stat fax 300series

Rev C 53

300 Series Service Manual© 1995-1996 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted foruse by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.

300 Series Strip ReaderService Manual

© 1993-1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted foruse by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair service. No partof this manual may be copied or redistributed without the express consent of Awareness Technology, Inc. There is no transfer of technology,copyright, trade name, patent, trade secret, or other proprietary right given or implied.

Rev C 11/04

Table of Contents

Introduction .................................... 1Layout ............................................. 2

Principles of Operation ................. 8Photometer ...................................... 8Display, Keypad, and Printer .......... 8System Control ................................ 8Carrier Position Detection ............... 9

Troubleshooting ...........................12Power Supply ................................ 12Photometer .................................... 12Strip Drive ..................................... 13Main PCB ..................................... 14Internal Printer ............................... 14Display .......................................... 14Keypad .......................................... 14Serial Port ...................................... 14Error Messages .............................. 17

Service Procedures .......................18Opening the Instrument ................. 18EPROM Replacement 20Lamp Replacement ....................... 22Filter Replacement ........................ 24Filter Label .................................... 26Printer Jams ................................... 28Printer Repairs ............................... 29

Print Head Replacement 29Printer Platen Replacement 31

Calibration ....................................32Software or Hardware Calibration?33Restore Calibration Data ............... 34

Diagrams .......................................35Block Diagram .............................. 35

PCB Layouts ................................36Main PCB - rev AB ...................... 36Main PCB - from rev Z ................. 37Main PCB – rev L to rev Y ........... 38Main PCB – through rev K ........... 39Printer PCB (300-200C) ............... 40Printer PCB (300-200) .................. 41

Schematics .....................................42Main PCB (rev AB) 1 of 4 ............ 42Main PCB (rev AB) 2 of 4 ............ 43Main PCB (rev AB) 3 of 4 ............ 44Main PCB (rev AB) 4 of 4 ............ 45Main PCB (from rev Z) 1 of 4 ...... 46Main PCB (from rev Z) 2 of 4 ...... 47Main PCB (from rev Z) 3 of 4 ...... 48Main PCB (from rev Z) 4 of 4 ...... 49Photometer PCB ........................... 50Printer PCB ................................... 51

Rev C 1

300 Series Service Manual© 1995-1996 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted for

use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.

IntroductionThis manual describes service and troubleshooting procedures for 300 series instruments. This manual

is written with the service technician in mind, and contains no information for clinical chemistry

analysis, or other applications. For details on instrument operation and specifications, please refer to

the Owner's Manual specific to the instrument.

There are presently two types of 300 series instruments in field use. Both types are equipped with either

a four optical filter photometer configuration or a six optical filter photometer configuration depending

on customer requirements. One type features a single microtiter strip handling device (hereafter

referred to as “Strip Reader with Spring Clip”) and the other type can accommodate up to three

microtiter strips using a different handling device (hereafter referred to as “Strip Reader with Three-

Position Carrier”). Both types of readers will accommodate either 8-well or 12-well strips. The Strip

Reader with Three-Position Carrier is supplied with a strip carrier which will accommodate 12-well

microtiter strips. An 8-well plate carrier is available as an option. Figure 1A illustrates a Strip Reader

with Spring Clip and Figure 1B illustrates a Strip Reader with Three-Position Carrier.

All types of the Model 300 series feature an internal thermal printer which provides a printed record

of all samples and test parameters. All calibration data, test parameters, and other information is stored

in battery-backed (nonvolatile) RAM.

2 Rev C



LayoutFigures 1A and 1B show the exterior of the single-strip and triple-strip style instruments. Figure 2

shows the rear panel. Figure 3 shows the bottom (both styles) of the instrument. Figure 4A shows the

internal chassis layout for the single-strip style instrument and Figure 4B shows the internal chassis

layout for the triple-strip style instrument.

The instrument housing is comprised of a chassis (base and rear panel combined) and a formed plastic

cover. The cover is secured to the base by five #4 self-tapping screws.

A 16 character alphanumeric LED display is mounted to the inside of the cover. A 20 column thermal

printer and the printer PCB mount to a metal printer bracket, which in turn mounts to the inside of the

cover. The display and the printer assembly both connect to the main PCB via 14 conductor ribbon

cable terminated with DIP (dual in-line pin) plugs. The keypad is a membrane-switch type sealed

beneath a graphic overlay and connects to the main PCB by the 8 conductor extension of the switch

layer, referred to as the “keytail”. The serial port connector (DB-9P) is mounted to the rear panel and

connects to the main PCB with a 4 conductor cable and SIP (single in-line pin) header.

The strip mechanism assembly (including the photometer) connects to the main PCB via a 14 conductor

ribbon cable and DIP plug as well as a 10 conductor ribbon cable and header. The 12VDC cooling

fan is mounted to the chassis base and connects to the main PCB via a 2 conductor cable and SIP header.

All AC mains components are mounted on the chassis.

The EPROM is located beneath a hatch on the underside of the instrument to facilitate easy software

upgrades. Early models which do not incorporate the EPROM hatch require the removal of the cover

for software upgrade.

CAUTION

Disconnect AC power cable before servicing.

Rev C 3



Your particular instrument may differ from the configuration described in this manual. To describe

each instrument model in detail would be impossible due to space limitations. Omitted features may

be ignored. Differences which affect service procedures are noted where applicable.

