNAMEx6.5cm 200N 180^/R 0.06mGy CODExxxxxxxxxx___/___/___ R1 12345 RADIOLOGISTxxx_________________________ DEPARTMENTxxxx

Explanations:B Bucky / Cassette tunnel / MagnificationRh Rhodium / Molybdenum filter+0 Density correction28kV kV002mAs mAs0.02s Exposure time6.5cm Breast thickness200N Compression force180^/R C-arm tilt angle, ^= degrees (), to the /Right or /Left0.06mGy Average patient dose___/___/___ Date is handwritten after printing the labelR1 Site of the detector (L1, L2, C1, C2, C3, C4, R1, R2)12345 Exposure counter, up till 99999_____________________ Patient name is handwritten after printing the label


31687 3-19 June 2000

If the L-parameter is 2 the consecutive labels are printed 5 rows apartIf the L-parameter is 3 the consecutive labels are printed 3 rows apartL=4 and L=5 include exposure information and are used for testing purposesonly.

3.4 THEORY OF OPERATIONS

3.4.1 Process controller

3.4.1.1 The CPU BOARD

The CPU board is the heart of Performa, ALPHA III/ST/RT/IQ. It controlsevery function in the unit, except the ROTATIONAL BRAKE. The 8031microprocessor on the CPU board controls kV GENERATION ,mAGENERATION (via the FILAMENT CONTROL board) and the rest of thefunctions through latches and buffers directly and uses a keyboard controller(8279) to handle the control panel..

The I/O-control (latches and buffers) controls the vertical drive motor,compression motor, bucky, anode motor, foot switches, microswitch reading,and the AEC. The 8279 reads and decodes the control panel switches, as wellas drives the control panel display.

Exposure times in both manual and AEC mode are calculated and controlledby software and the microprocessor.


June 2000 3-20 31687

COMPRESSION


31687 3-21 June 2000

3.4.2 User interface

3.4.2.1 Switch and microswitch reading

The control panel switches on the PERFORMA, ALPHA III/ST/RT/IQ areconfigured in a row/column matrix (fig. 3.1) that is strobed and read by theCPU board. D15 on the CPU board is an 8279, which is a keyboard controller.It will strobe each column looking for a return on one of the rows, which it willonly find when a switch is pressed. For example, if the circled switch is closed,the resulting timing chart will be as given in fig. 3.2.

This will let the CPU know that the switch S2/R0 is pressed. The softwaredefines that the switch is the kV-button and decreases the kVref on the PULSEboard.

The hand switch (exposure button) signal is fed through the CPU board to thepulse board where it becomes an enable for the exposure circuitry before it isfed back to the CPU board as signal EXP2 on connector X5 pin 9. This allowsthe operator to stop the exposure in the event of a CPU board malfunction.

3.4.2.2 Collimator lamp operation

When the COMPRESSION DOWN switch is activated, in addition to the CPUturning on the compression motor, it also sends a signal called PROJ RELAY,and starts a software timer. The PROJ RELAY signal is fed to the SUPPLYboard where it activates relay K1 turning on the collimator lamp. The lamp isshut off when the timer runs out ( about 8 sec.) or the hand switch is pressedand the exposure sequence is started.

S0 S1 S2 S7

R0

R1

R2

R7

S0

S1

S2

S3

S4

S5

S6

S7

R0

R1

R2

R3


June 2000 3-22 31687

3.4.2.3 Cassette sensing CASOPTO BOARD

Cassette sensing is accomplished by using two (one in optipoint) opticalsensors (fig. 3.3). Each sensor has two halves, an infrared source and aninfrared detector.

Figure 3.3. Cassette sensing

The cassette bottom forms the reflective surface needed. There is a green LEDwhich comes on to indicate that the cassette is being sensed and the CASNOR-signal is sent to the CPU.

3.4.2.4 Cassette holder sensing CSENSE BOARD

The cassette holder sensor has four reed relays in it, three of them (CHL,CHRand K4) are used to decode cassette holders for the CPU. The fourth read relay(CHON) ensures the cassette holder is completely attached. The identificationis done with magnets attached to the holders.

