8/9/2019 Billion Router Wi Fi Repair

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Created by Chris Humphris

Page 1 9/07/2012

Procedure to Repair Billion 7404VNPX Routers with Wireless Problem

Introduction

The Billion 7404VNPX 3G/VOIP/ADSL2+/WiFi Router has had numerous recorded problems with theWireless Section failing. See Whirlpool threadhttp://forums.whirlpool.net.au/archive/1593502

Generally the failures occur following a period of inactivity with power off. The scenario is that the user goesaway for a break, and sensibly powers down the router whilst he/she is away. When they return from theirbreak, the router wireless section refuses to come back to operation, with all other functions operatingnormally. This condition is accompanied by the WirelessLED not illuminating on the front panel. Of coursethis happened to me.

This procedure outlines a process which results in restoring the router Wireless function.

Reason for the Failure Mode

My failure was caused by the total absence of printed circuit board cleaning during manufacture.Components on Printed Circuit Boards (PCBS) are generally soldered using a flux to assist with good jointwetting and solder flow. Fluxes are generally resin based (the stuff that oozes from pine tree wounds).

All fluxes should be removed from the board following the soldering process because resin is hydroscopic.Most manufacturers skip this critically important step to reduce costs. Billion falls into this category.

Once moisture enters flux, especially in high humidity conditions, resistance of the flux decreases. If flux islodged between circuit board components, you end up with a low resistance path where high resistance isneeded, in my case between the pins of the SDRAM chip on the Wireless Board. This was enough to stopthe Wireless Board from working. Of course, the time taken for the moisture to be absorbed coincides with 2days out of warranty. Talk about carefully planned obsolescence!!

Repair Procedure

1. Disconnect the machine from power.

2. Remove the 4 silicone rubber feet with a small flat blade screwdriver.

3. Remove the 4 Philips PCR screws.

4. Remove the lid.

5. Locate the Wireless Printed Circuit board which is the one piggybacked above the main boardand had the 3 coaxial cables feeding the 3 SMA Antenna Ports (See Figure1).

Figure 1

http://forums.whirlpool.net.au/archive/1593502http://forums.whirlpool.net.au/archive/1593502http://forums.whirlpool.net.au/archive/1593502http://forums.whirlpool.net.au/archive/1593502

8/9/2019 Billion Router Wi Fi Repair

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Created by Chris Humphris

Page 2 9/07/2012

Wireless Board Location

6. Inspect the board for signs of glue and flux on the pins of the SDRAM chip marked EM638165TS.Mine was very bad!! (See Figure 2).

Figure 2Flux not cleaned from chip during manufacture

7. Using a clean toothbrush and acetone or white spirits, carefully dissolve and remove all traces offlux from the pins of the chip. I use an old trick learned years ago of brushing with the solventand toothbrush, then quickly covering the wet area with a clean white cloth, and brushing again,pressing the cloth between the pins. This has the effect of soaking the dissolved flux into thecloth, evidenced by the appearance of brown stains on the cloth. Repeat the cleaning processuntil all traces of flux are removed. (See Figure 3).

Figure 3All flux removed

8. Inspect under a magnifying lamp or microscope and repeat Step 7 if necessary.

9. Ensure that all is clean and dry.

10. Apply power and the units Wireless section should come back to life as indicated by theillumination of the Wireless LED following Boot up. Worked for me.