300 series variations:

• 4 or 6 - position filter wheel

• Thermal printer omitted

• Graphics printer assembly

• Printer assembly mounted to main PCB

• Non-removable power cord installed

• Serial port omitted

• EPROM hatch omitted and EPROM mounted to component side of main PCB

• EPROM device may be one of:

27128 16K bytes

27256 32K bytes

27512 64K bytes

• RAM device may be one of:

6116 2K bytes volatile

48T08 8K bytes nonvolatile, memory-mapped clock

DS1243 8K bytes nonvolatile, serial clock

• PCB revisions–installed components, locations, and jumpers:

Revisions A through K - see “Main PCB - through rev K” under “PCB

Layouts”

Revisions L through Y - shown in illustrations, also “Main PCB - Revisions

L through Y” under “PCB Layouts”

Revisions Z and higher - see “Main PCB - from rev Z” under “PCB

Layouts”

4 Rev C



Figure 1A. Instrument Exterior

Strip Reader with Spring Clip

Figure 1B. Instrument Exterior

Strip Reader with Three-Position Carrier

Display

Printer

Paper roll cover

Strip holder

Strip track

Keypad

Paper roll cover

Keypad

Display

Printer

Strip Carrier

Strip track

6 Rev C



Figure 4A. Chassis Layout

Strip Reader with Spring Clip

Power

transformer

Strip mechanism

Strip track

Strip

holder

Lamp

bracket

Filter

wheel

motor

Yellow wires

to Strip

Mechanism1

Main PCB

1 Only on Main PCBs from rev Z

Rainbow

Ribbon

Cable to

Strip Mecha-

nism

J8

(test

points)

Gray

Ribbon

Cable to

Strip

Mechanism

EPROM

(underneath main PCB)

Fuse blockStrip drive motor

Rev C 7



Figure 4B. Chassis Layout

Strip Reader with Three-Position Carrier

Strip mechanism

Strip track

Shuttle

Lamp

bracket

Filter

wheel

motor

Main PCB

Yellow wires

to Strip

Mechanism

Rainbow

Ribbon

Cable to

Strip Mecha-

nism

J8

(test

points)

Gray

Ribbon

Cable to

Strip

Mechanism

EPROM

(underneath main PCB)

Fuse block

Strip drive motor

Power

transformer

8 Rev C



Principles of OperationPhotometer

Light from a tungsten-halogen lamp mounted on a bracket above the strip track passes downward

though the well and the sample it contains. The sealed box beneath the sample contains a rotating filter

wheel and photodetector (GaAsP photodiode). The filter wheel contains optical band-pass filters at

selected wavelengths, and is speed controlled, via drivers U9A and U9B in parallel, to approximately

4 rps. As each filter passes in front of the photodiode, a precisely located index hole in the filter wheel

in tandem with an infrared optical switch generates a pulse (FCNT) at U13. Sample-hold capacitor C14

charges to the peak voltage produced by the photodetector and amplifiers U16 and U14B. The sampled

voltage is buffered by U15A and then fed to comparator U15B which compares the sampled voltage

to the output of an exponential capacitor decay circuit built around Q3 and C16. The positive voltage

at the comparator output enables a counter in 8254 timer U4, the value of which is ultimately read by

the microprocessor and used to compute the absorbance. The photodetector output is proportional to

the intensity of the light, whereas the width of the positive phase of the comparator output is proportional

to the absorbance. An oscilloscope can be used to view the important signals at connector J8 while the

instrument is in operation. See Figure 6, Oscilloscope Waveforms.

A DC motor under microprocessor control drives a lead screw via a pulley and neoprene belt. The lead

screw moves the strip holder along the strip track. The pulley incorporates indexing holes so that an

infrared optical switch generates pulses (CLK2) to timer U4 from which the microprocessor derives

position and speed of the strip movement. The movement is zeroed at the front extreme when the motor

stalls. Each well in the microtiter strip can thus be precisely aligned with the photometer assembly.

Display, Keypad, and PrinterA 16 character alphanumeric LED display is mounted inside the cover. The display connects to the

Z80 data and address buses on the main PCB via a 14 pin DIP cable, which also supplies +5VDC

power. A 4 x 4 membrane switch keypad is sealed behind the front panel overlay. The tail of the keypad

switch layer is fed through the cover and installed to connector K1 on the main PCB, which then

connects to 8255 PPI U5. The printer assembly, consisting of a 20 column thermal printer, the printer

PCB, and metal support, is mounted to the cover and is connected to the main PCB via a 14 pin DIP

cable, which provides +5VDC power and the control lines from U5. On early models the printer

assembly is mounted to the main PCB with threaded spacers.

System ControlThe instrument is based on the 8 bit Z80 microprocessor U1, using a 2MHz clock. The software is

permanently stored in EPROM U2. Battery-backed NVRAM (nonvolatile random access memory)

U3, incorporates a real-time clock mapped to the uppermost 8 bytes. Some early models used an

NVRAM with a serial-access real-time clock (DS1243Y). The NVRAM is used store test setups. Most

digital I/O is accomplished with 8255 PPI U5. Time intervals and pulse widths are measured using the

counter channels of 8254 timer U4.

The memory map shown below is for a 27256 EPROM and a 48T08 NVRAM. See the jumper

settings table below for other configurations

Rev C 9



Carrier Position DetectionThe latest configuration instrument features the ability to read three microtiter strips instead of a single

strip as in earlier models. Earlier models detected the position of the first well. The three - position

carrier configuration uses indexing holes located on the carrier to distinguish between the adjacent

strips. As the carrier moves forward the instrument looks for the front edge of the carrier which blocks

light to the Photometer. A predetermined distance between the edge of the carrier (light blocked) and

the index hole (light sensed) gives the control circuitry the information it needs to determine if the carrier

is positioned to read the left or center strips. In the case of the right strip, no index hole is used and the

control circuitry is programmed so that if light is not sensed in either of the two other programmed index

hole locations (the light continues to be blocked) the carrier is positioned to read the right strip.