CHL CHR For small cass. holder and smallCas holder 1 1 bucky the K4 is also activatedBucky 0 1Mag box 1 0Stereotact 0 0

0 = Not activated1 = Activated

CSense Board:


31687 3-23 June 2000

3.4.3 X-RAY GENERATION AND CONTROL

X-ray generator block diagram

The generator of the unit is a modern, constant power, high frequency,feedback-controlled DC x-ray generator consisting of the following parts:

1. Inverter board2. Filament Control board3. High voltage unit4. Anode motor drive (AMD) board5. Mains transformer6. Energy storage capacitor7. Tube housing

Technical specifications are:

Input power: 3500 W ( 6500 VA) maxOutput power: 2500 W maxOutput voltage : 20 - 35 kVOutput current : 10 - 100 mAFrequency: 20 - 90 kHzLine voltage: 220/ 240 10% 50/60HzIRMS(rest): 1 AIRMS(exposure): 30 AIpeak: 55 A


June 2000 3-24 31687

3.4.3.1 INVERTER BOARD

The INVERTER Board controls the high voltage (kV) generation. The kVlevel is digitally set by the CPU board.

The Inverter Board contains a high voltage and a low voltage section. The highvoltage section is isolated from the low voltage section with pulse transformersTF1, TF2 and relays K1,K2.

WARNING! Voltages in the high voltage part of the INVERTER Board are deadly.The peak to peak voltage exceeds 700V in normal operation.

High voltage section:

The high voltage section consists of a MOSFET transistor H-bridge whichconverts the rectified line voltage (+310 VDC) into high frequency current.This current is taken to the HIGH VOLTAGE UNIT where it is transformedinto high voltage. The inductors L1, L2 and capacitor C8 act as parts ofresonant circuit which shapes the bridge current. The RMS value of thecurrent is controlled by the H-bridge's operating frequency. The MOSFETdriving pulses are generated at the low voltage section of the board and areprovided by the pulse transformers TF1 and TF2.

TF3 is a current transformer which monitors the bridge current. If the bridgecurrent exceeds the pre-adjusted current limit the control circuit in the lowvoltage section turns the MOSFETs off.

Timing:

The line voltage is applied through the connector X1. When an exposure isinitiated, relays K1 and K2 provide the rest of the board with line voltage.Relays K1 and K2 are activated with signals RG1 and RG2 respectively. K1applies voltage to the bridge rectifier D3 through the current limiting resistorR1 which allows controlled charging of the energy storage capacitor(connected to X2). K2 is activated approximately 0.8 seconds later andprovides the circuit with full power. Finally, the activation of the EXPENAsignal (TP17) enables the H-bridge drive circuitry.

Low voltage section:

kV control:The high voltage is regulated by adjusting the H-bridge's operating frequency.This is done by comparing the feedback signal (HVFB) from the high voltageunit with the reference from the CPU BOARD and taking the error signal tothe frequency modulator circuit (ICA1, ICA4, ICD1, ICD2). The output istaken to ICA5 and ICA6 which drive the pulse transformers TF1 and TF2.


31687 3-25 June 2000

EXPENA signal:An exposure is initiated by the CPU BOARD by activation of the EXPENAsignal. This enables pulse transformer drivers (ICA5, ICA6) and allows thekV reference signal to rise providing "soft start".

TUBEFAIL signal:TUBEFAIL signal is activated if the kVFB signal does not reach the kVreference. This typically occurs during a high voltage breakdown. ASHUTDOWN for the kV control is provided. As the high voltage breakdownis characteristic to x-ray tubes, and hence may occur during normal operation,the exposure is continued with a new activation of the EXPENA signal. TheCPU Board allows three (3) tube failures per exposure before an errormessage (E02) is displayed.

Test Switch:Test switch S1 allows an exposure sequence to continue regardless of thekVFB signal. In "TEST" position the TUBEFAIL signal is forced down .

Note! The Test Switch S1 should always be at "NORMAL" position wheneverthe high voltage part of the INVERTER BOARD is energized. Failing todo this may damage the INVERTER BOARD, HIGH VOLTAGE UNITand the X-RAY TUBE.

An exposure without X-rays:It is possible to check the operation of kV control circuitry without X-rays.

1. Unplug the connector X12. Set the test switch S1 to "TEST" position3 Unplug the connector X4 on the FILAMENT CONTROL Board4. Set the test switch on FILAMENT CONTROL Board to "TEST"

position 5. Set the jumper X8 ("FBSEL") on the FILAMENT CONTROL

Board to position 1-2 (left hand position)6. Initiate the exposure

The control circuitry is driving the MOSFETS with the minimum frequency(app. 20kHz).

