Flasher/Warnings CPU

[Casey]

I brought my ecu to Castle Combe last weekend to give to you for testings but forgot and left it in the car all weekend!

Ship it to me if you like?

[Casey]

Update. Both of gt_james' CPU's are now fully functional

The "rusty backplate" unit needed the suspect capacitor replaced to repair the ignition barrel lamp timer function, and both units needed the connectors cleaned up. I also removed a lot of (35+ year old) excess solder flux from the "rusty backplate" board, as it could lead to corrosion or bridging of PCB tracks.

The "rusty backplate" unit also had a PCB track missing, so bridged it and glued the bridging wire in position. Note the semi-circle of track missing!

I've now moved on to another voyage of mystery black box discovery ... viewtopic.php?f=22&t=4786

20220723_131505.jpg (138.88 KiB) Viewed 12297 times

20220723_132845.jpg (182.4 KiB) Viewed 12297 times

[gt_james]

Nice work!

I have that indicator flasher here by the way, but keep forgetting to get it in the post to you

[ian65]

Great work,

I need to post my module down to you

[Hobbawobba]

I brought my ecu to Castle Combe last weekend to give to you for testings but forgot and left it in the car all weekend!

Hahahahahaahahaha always the case aye bro!

[Casey]

I have had another unit sent to me by a member on here for checking. My tester confirmed the flasher function has failed, which aligned the owner's reported problem with the unit. All other functions are OK.

I've got as far as dismantling the unit to visually inspect the board and circuitry associated with the flasher and can't see any obvious visual failure. Instinct tells me one of the 2 transistors has failed - the capacitors showing no sign of leakage or gassing. I need to do some further tests with my oscilloscope to confirm diagnosis.

CPU Flasher 1.jpg (74.9 KiB) Viewed 12213 times

[Casey]

I have now fixed the current CPU with a flasher fault. A weird one. Apart from a dodgy looking dry joint to one the connector pins and a strange looking solder blob on another, all looked visually OK.

Note the cracking around the solder pad joint, top-centre, and the rather awful "blob" of solder on the pad just below. Both connect to the wiring loom and are associated with the flasher operation.

20220923_161246.jpg (133.85 KiB) Viewed 12183 times

On testing the circuit, all looked good and every component checked out, but the indicator lamps on the tester were not operating. The circuit does rely on the lamp load to function, the current draw operating a reed relay switch which then starts a delay which creates the indicator timing.

After some further testing I realised that the pin on the PCB side of the board (under that horrible blob) which goes through the board to the connector blade to supply the indicator lamps was open circuit! There was a break between the back and front of the board - very unusual.

Here is the connector blade removed - in TWO pieces, no wonder there was an open circuit, it has corroded through, probably accelerated by the high current flow to two indicator lights (or four, if hazards are on). This fits exactly with the owner's report that the indicators starting working intermittently, before failing completely. The quality of the gold plating leaves something to be desired too!

20220923_174702.jpg (90.12 KiB) Viewed 12183 times

Repair involved soldering a copper leg to the connector blade and shaping it a bit with a Dremel to fit the connector housing. Ignore the 50mmx300mm on the workstation mat!

20220923_175108.jpg (117.53 KiB) Viewed 12183 times

Some opening up of the connector housing was required to get a good fit, this was then back-filled with epoxy resin

20220923_190548.jpg (96 KiB) Viewed 12183 times

Next, solder the new the copper leg to the PCB pad and re-flow the dodgy joints around it with fresh solder and flux.

20220923_191708.jpg (150.24 KiB) Viewed 12183 times

Flash/indicator function now works flawlessly

[Casey]

The owner of the above CPU has now received the repaired unit and has confirmed all is working as it should

Great to be able to get another of these units working and back in service.