The position of the carrier relative to each well in a microtiter strip is tracked by counting pulses obtained

from the pulley which drives the threaded shaft which moves the shuttle (and carrier) along the guide

tracks. When the front edge of the carrier is sensed, a reference position is established.

10 Rev C



300 Series typical memory map (see jumper settings table)0000:7FFF EPROM8000:9FF7 NVRAM9FF8:9FFF real-time clock

300 Series I/O map (fixed)00:03 8255 PPI U5

00 Port A01 Port B02 Port C03 Control Word

10:13 8254 Timer/Counter U410 Timer 011 Timer 112 Timer 213 Control Word

20:2F Alphanumeric LED Display (each I/O address maps to a character position)

300 Series Jumper Settings

PCB Rev through F:no jumpers

PCB Rev G through K:27128 27256 6116 48T08/DS1243 M E R

x x 1-2 2-3 1-2x x 1-2 2-3 2-3

x x 1-2 1-2 1-2x x 2-3 1-2 2-3

PCB Rev L through U:27128 27256 6116 48T08/DS1243 M E R

x x 1-2 1-2 1-2x x 1-2 1-2 2-3

x x 1-2 2-3 1-2x x 2-3 2-3 2-3

PCB Rev V through AA27128 27256 27512 6116 48T08 M E1 E2 Rx x 1 1-2 2-3 2-3

x x 2 1-2 1-2 1-2x x 3 2-3 1-2 1-2

Rev C 11



Figure 5. Troubleshooting Flowchart

12 Rev C



TroubleshootingThe flowchart in Figure 5 describes the logical steps to take if the instrument is malfunctioning. It is

only a guide to troubleshooting, and is intended to assist in determining routine problems. It is not

intended to take the place of an experienced technician, nor does it attempt to cover all possible

problems.

In the following section, each subassembly or component group and possible problems and solutions

are outlined.

Power SupplyThe power supply consists of a transformer, two diode bridges, and three regulators. Line voltage

supplied to the transformer is converted to 36 VAC, center tapped, which feeds diode bridge BR2. The

center tap is used as a reference for regulators VR4 and VR5, which provide +15 VDC and -15 VDC

for analog circuitry. Another transformer output supplies 11VAC to diode bridge BR1, which in turn

provides +12 VDC (raw, 11-13 VDC nominal) to the system, and VR3 regulates this down to +5 VDC

for the logic and other low voltage control circuits.

A “dead” instrument may be just a blown fuse. However, a blown fuse may indicate a problem on the

main PCB or transformer such as a shorted bridge rectifier or transformer winding. Also, the voltage

select switch setting must match the line voltage. If there is no input voltage present at J6, check the fuse.

To replace the fuse, disconnect the power cable and open the instrument. Locate the double clip fuse

holder mounted on the inside of the rear panel. Locate the blown fuse and remove it with a fuse puller,

or carefully pry it out with a small screwdriver. Install two (2) 0.5 A 3AG slow-blow fuse. Use only

the recommended fuse. Do not substitute any other rating!

If voltage is present at J6, check for input voltage on VR3, VR4, and VR5. If no voltage is present, the

diode bridge BR1 or BR2 may have failed.

PhotometerThe photometer assembly can be examined as several component systems:

• Lamp• Filter wheel• Photometer• Strip drive mechanism

The lamp is tungsten gas-filled, with integral lens end, rated at 6V 6W. The lamp bracket holds the lamp

in alignment with the rest of the assembly, that is, the lens end of the lamp is centered on the optical path.

The lamp is intended to be maintenance free for the life of the instrument, since the lamp is turned off

automatically after 30 minutes of instrument inactivity. Under heavy usage the lamp remains on for

longer periods and so may require replacement. Also, a physical shock to the instrument could cause

filament breakage.

Rev C 13



The lamp must be replaced if output becomes low or the lamp fails completely. Since the light is visiblewithout removing the instrument cover, the case of no lamp output can be observed from outside theinstrument. Sight down the strip track while the instrument is first powered on. To check for low output,select test #186. The instrument prints the wavelength, position, and the detected voltage for each filter.The voltages should be between 2 and 10 volts. If all of the voltages are below 2.0 volts, the lamp isthe likely suspect. As a final check, measure the voltage at the lamp terminals. If the lamp voltage ismuch lower than 5.5 VDC, the regulator circuitry on the main PCB (Q6 and VR1) may be the problem.Otherwise, replace the lamp. Refer to the section “Lamp Replacement”. Never adjust trim pots onthe Main PCB to achieve the proper voltages.

If only one or two filters report low detected voltages, degraded filters or an improperly adjusted lampmay be the cause. To check for an improperly adjusted lamp, refer to Figures 10 and 11, as well as theprocedure “Lamp Replacement”. The optical interference filters contained in the wheel are of metal-deposition type construction and are intended to be maintenance free for the life of the instrument. Someolder instruments incorporated other filter materials whose transmittance can be reduced dramaticallyif subjected to high humidity over very long periods. Refer to the section “Filter Replacement”.

The filter wheel turns on a shoulder screw shaft and is driven by the filter wheel motor via a neoprenebelt. The filter wheel itself requires no adjustments. Indexing holes in the filter wheel generate pulsesvia LED/phototransistor pairs, which synchronize photometric readings and provide feedback to themicroprocessor of the filter wheel speed. The photometer contains a photodiode, a high-gain op ampcircuit (U16) and phototransistors Q7 and Q8. Because the photodetector and related circuitry is solid-state, it should require no service. Avoid unnecessary handling of the photometer PCB or removal of

the optical cover.