Back Up Timer:The Back Up Timer is located on the FILAMENT CONTROL BOARD and itdisables both the +34REL voltage and the EXPENA signal providing aSHUTDOWN approximately fifteen (15) seconds after the activation of theEXPENA signal. This is a safety feature only and does not affect normaloperation.


June 2000 3-26 31687

kV reference:The level of the used kV is set by the CPU BOARD with signals DATA0 -DATA7. This 8 bit digital word contains the kV reference . The kV referenceis converted into an analog signal in D/A converter ICA2 (TP24).

The analog kV reference (TP24) and the kV feedback (TP22) signalscorrespond to actual kV as follows: kV = DVM read-out * 10 kV

For example, if the digital multimeter (DVM) read-out is 2.5 V the actual highvoltage is 25kV.

kV adjustment:The calibration of the kV is done by adjusting the D/A converter's (ICA2)reference voltage with trimmer potentiometer R63.

Note! The kV calibration is performed at the factory. The trimmerpotentiometer R63 is sealed . Manipulation of the potentiometer can becarried out by authorized personnel only. Improper settings of thepotentiometer can damage the INVERTER BOARD, HIGH VOLTAGEUNIT and the X-RAY TUBE

External indicators:Connector X6 provides relay contacts for X-ray system status indication. X6pins 1 and 2 are short circuited when the unit is on. X6 pins 3 and 4 are shortcircuited when X-rays are being generated. The contacts are rated for 5A,24VDC /240VAC.

Fuses:High Voltage fuse in the INVERTER BOARD (F1) is to protect the board incase of a short circuit.

-F1 20 AF /500V High voltage!

List of LED indicators

LED indicator SignalH1 +310VDCH2 EXPENA signalH3 Bridge CurrentH4-H5 Pulse A (MOSFET drive pulses)H6-H7 Pulse B (MOSFET drive pulses)H8 +15VH9 +34VH10 -15VH11 +25VH12 +34VREL


31687 3-27 June 2000

List of Test PointsTest Point SignalTP1 +310V GND High voltage!TP2 +310 VDC High voltage!TP3 High voltage!TP4 High Voltage!TP5-TP7 MOSFET gate High Voltage!TP8-TP10 MOSFET gate High voltage!TP11-TP13 MOSFET gate High voltage!TP14-TP16 MOSFET gate High Voltage!TP17 EXPENA signalTP18 SHUTDOWN signalTP19 GNDTP20 Operating frequencyTP21 Pulse ATP22 kV FeedbackTP23 Pulse BTP24 kV ReferenceTP25 GNDTP26 +34VTP27 +15VTP28 GNDTP29 GNDTP30 -15VTP31 -34VTP32 +34VRELTP33 +25V

Schematics, Layouts

Refer to the documents in section 7.

3.4.3.2 The high voltage unit

In the secondary of the high voltage transformer, there is a voltage doubler. Asone half of the inverter is conducting, secondary current flows through one setof diodes, charging one of the 1.2 nF capacitors in the tank. When the otherhalf is conducting, the current flows through the other set of diodes andcharges the other 1.2 nF capacitor. Since the capacitors are connected in series,the voltage across the capacitors is double the voltage of secondary. There is a450 Mohm resistor connected to the high voltage output forming the upper legof the voltage division. On the Inverter board is the lower leg over which thecontrol circuit measures the voltage. The modulator compares this voltage tothat of a reference and changes the output frequency, if necessary, to maintainthe proper kV.

The output of the hV-unit is directly connected to the anode of the tube with ahigh voltage cable. The unit also contains a rubber bottle because of theexpansion of oil volume due to rising temperature.


June 2000 3-28 31687

3.4.3.3 mA generation timing

mA generation timing is controlled with four signals: FOCUS, PREHEAT,PREH and EXT. FOCUS is a latch output which changes state depending onwhether the mag-box (small focal spot) or either the bucky or cassette tunnel(large focal spot) is attached to the machine. It selects which mA feedbackresistor is used on the FILAMENT CONTROL board and which filament isenergized. PREHEAT becomes active 55 milliseconds after the hand switch isdepressed. It powers relay K2 on the FILAMENT CONTROL board andsupplies power to the filament transformer TR1. During the time betweenPREHEAT and EXT, the pulse width modulator (ICA8) uses filament voltageas its feedback voltage. The feedback voltage is gain is controlled withtrimmer potentiometers R28 and R96 to achieve proper tube current rise at thebeginning of an exposure. (See PREHEAT ADJUSTMENT in the Adjustments& Alignments Section).

When EXT goes active, actual exposure begins. We are now no longerinterested in filament voltage; now, we must regulate tube current. Toaccomplish this, the common of the filaments is connected to ground throughone of the feedback resistors (R77 or R78) on the FILAMENT board. Thissignal called mA FEEDBACK (MAFB) is now fed to the pulse widthmodulator by the analog switch (ICA10). Its output was switched fromfilament voltage to MAFB with the signal PREH. The PREH signal isactivated approximately 7 ms after the EXT signal. The duty cycle of thepulse width will vary depending on what is required to maintain proper mA.

3.4.3.4 FILAMENT CONTROL BOARD

The CPU board begins the mA generation cycle when it sees the EXP2 signalfrom the FILAMENT CONTROL Board. The EXP2 is activated from theexposure button. The control of the mA and kV are handled through the serialto parallel converter / latch (ICD3). The latch is configured to have four majorfunctions:

1. Control/Timing2. Serial output back to the CPU board3. kV reference4. mA reference

kV referenceThe kV reference is converted into eight (8) parallel DATA bits which containthe kV reference information for the INVERTER BOARD. The kV referenceoccupies ICD3 pins 23 through 30.

mA referenceThe mA reference is converted into eight (8) parallel DATA bits which containthe mA reference information. The mA reference occupies ICD3 pins 11through 18.


31687 3-29 June 2000

mA control:The mA control adjusts the X-ray tube's filament heating level to provide thedesired tube current (mA). This is done by regulating the filament voltagewith "FLYBACK" type pulse width modulated switch mode power supply (T1,T2, TR1, D6, C12, ICA8). The control circuitry utilizes current mode controlwhich provides better stabilization and protects the semiconductor switchesagainst over current.

The operation consists of two consecutive sequences: the preheat sequence andnormal mA control sequence. The preheat sequence is used for heating of thefilament to the desired level prior to the exposure, in order to achieve optimummA rise at the start up. During the preheat sequence the control feedbackcomes from the filament voltage, and during an exposure the mAFB signal isused, providing the actual tube current monitoring.

Preheat adjustment:The Preheat adjustment is done separately for large and small focus withtrimmer potentiometers R28 and R96 respectively. (See PREHEATADJUSTMENT in the Adjustments & Alignments Section) The FOCUSsignal selects the corresponding trimmer with relay K3. During the preheatadjustment measure the tube current from TP4.

EXT signal:The EXT signal enables the kV generation.

FOCUS signal:The FOCUS signal changes the mA feedback circuit according to the selectedX-ray tube focal spot size. It also changes the filament that is being powered.When FOCUS signal is high (led H1) a small focus (0.1) is selected.

PREH signal:The PREH signal changes the filament control mode from preheat to normalexposure. The jumper X8 is used to disable the PREH signal during testing.

PREHREL signal:A preheat sequence is initiated before each exposure (before activation of theEXT signal) with the PREHREL signal. This activates the relay K2, providing+34V input voltage for the filament power supply and the INVERTERBOARD. The PREHREL signal enables the mA control circuit also.

mA feedback:Feedback voltage to the filament power supply controller ICA8 is selectedwith the analog switches ICA10. The source depends on the control signalEXT as follows:

STATUS EXT (TP8) FEEDBACK SOURCEpreheat sequence passive (0V) Filament voltagenormal exposure active (+15V) mA feedbackstand by passive (0V) Filament voltage


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Jumper X8:The jumper X8 is used for keeping the filament control in preheat mode duringthe whole exposure. This is intended for testing purposes only. The jumpershould normally short circuit pins 2 and 3 (right hand position) Note: Alwaysremember to leave the jumper in the right hand position after servicing theunit.

mACHK signalComparator ICA6 monitors the mA feedback signal and activates the mAOksignal when mA is present.