Strip DriveThe strip drive mechanism is a 1/4-20 lead screw driven by a 12 VDC motor via a belt and pulley.Indexing holes in the pulley serve to generate tach pulses via an LED/phototransistor pair, which aremonitored by the microprocessor. To establish a reference position, the strip holder is moved forwardalong the strip track until the motor stalls. As the strip holder is moved back along the strip track, pulsesare counted to derive the position relative to the stall point. Any problem with the strip mechanism isimmediately apparent as a lack of strip movement, or noisy or erratic movement. A total lack of stripmovement could be the tach generator, motor driver U10 failure, or motor failure. Check the opticalswitch pair (LED/phototransistor) mounted next to the pulley. You should see pulses at CLK2 (U4.18)when the motor is running. Ensure that the LED and phototransistor are aligned with the holes in thepulley. Check for voltage at the motor terminals and at driver U10.

For older instruments, lubrication or adjustment of the lead screw is indicated for noisy or erraticmovement. This should only be necessary at 3 to 5 year intervals, depending on service conditions.Lubricate only the o-rings and shoulder washers at each end of the lead screw. Do not lubricate the stripholder shuttle or the lead screw threads.

If strip position errors are chronic, lead screw end play may require adjustment. Grasp the pulley andmove the lead screw along its axis. End play should be less than 1mm. To adjust end play, the pulleyposition along the drive screw must be adjusted. The drive pulley will be retained by a thumb nut orset screw depending on when it was manufactured. Loosen the nylon thumb nut or loosen the set screw(access via the pulley groove) holding the pulley. Turn the pulley on the lead screw to remove end-play. Do not tighten the pulley against the o-ring spacer. Hold the pulley and tighten the thumb nut orset screw. Recheck end play and repeat if needed.

14 Rev C



Main PCBUnder normal circumstances, there are no adjustments to be made to the main PCB. Circuit failures

are highly unlikely, but if they occur, it is recommended that the repairs be performed by factory

authorized technicians. There are ten test points on J8 which provide access to a number of vital signals.

The instrument can be observed in operation with an oscilloscope. Typical test point waveforms are

shown in Figure 6. Note that Figure 6 shows a 6 position filter wheel. The 4 position filter wheel is

very similar.

Internal PrinterThe internal printer is a 20 column thermal type device which prints ASCII characters using a 5 x 7

dot matrix. A printer PCB, incorporating a dedicated microcontroller, manages the print head motor

and the head drivers. There are no adjustments, and service is limited to replacement of the entire printer

mechanism. A printer jam can occur if the printer paper tears and becomes lodged in the printer

mechanism, thus preventing the print head from moving freely. Refer to the section “Printer Jams”.

DisplayThe display should be clearly legible with no missing or dim characters or segments. There are no

adjustments, and service is limited to replacement.

KeypadThe keypad is a sealed membrane switch layer which is serviceable only by replacement. You can test

the keypad by pressing AUX, then pressing all keys except CLEARandENTER. Note that each

key causes the instrument to beep and display a character. Press CLEARand the display clears. Press

ENTER to end the test.

Serial PortThe serial port is intended for use with an external serial printer. Early models do not support a serial

printer. By using a special cable, a serial printer or other serial device may be connected. This is a male

9 pin DB-style connector using RS-232 signals in a nonstandard pin-out. The data format is 2400 baud,

8 bits, 1 stop bit, and no parity.

Serial port pin-out

1 GND

2 TX

3 RX/DTR

4-9 NC

Rev C 15



Figure 6. Oscilloscope Waveforms

16 Rev C



NOTE

The mechanism for the Strip Reader with Three-Position Carrier will

look somewhat different. The motor which drives the Photometer

wheel will also be on the bottom of the mechanism.

Figure 7. Strip drive mechanism (bottom)

Photometer cover

Pulley

Strip drive

motor

Lead screw

O-ring

spacer

Cap nut

Thumb

nut

Optical

switch

Rev C 17



Error MessagesError messages are displayed when the instrument fails to operate correctly. They are intended to help

the operator locate the problem. If error messages appear frequently, a hardware problem is usually

indicated.

The following error messages indicate possible interface or component problems.

LAMP OUTPUT IS LOW!! Low voltages were detected for all filter positions., The instrument

assumes this to be a result of low lamp output. This may be due to a

failing or misaligned lamp, degraded interference filters, or voltage

regulator VR1 failure.

LAMP FAILURE The lamp does not appear to illuminated at all. Very low voltages

were detected for all filter positions. See the section “Photometer”

under “Troubleshooting”.

PRINTER JAM The internal printer paper path is obstructed. Clear the paper path. If

the paper path is clear, Check the 14 pin DIP cable connecting the

printer PCB to the main PCB.

FILTER WHEEL STOPPED The instrument cannot correctly detect pulses from the filter wheel.

Check the photometer LED board and the phototransistors Q7 and

Q8 on the photometer PCB. See the section “Photometer” under

“Troubleshooting”.

MECHANISM ERROR The instrument was unable to correctly position the strip for reading.

This may result from a stalled drive motor, lead screw improperly

adjusted, failed driver U10, or motor failure.

POSITIONING STRIP The instrument is attempting to position the strip for reading. If this

message is displayed continuously, the mechanism may have jammed.

See “MECHANISM ERROR”.