BuzzerBuzzer (BZ1) is activated with signal RG2. It indicates that X-rays are beinggenerated. (Note: The buzzer is activated during an exposure without X-raysalso; see section 3.4.3.1:Timing)

C-arm angle measurementThe c-arm angle measurement is done with a potentiometer in the c-arm brakeassembly. The potentiometer gives a voltage proportional to the angle. Thisvoltage is taken to the 12 bit, serial mode analog to digital converter ICA12.The control signals and data signal comes from the CPU board to connectorX12.

FB MISS signalThe FB MISS signal is activated if the feedback cable is not connected. This isto protect the high voltage transformer in case the feedback connector isaccidentally left open. Activation of this signal disables the EXP2 signal to theCPU board. This feature requires that the unit has cabling that short circuitspins 1 and 2 in X4. If the unit does not have that kind of cabling you can usethe board if you install a jumper connector X11 that grounds the pin 2.

Back Up Timer:The Back Up Timer disables both the K2 and the EXPENA signal for theINVERTER Board providing a SHUTDOWN approximately fifteen (15)seconds after the activation of the EXT signal. This is a safety feature only anddoes not affect normal operation.

Test Switch:The test switch S1 allows an exposure sequence to continue regardless of themAOK' signal which indicates that tube current is present.

X-ray tube biasThe filament is biased by having the tube current going trough a bias resistor (0, 220 or 300 ohms).The value of the resistor is determined at the factoryseparately for each tube and should therefore not be changed or modified.


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Supply voltages:The +15 V supply voltage is regulated from the +34 V with switchingregulator ICA11, and the -15 V is regulated from the -34V with linearregulator ICA9.

Fuses: Fuses F1 and F2 protect the board in case of short circuits

- F1 6,3 AT (=slow), 6,3 x 32 mm- F2 6,3 AT (=slow), 6,3 x 32 mm

List of LED LEDindicators indicator Signal

H1H2 Filament voltageH3 TubeFail signal (E02 error)H4 PrehRelH5 RG1H6 RG2H7 EXTH8 +15VH9 +34VH10 -15V

List of Test Points Test Point Signal

TP1 Filament VoltageTP2 MosFet gateTP3 Filament FeedbackTP4 mA FeedbackTP5 PrehRel TP6 RG1TP7 RG2TP8 EXT signal

TP9 +34VTP10 +15VTP11 -15VTP12 GNDTP13 GNDTP14 -34VTP15 mA Reference

Schematics, Layouts

Refer to the documents in section 7


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3.4.3.5 Anode motor drive AMD BOARD

The unit utilizes a rotating anode tube. The anode plate is accelerated with 230VAC before the emission of electrons from cathode. During exposure, statorneeds a certain running voltage (40-100 VAC), and after exposure the anodeplate can be braked.

All this is done with the phase control of a triac (V1). The control element isTelefunken TEA1007 (A7). Acceleration is achieved directly with mainsvoltage. During exposure, the firing angle of the triac is set to a level thatcorresponds the required RMS voltage. Braking is done by half wave rectifiedmains voltage. Acceleration and braking times are approx. 1 second. Safetyfeatures are also taken into account by monitoring the current of the triac.Should errors be detected, the microprocessor does not allow exposures. Theexchange of information between the microprocessor and this board isoptoisolated because the anode motor drive board is floating on mains voltage.

3.4.3.6 Mains transformer

The power and control side of the unit uses only one 50/60 Hz transformer. Itis a two slot 120 VA EI transformer. The first slot contains primary 220 V andsecondary 15 V for the protection circuit of the power transistors ( this is donebecause the protection circuit is floating on mains voltage ), the second slotcontains the actual secondary 2 x 24 V for AUX POWER. A grounded staticshield is situated between these slots.

3.4.3.7 Energy storage capacitor

The energy storage capacitor is used for smoothing the rectified mains voltagefed to the POWER board. It is an aluminum electrolytic capacitor 2200 uF /400 V with a 4K7 /11W bleeder resistor.

3.4.3.8 Motor phase shift capacitor

The motor phase shift capacitor is needed to rotate the anode plate. Itscapacitance is 40 uF / 450 V.

3.4.3.9 Tube housing assembly

Contains expansion systems and thermal switches and tube insert.

3.4.3.10 X-ray tube bias circuit (M101G)

The filament of the M101G X-ray tube is biased by having the tube currentgoing trough a bias resistor (0, 220 or 300 ohms).The value of the resistor isdetermined at the factory separately for each tube and should therefore not bechanged or modified.