The following error messages indicate possible loss of battery power in the NV RAM U3, which can

be checked by substitution and power cycling.

MEM ERR-TEST ENDED The checksum failed when a stored test was recalled. The test was

canceled.

FILTERS RESET Programmed filter wavelengths for key 5 and key 6 were found to be

corrupted. Run test # 248 to reprogram the filter wavelengths. Refer

to filter label and Figure 13. Filter wheel position #3 corresponds to

key 5 and filter wheel position #2 corresponds to key 6.

DO ABS SET TEST 212! The stored absorbance calibration values were corrupted or not

found. Restore the calibration data. See the section “Calibration”.

18 Rev C



Service Procedures

Opening the InstrumentThe cover must be removed to allow access to the inside of the instrument. Disconnect the power cable

and the serial cable (if connected) from the rear panel. Invert the instrument on a soft nonabrasive

padded surface such as a terrycloth towel, to prevent scratching. Refer to Figure 3, Chassis Bottom.

Locate and remove the (5) cover screws from the bottom of the instrument. Do not remove or loosen

any other screws. While holding the instrument cover in place with both hands, return the instrument

to the upright position.

On some models, the printer mechanism is mounted to the main PCB and the printer paper roll must

be removed to allow cover removal. Press inward on the sides of the paper roll cover and lift it off. Lift

out the paper roll and tear off the paper where it enters the printer mechanism.

Grasp the cover at the left side. Gently lift the cover upward and to the right, until the cabling is visible.

You can rest the cover on its right-hand side while you disconnect the cables. Refer to Figure 8, Cover

Connections. Disconnect the display cable at the left front of the main PCB assembly. Place a small

slot blade screwdriver between the 14 pin DIP plug and its socket and pry gently upwards. Do not bend

the pins. Disconnect the printer cable in the same way. Disconnect the keypad cable from its connector.

Remove the cover and set it aside.

To reinstall the cover, reverse the procedure. Position the cover on its side to the right of the chassis base.

Connect the printer, display, and keyboard cables. Carefully fit the cover to the chassis base. Install

the cover screws. Do not overtighten the cover screws.

WARNING

Hazardous line voltages are present on the rear panel.

Always disconnect the AC power cable before opening the

instrument.

Rev C 19



Figure 8. Cover Connections

Main PCB

Red stripe

To display

To printer

To keypad

Red stripe

Remove and install

DIP plugs vertically.

Do not bend pins.

Remove and install

keypad cable verti-

cally. Do not twist,

kink or fold the key-

pad cable.

20 Rev C



EPROM Replacement

The instrument software can be upgraded to the latest version by replacing the EPROM. On most

instruments, the EPROM is accessible through a hatch on the underside of the chassis, and can be

changed without removing the cover. On older instruments, the EPROM is accessible only by

removing the cover.

1. Refer to Figure 3. Locate the EPROM hatch on the underside of the instrument. Place the

instrument upside down on a soft surface. Remove one hatch screw and loosen the other.

Swing the hatch out of the way. If the instrument has no EPROM hatch, remove the

instrument cover.

2. Refer to Figure 9. Locate the EPROM socket and lift the small lever at the end of the socket.

This frees the EPROM for easy removal and insertion. If the EPROM socket has no such

lever, pry out the EPROM with a small screwdriver or other tool. Do not bend the EPROM

pins.

3. Gently bend the pins on the new EPROM as shown below, so that the pins are perpendicular

to the EPROM. Hold the EPROM by the body and bend the pins against a flat surface such

as a table to bend all the pins the same amount. Do not over bend the pins, since they are easy

to break if bent too far.

4. Install the new EPROM with the notch or dot (indicating pin 1) oriented toward the front of

the instrument. Press the lever down toward the PCB until it locks into place.

5. Replace the hatch screw removed in step 1, or replace the instrument cover if removed.

6. Power up the instrument and verify that the instrument operates with the new software.

Rev C 21



Figure 9. EPROM Replacement

Lever (also on underside of PCB)

EPROM

socketed to under-

side of PCB, acces-

sible via hatch on

chassis bottom

EPROM accessible

by removing

instrument cover

Lever

22 Rev C



Lamp ReplacementThe lamp should be replaced only if it fails to light, or several filter voltages are reported as low.

Materials and equipment:• Replacement lamp• Phillips screw driver• Flat blade screw driver

Procedure:

1. Set the power switch to OFF (O). Open the instrument. Refer to Figure 4A or 4B (ChassisLayout) as appropriate for the instrument. Locate the strip mechanism and the lamp bracket.

CAUTION

Lamp is HOT. Allow the lamp to cool before handling.

3. Refer to Figure 10, Lamp Replacement. Remove the Lamp Bracket Mounting Screws (onlyif necessary to access the lamp!) and lift the Lamp Bracket away from the Guide Bracket.Loosen but do not remove the lamp terminal screws. Do not loosen or remove any otherscrews. Remove the lamp from the connector.

4. Use a pair of pliers or tweezers to handle the new lamp. Avoid handling with bare skin, sincethe oil from your skin can reduce lamp life. Insert the lamp leads into the connector until theybottom out. Re-screw the Lamp Bracket to the Guide Bracket if removal was necessary. Thelamp lens end must be centered on the aperture and the lamp body must be perpendicular tothe horizontal. While holding the lamp in alignment, tighten the lamp terminal screws.

5. Set the power switch to ON. Shield your eyes from the lamp beam and observe the projectionof the beam onto the aperture. Refer to Figure 11, Spot Alignment. The spot should be smalland centered on the aperture. The spot should be sufficiently large to just encircle the aperture.If the spot is not centered, repeat step 4.