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3.4.4 Motor control

3.4.4.1 Motor control - general

As you can see from the block diagram to the left, all interfacing between themicroprocessor and the motors is handled by 8255 peripheral controllers (D8and D16) on the CPU board. The one exception to this is BHOME signal,which goes directly to the 8031.

The microprocessor writes to and reads from the 8255 when its chip select (pin6) is active. Information is transferred back and forth on the data bus. Becauseof this, the outputs of the 8255 are the effective origin of the signals, and theinputs to it are effectively the final destination of all the signals.

3.4.4.2 C&Z DRIVER BOARD

This board controls the compression and vertical drive motors (also called C-and Z movements). It also provides regulated +24V dc-voltage to the bucky.

Both C- and Z- motors are +24V dc-motors which are driven with pulse widthmodulated (PWM) power supplies that can provide variable voltage controlthus enabling a rough speed control. Each drive circuit consists of controlcircuit and two power transistors. The output voltage consists of +34 Voltpulses whose width determines the RMS voltage of the motor. This voltage isproportional to the reference voltage applied to the control circuitry. Theoperating frequency for both drives is app. 30kHz.

Carriage motor (Z-motor)This is also called vertical drive motor. The vertical drive has two speeds.The movement is started with slow speed that allows accurate positioning ofthe carriage. After app. 2 seconds the faster speed is activated.

The CPU controls the vertical movement with two signals:

ZDIR signal:This signal sets the status of the relay K3. It determines the polarity of Z-motor voltage that is, the direction of the carriage.

ZRUN signal:This signal activates the PWM circuit (ICA5) which applies voltage to themotor. The RC circuit R60 and C21 determine the slow speed time interval.

Lower Limit, Upper LimitThese signals provide a way to limit the movement. When Lower/Upper Limitsignal is low only upwards/downwards direction is enabled. This is for futurepurposes.


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Compression motor (C-motor)The compression motor has three different speeds: fixed high speed up,trimmer potentiometer controlled high speed down and trimmer potentiometercontrolled low speed down. The purpose of these speeds is to provide "soft"compression. This is done by reducing the speed of the compression paddle assoon as the paddle reaches the breast.

The control of the compression is done by monitoring the compression motor'scurrent which gives us a rough idea of what the actual torque of the motor is.The current of the motor is measured with resistor R29 and then compared totwo predetermined threshold levels. The first threshold level, speed threshold,determines the force that the speed of the compression is reduced. Turn thetrimmer potentiometer R43 to set this level. The second threshold level,current limit, determines the final compression force. Turn the trimmerpotentiometer R33 to set the compression force.

The CPU controls the compression movement with following signals:

CDIR signal:This signal sets the status of the relay K1. It determines the polarity of the C-motor voltage that is, the direction of the compression paddle.

CRUN signal:This signal activates the PWM circuit (ICA4) which applies voltage to themotor. The reference voltage is selected from three different speed referenceswith analog switch ICD5. The choice depends on the direction of thecompression paddle and the speed threshold level.

SPEED signal: (for future purposes)This signal enables the CPU to reduce the compression speed regardless of thespeed threshold level.

CMAN signal:This signal activates the relay K2 which connects diode D10 across the motorterminals. The purpose of this diode is to prevent the motor from rotating whenthe breast is under compression.

+24Vin Bucky:Linear regulator ICA6 provides regulated +24V dc-voltage to bucky controlboard.


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Adjustment of the compression speeds:

1. Adjust the high speed compression to app. 2cm /1 seconds.2. Turn trimmer R43 until only low speed is on.3. Adjust the low speed compression down to app. 1cm /1 seconds4. Adjust the trimmer pot R43 so that the paddle switches to low speed

when it reaches the breast. Make sure the paddle travels in high speed(free air) at all angles. If not increase the speed threshold level.

5. Adjust the final compression force with trimmer R33. The compressionforce limit can be adjusted by software setting in service program(version 7.36 and up). In this case compression force with trimmer R33is adjusted to be 25-27 kg (53-59lbs) and force stop has been set bysoftware.