6. Select test #186. The instrument prints the detected voltage for each filter position. Allvoltages should be between 2.00 volts and 10.00 volts. If all the voltages report low, repeatstep 4 until optimum lamp position is obtained. Never adjust trim pots on the Main PCBto achieve the proper voltages.

Rev C 23



Figure 10. Lamp Replacement

Figure 11. Spot Alignment

Mounting

Screws

Lamp

bracket

Lamp

LAMP MOUNTING CONFIGURATIONS

Lamp

terminal

screws

Aperture

Guide

bracket

Lamp

connector

Lamp must be perpendicular to guide bracket and

projected spot must be centered on aperture.

Spot

Aperture

Projected spot must be bright,

well-focused, and centered on

aperture.

24 Rev C



Filter ReplacementMaterials and equipment:

• Replacement filter set• Phillips screw driver• Flat blade screw driver

Procedure:1. Open the instrument. Refer to Figure 4A or 4B as appropriate for the instrument. Locate the

Strip Mechanism and the ribbon cables which run from the Main PCB to the Strip Mechanism.Unplug both ribbon cables from the main PCB. On units using Main PCB rev Z and subsiquentrevisions, a third set of wires (two yellow wires connected to J17) need to be disconnected.

2. Use a pencil to mark the front and side edges of the photometer on the chassis so that thephotometer can be installed in its original position.

3. Refer to Figure 3. Locate the (2) #6 screws holding the Strip Mechanism assembly to thechassis. From the bottom of the instrument, remove these screws and washers while notingthe screw lengths and locations from which they were removed. Remove the StripMechanism.

4. Orient the Strip Mechanism so that you are looking at the bottom of the assembly. Refer toFigure 7, Strip drive mechanism, and Figure 12, Filter Replacement. Remove the four 6-32screws retaining the photometer cover. Set the photometer cover aside.

5. Remove the two 4-40 screws securing the photometer PCB. Gently move the PCB asidewithout disconnecting any wires.

6. Remove the belt from the filter wheel and pulley. Loosen the shaft (shoulder screw). Removethe shaft and filter wheel. Note the number of nylon washers and the order of installation.

WARNING

Retaining Rings (used on later production filter wheels) willpop out from filter wheel when its spring tension is released

during removal. Shield the opening with hand and wearsafety glasses.

7. Refer to Figure 13, Filter Wheel Positions. Locate the filter(s) to be removed. There arecurrently two means of filter retention in field use; silicone glue or a Retaining Ring. Referto Figure 12 and determine if a Retaining Ring is used. If a Retaining Ring is used, carefullypry two to three of the retaining ring teeth away from the filter until the ring is dislodged andremove the ring and filter. If silicone glue is present, remove the silicone and push the filterout of the wheel using the eraser end of a pencil or other soft blunt object and the glue shouldrelease. Remove any remaining filter components from that position in the wheel.

8. Locate the neutral density filters, dot screen, and transmittance filters that were included withthe replacement filter and drop them first into the cavity. Install the interference filter with themirror side down. Place the replacement retainer over the filter so that the tabs are angled awayfrom the filter and press in place with a 7/16 diameter wooden dowel or similar object.

9. Install the filter wheel taking care not to pinch washers under the shaft. Reassemble the shaftand washers as disassembled. Tighten the shaft securely. The filter wheel should spin freely.

10. Install the filter wheel belt. Be sure that the belt is centered on the filter wheel and is not twisted.

11. Install the photometer PCB taking care to center the board around the shaft.

12. Replace the photometer cover, taking care to position the cable in the slot of the cover. Donot pinch the cable under the cover. Tighten cover screws only until snug. Do not overtightenthe photometer cover screws! Doing so will bend the photometer cover and create lightleakage.

Rev C 25



13. Install the Strip Mechanism to the chassis by replacing the (2) #6 screws removed in step 3through the chassis base in their original locations. Line up Strip Mechanism with locatingmarks made in step 2. Connect the cables removed in step 1.

14. Attach the power cord and connect the instrument to the mains supply. Set the power switchto ON (1). Select test #186. The instrument prints the detected voltage for each filters. Allvoltages should now be between 2 and 10 volts. If not, check lamp alignment. If the lampalignment is properly set, the neutral density filters may need to be changed. Add neutralsto lower the voltage. Remove neutrals to increase the voltage. Never adjust trim pots on theMain PCB to achieve the proper voltages.

Figure 12. Filter Replacement

Remove Screws holding

photometer cover.Remove screws holding

photometer PCB.

Filter wheel Belt

Pulley

Shaft

Filter

Retainer

Remove filter wheel

belt and filter wheel. Remove adhesive or

retainer and push

filter from wheel.

Install neutral density filters,

dot screens, interference filters

and retainers.

One nylon

washer

One or two nylon washers

as disassembled.

Assemble washers and filter

wheel to filter wheel shaft.

26 Rev C



Filter Label

The filter label located on the photometer cover describes the specific filter wheel configuration for your

particular instrument. Refer to Figure 14.

Filter wheel position (POS) is the physical placement of the filter on the wheel and does not correspond

directly to the key position. The filter wheel position numbers are shown in Figure 13. Note the position

of the Index hole and the Home hole. When running test # 248, note that filter wheel position #3

corresponds to key 5 and filter wheel position #2 corresponds to key 6.

Each filter position can have several filter elements installed. Configuration (WAVELENGTH

column) describes the various screens and filters in that position . Each element is separated by a slash

(/). The first 3 digit value in this column is always the wavelength of the interference filter, in

nanometers. The other values indicate either dot screens, neutral density filters, or transmittance filters.