List of LED:s: LED SignalH1 +34VdcH2 +15VdcH3 +24Vdc for buckyH4 C-motor voltageH5 Z-motor voltageH6 Upper LimitH7 Lower Limit

List of testpoints: Test point SignalTP1 +34VdcTP2 +15VdcTP3 +24Vdc for buckyTP4 low speed referenceTP5 high speed referenceTP6 speed reference paddle upTP7 vertical drive speed referenceTP8, TP9 C-motor voltageTP10, TP11 Z-motor voltageTP12 GNDTP13 GND

Schematics and layouts: Refer to section 7.

3.4.4.3 Back up release

The units are equipped with a compression back up feature. If the line voltagesuddenly disappears the compression paddle is driven up. This is implementedwith a back up transformer in the back of the unit. The back up transformer isenergized whenever the unit is connected to the line supply. This back uptransformer provides power for the relay K4 on the Filament Control board.When this relay is powered the compression motor is driven normally. Whenthe relay is not activated the motor is driven upwards with the voltage in thecapacitors C20 -C31 on the Filament Control board. The status of the relay K4is indicated with a LED next to the main switch.


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3.4.4.4 Anode motor

After the hand switch has been depressed, the microprocessor will signal the8255 (D8) on the CPU board to output four signals that are ANSTART,ANENA, ANRUN and ANSTOP. ANRUN is the first signal to go active, it isnormally high to extend opto coupler life on the ANODE MOTOR DRIVER(AMD). It will go low in preparation for the ANENA signal so there is noarching when K1 relay on the AMD is pulled. After ANENA has enabled theanode motor, ANRUN goes high supplying the motor with 40 V. Seventymilliseconds later ANSTART goes low turning on the opto coupler A4, whichpulls pin 6 of the motor controller (A7) high. This turns the triac V1completely on supplying the rotor with 220 VAC. After nearly 1.5 seconds ofboosting, ANSTART goes high again ending the boost phase so the voltageapplied to the rotor drops back down to 40 V. After the exposure is finished,ANRUN goes low removing all power from the rotor so there will be noarching when ANSTOP pulls relay K2 to remove the phase shift capacitor andwinding from the circuitry for the braking.

An anode brake can be selected in the SETUP mode.The braking is done by applying a half wave rectified voltage to the mainstator winding. This produces a stationary magnetic field acting on the rotor.The phase shift winding does not get any voltage.

After the relay K2 has settled, ANRUN goes high again applying 40V halfwave rectified voltage to the stator. To begin braking shortly after thatANSTART goes low applying the full 220 V half wave rectified voltage to thestator.

STARTOK and RUNOK are two signals that the CPU monitors on during theboost and run phase respectively. They will go low if the voltage during eachphase falls between the window set up by the two comparators for each signal.

3.4.4.5 Bucky motor

At the beginning of the exposure, the CPU checks that the grid is in its properposition using the bucky home signal coming from the BUCKY CONTROLboard. The proper position is just after the reversal of the grid direction. Afterthis and about 100 milliseconds before the exposure, the bucky on signal (pin 7of X1) goes high, which pulls the relay K1 and thus connects the bucky motorto the BUCKY CONTROL board.

The BUCKY CONTROL board uses a photo interrupter to sense the positionof the grid. The input photodiode of this sensor is connected between pins 5and 6 of X3, and the output photo-transistor is connected across pins 3 and 4 ofX3 on the board. During the normal speed, the phototransistor conducts andthus grounds the base of transistor V7 and connects the bucky motor to theadjustable output of A1. Just before the change of the grid direction thephototransistor stops conducting, and the bucky motor is connected to a highervoltage through relay K2 thus making the change of the direction as quick aspossible. After the change the speed returns to normal again. After theexposure the grid is driven back to the proper position.


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3.4.5 Automatic exposure control (AEC)

3.4.5.1 AEC - general

There AEC consists basically of three parts to the circuit, the DETECTOR, theAEC board and the CPU board.

3.4.5.2 The Detector

The detector is a package containing 34 diodes connected in parallel. As X-raystrikes the diodes, they begin to leak current from the cathode to anode. Theamount of current each diode leaks is related to the amount of X-ray itreceives. Since the diodes are connected in parallel, the total current draw ofthe detector is the total of all diodes current draw.

3.4.5.3 AEC BOARD

There are four basic connections to the AEC board. The main power isconnected to X1, unregulated +18VDC supply to X1/1, analog ground to X1/2and unregulated -18VDC supply to X1/3. The detector connects to X2(cathode), X3 (detector shield) and X4 (anode). The detector can be measuredas a diode.