A “D” suffix indicates a dot screen and the first two digits are the percent blockage. A 2 digit value

followed by a percent sign signifies a dot screen. A 3 digit value (other than the first value in the line)

indicates one or more transmittance filters. The first digit is the quantity; the last two digits are the

percent transmittance. A 2 digit value separated by a decimal point indicates a neutral density filter. The

value is the absolute absorbance of the filter. “BLOCKED” indicates an opaque disk is installed in

that position.

LOT# is the interference filter manufacturers' production code lot number or date. In the new style,

the percent transmittance for the lot is included in this column.

The production date (DATE) is the date the filter wheel was assembled.

Figure 13. Filter Wheel Positions

Home

hole

Index

hole

Home

holeIndex

hole

Rotation

6

5

4

1

2

3

1

23

4

4 Position 6 Position

Rotation

Rev C 27



Filter wheel

position

Configuration Production

date

Filter date or

lot number

Old style

POS WAVELENGTH LOT# DATE

1 405 3YGF 58.8% 5/23/94

2 545/90D/115/170 4GDB 80.6% 5/23/94

3 600/90D/115/170 3ZCJ 65% 5/23/94

4 492/215 3WEF 74.4% 5/23/94

5 630/215/15D 4FLR 67.6% 5/23/94

6 450/115/90D 4HDL 83% 5/23/94

New style

Figure 14. Filter Labels

POS WAVELENGTH LOT# DATE

1 405 2VCT 11/6/92

2 545/2.0/30% 6/30/92 11/6/92

3 600/2.0 8/10/92 11/6/92

4 492/1.0/70% 8/10/92 11/6/92

5 630/1.0/30% 8/10/92 11/6/92

6 450/80% 7/21/92 11/6/9

28 Rev C



Printer Jams

CAUTION

Do not apply force to the print head.

Do not scratch the platen or pry with sharp objects.

If the instrument displays “PRINTER JAMMED”, or if the print head does not return to the home

position, check for obstructions in the print head path.. Refer to Figure 15. Carefully remove any paper

or debris with a pair of tweezers. Turn off the power switch, wait 5 seconds, then turn on the power

switch. The print head should move to the right side and then return to home position at the left.

An alternate method of removing a particularly stubborn wad of paper is to move the print head

manually. To do this, open the instrument. Remove the two nuts holding the printer bracket to the

cover. View the front of the printer mechanism. Locate the small gear on the right side which turns the

grooved steel print head shaft. Turn the gear so that the print head moves away from paper wad and

the paper can be easily removed.

Figure 15. Clearing printer jams

Right front gear

moves print headPrint head shaft

Print head is jammed

against wad of paperHome

position

Print head

Rev C 29



Printer Repairs

A graphics capable printer has been introduced in recent instruments. Replacement printers are

graphics capable and can be made compatible with earlier non graphics capable printer PCBs. One way

to identify which type of printer is used is to remove the ribbon cable from the keytail socket on the

printer interface PCB. Look at the connector on the ribbon cable. An earlier non graphics capable

printer will have eight conductors. The graphics capable printer will have nine. Another way to identify

which printer is used is to look at the blue inspection label on the printer interface PCB. If the number

on the label is M020445 or higher, a graphics capable printer is used. Repairs to printer mechanisms

can consist of print head replacement or printer mechanism replacement.

Print Head Replacement Replacement Print Heads are supplied for the graphics capable printer (nine conductor ribbon cable).

Determine the size of the keytail socket on the Printer Interface PCB into which the ribbon cable from

the Print Head being replaced is inserted (eight or nine slots). If there are eight slots, modify the

replacement Print Head as shown in Figure 16.

If ribbon is too wide for socket,

orient as shown and trim through

center of pad as shown.

Wide trace

Figure 16. Replacement Print Head Modification for

Non Graphics Capable Printers

Refer to Figure 17 and replace the Print Head as follows:

1. Pry out the pin (1) which holds the gear (2) in place.

2. Remove the pin (3) from the side of the print head with tweezers and pry the pin (4) from thetop of the Print Head. The Print Head should now be free to move along the Drive Screw (6).

3. Remove the snap ring (5) from the end of the drive screw (6) and withdraw the drive screwand gear assembly from the printer mechanism in the direction shown.

4. Press the end of the slider rod (7) out of the hole in the printer mechanism in the directionshown from the left side of the mechanism. It is not necessary to remove the slider rodcompletely from the mechanism.

5. Slide the Print Head off the slider rod and replace with the new Print Head. Reassemble themechanism in reverse order of the above disassembly steps.

30 Rev C



Figure 17. Printer Views for Print Head Replacement

1

2

3

4

5

6

7

7

6

LEFT SIDE

RIGHT SIDE

Rev C 31



Printer Platen Replacement

1. Referring to Figure 18, remove the Paper Dress Cover.

2. Move the Print Head to the right-most position as shown by rotating the Screw Drive with itsdrive gear on the right side of the mechanism.

3. Lift out the left side of the platen.

4. Install the new platen so that the end which has the longer pin is oriented toward the right sideof the mechanism. Insert the right end of the platen under the print head. Use a pen point orsimilar blunt instrument to push metal spring slightly forward, then slip the left side of platenin place.

Figure 18. Printer Platen Replacement

Platen

(darkened area)

LEFT

SIDE

RIGHT

SIDE

Screw Drive

Dress Cover

Print Head

32 Rev C



CalibrationEach instrument is calibrated during manufacturing using standards that are traceable to the National

Institute for Standards and Testing (NIST), and is tested to verify its linearity to 2A. This preset

calibration is very stable, and the instrument should never require re-calibration during normal service

life.