The connector X6 is for static shield. The purpose of the shield is to protect thephototimer board from major electrical interferences and X-rays.

The CPU is connected with the phototimer through connectors X1/8(AUTOEXP, information from the CPU) and X1/7 (AECFRQ information tothe CPU). The CPU also provides the +5VDC supply through X1/5 = +5VDC,X1/6 = ground.

The signal from the detector is taken to the first amplifier ICA1 which is thepreamplifier. Besides amplifying it also does the current to voltage conversion.Trimpot R2 is for adjusting the offset voltage of ICA1.(NOTE: adjusted to 0 - offset in the factory)


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The second amplifier A2 has a smaller gain which is adjustable to take intoaccount differences between detectors, x-ray tubes and film/screencombinations. Trimpot R6 is for adjusting the offset voltage of A2.(NOTE: adjusted to 0 - offset in the factory)

The AEC board replaces the phototimer board in the units manufactured sinceDecember 1994). In the AEC board the signal from the detector is taken tovoltage to frequency converter after amplification. The software for this boardis 7.xx or higher (6.35 and 6.55 also). The CPU board needs to be of version1.2 or higher.

3.4.5.4 The CPU

The CPU board looks at the pulses from the AEC board. The frequency ofthese pulses represents the radiation through the breast. The CPU converts thefrequency into a variable called INTEGRATION time. The microprocessorplugs this time into a formula and calculates the exposure time. Integrationtime has a nonlinear effect on the exposure time, which is important to keep inmind when making adjustments.


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3.5 DESCRIPTION OF CONTROL ELECTRONICS

3.5.1 Mains transformer and SUPPLY board

220V

240V

260V

24V

18V

15V

220V

240V

260V

24V

24V

T1 T2

Figure 3.5.1 Mains transformer connections

The SUPPLY board supplies all the voltages that are not used to produceX-rays. The collimator bulb voltage is on newer models regulated with a triacand why the voltage should be measured with the voltage meter at theAC-range.

3.5.2 CPU board

A block diagram of CPU board is in figure 3.7.

Intel 80C32 (in version 1.07 and below 80C31) (ICD1) microprocessorrunning at a clock frequency of 12 MHz is used as the nucleus of the CPUboard.

Port 0 of the processor is used as a combined data bus and the lower half of theaddress bus. Port 2 is used as the upper half of the address bus. Circuit ICD27(74HC373) latches the address code into the address bus when the externalmemory fetch is used. Circuit ICD21 (74HC245) with programmable GateArray Logic (GAL) circuit ICD22 (22V10), ICD7 (74HC32) and processorsignals PSEN,ALE, WR and RD control the direction of data transmission inthe data bus/lower half of the address bus.

Because the EA-pin of the processor is tied low, all the instructions are fetchedfrom the external memory. The printed circuit board includes three IC-socketsfor program chips. One is for the program memory circuit (ICD16) and thesecond is for static RAM circuit (ICD14). The third is for a nonvolatilememory EEPROM (ICD15).


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ICD22 (GAL 22V10) is used as an address decoder for data memory andI/O-circuitry (ICD8, ICD12, ICD13, ICD18, ICD19, ICD23, ICD26 and half ofthe ICD5). The address-map of the system can be presented:

0000 - FFFF program memory (64k)

8000 - 9FFF nonvolatile memory (8k)A000 - CFFF I/OD000 - EFFF data memoryF000 - FFFF not used

ICD8 (8279) is a keyboard/display controller which independently takes careof user interface and displays of the unit.

CPU has six 8-bit I/O ports. Three of them is configured as inputs and the restthree as outputs

The RESET and WATCHDOG circuitry consists of ICA2 (TL7705A).


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3.5.3 DISPLAY BOARD

The block diagram of DISPLAY board is presented in figure 3.5.3

KEYBOARD/

DISPLAY

CONTROLLERSEGMENT

DRIVERDISPLAYS

AND

LEDS

DIGITSELECT

KEYBOARD

Figure 3.5.3 Block diagram of DISPLAY board

The DISPLAY board is located in the control box and is connected by a cableto the controller circuit D15 (8279), which is located in the CPU board.

This board includes circuits D1 (ULN2003A), D2 and D3 (74H

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