Absolute calibration can be verified with the use of NIST filters, or by comparison to a reference

instrument that is known to be calibrated to NIST filters.

Since most lab test results are based upon standards rather than upon absolute absorbances, the linearity

of the instrument, rather than the accuracy, is the more critical indicator of instrument performance. A

periodic verification of instrument accuracy and linearity is advised. Calibration may be confirmed

using a commercially available photometer calibration check set which can be obtained from your

distributor.

CAUTION

RE-CALIBRATION OF THE INSTRUMENT

SHOULD NOT BE REQUIRED UNDER NORMAL

CIRCUMSTANCES, AND SHOULD NOT BE

CONSIDERED UNTIL ALL POSSIBLE

INTERFERING FACTORS HAVE BEEN RULED

OUT, INCLUDING CHEMISTRY ERROR,

OPERATOR ERROR, LAMP FAILURE, AND

DEGRADED FILTERS.

Standards and blanks should be closely checked for accuracy

and results should be compared with a reference instrument.

Use of a commercially available photometer check set to

verify photometric accuracy and linearity is strongly

recommended.

Restoring the factory calibration data should always be

attempted before resorting to Re-calibration.

Rev C 33



Software or Hardware Calibration?

Most instruments manufactured after June 1993 rely on software calibration, that is, on

calibration data stored in nonvolatile RAM. The calibration data is used by the instrument to

compensate for variations in electronic components. During factory calibration, any necessary

hardware adjustments are made using precision reference standards and specialized electronic

equipment. The calibration data is stored in the instrument memory and also recorded on a label located

on the bottom of the instrument. This requires no hardware adjustments.

The absorbance calibration data is stored as a scaling factor, which is the ratio of a known reference

absorbance to the instrument's reported absorbance. The value entered at the keypad is multiplied by

the stored value to obtain a new scaling factor. The calibration data may be printed at any time by

selecting test #213. This prints the serial number of the instrument, the date of last calibration, and the

stored absorbance scaling factor.

Calibration data is stored with a checksum that is recalculated and compared each time the instrument

is powered on, a new software mode is selected, or a stored test is recalled. Under certain circumstances,

large AC mains transients or other environmental disturbances may cause the microprocessor to

“crash” and possibly render the calibration data invalid. Failure to recover the calibration data properly

(checksum failure) will be indicated on the display and the internal printer as follows:

DO ABS SET TEST 212!

If this message is printed or displayed, it indicates that the calibration values have been lost. This

message will be printed each time the checksum failure occurs. The instrument also annunciates this

condition with multiple beeps. In this condition, the absorbance scaling factor is set to 1.000. The

maximum absorbance error is then +/-10%, provided the trimpots have not been disturbed.

The calibration data can be restored from the calibration label as described in the section “Restore

Calibration Data”.

All instruments manufactured before June 1993 utilize hardware calibration. This requires

making adjustments to the trimpots for absorbance gain and offset. If you believe your instrument

requires hardware re-calibration, contact your distributor for assistance. Never adjust trim pots on

the Main PCB to achieve the proper voltages.

To determine whether the instrument incorporates software calibration features, select test # 213. If

calibration data is printed, the instrument supports software calibration.

In any case, if the trimpots have been disturbed or components C16, R12, R16, R11, R13, RN8, R24,

U16, or the photodiode have been replaced, the instrument will probably require re-calibration. Contact

your distributor for assistance. Never adjust trim pots on the Main PCB to achieve the proper

voltages.

34 Rev C



Restore Calibration DataThis procedure restores the calibration data to the original factory settings recorded on the calibration

data label.

Procedure:

1. Select test #213 to print the calibration data. The instrument prints something similar to this(the actual value may differ):

ABS FACTOR 1.126

2. Select test #212. The display shows:

ABS FACTOR=

If the value printed in step 1 is not exactly 1.000, enter the inverse of the value printed in step1. That is, calculate

1 ABS FACTOR

and enter that value.

3. Locate the calibration data label on the underside of the instrument. Copy the data from thelabel for reference in the following steps.

4. If the date and time are incorrect, set the date and time as described in the Owner's Manual.

5. Select test #212. The display shows:

ABS FACTOR=

Enter the number from the Abs Factor line of the calibration label.

6. Select test #213 to print the calibration data. The printed data should now match the valuesshown on the calibration data label. If it does not, repeat this procedure.

Rev C 35



DiagramsBlock Diagram

36 Rev C



AWARENESS

TECHNOLOGY

300-100AB(AR)300MAINPCB995001

PCB LayoutsMain PCB - rev AB

Rev C 37



Main PCB - from rev Z

38 Rev C



Main PCB – rev L to rev Y

Rev C 39



TO

PHOTOMETER

TO

LAMP/MOTOR

Main PCB – through rev K

40 Rev C



Printer PCB (300-200C)

Rev C 41



Printer PCB (300-200)

42 Rev C



SchematicsMain PCB (rev AB) 1 of 4

Rev C 43



Main PCB (rev AB) 2 of 4

44 Rev C




Rev C 45




46 Rev C



Main PCB (from rev Z) 1 of 4

Rev C 47




48 Rev C




Rev C 49




50 Rev C



Photometer PCB

Rev C 51



Printer PCB

52 Rev C



Notes:

stat fax 300series

Documents

main pcb rev ab

main pcb rev ab

printer pcb

photometer pcb

pcb layouts

printer platen replacement

internal printer

printer jams