Bosch SGS5312GB – electrical problem?

[andygod]

Our Bosch SGS5312GB died recently mid-cycle – no response of any kind. I checked the pcb and it had blown, so I sent it off to QER for repair. They have fixed it, but sent it back with a note saying they think the problem was caused by a fault in the machine rather than a power surge, and to check the electrics before replacing the board (presumably to prevent it blowing again immediately). They state the possible cause as ‘Poor neutral to pcb’.

Can anyone advise how best to do this? I have a multimeter.

Thanks

Andy

[Penguin45]

Re: Bosch SGS5312GB – electrical problem?

If your original board had actual “blown”, ie, tracks off the pcb, it’s unlikely to be a bad neutral, more likely a bad component.

In descending order of probability:

1/ Mains suppressor – look for sooty deposits around the unit.
2/ Heater.
3/ Soap dispenser solenoid.
4/ Motor/capcitor.

Your test meter may not be enough – ideally, all these components should be meggered for earth leakage. If you can track the loom back from the areas of damage on the pcb, you will have more chance of identifying the culprit.

For the benefit of future readers of this thread, stay safe – power off.

Penguin45.

[andygod]

Re: Bosch SGS5312GB – electrical problem?

Thanks Penguin

Part of the pcb looked burnt out, and there was soot on the inside of the case. The conductive coating on two of the connector tabs had disappeared (melted?). The wires from these two points connect to the dispenser actuator in the door, and the on/off switch. Does this mean the switch might be faulty?

Andy

[andygod]

Re: Bosch SGS5312GB – electrical problem?

Here’s a link to some photos of the burnt out board:

http://pbckt.com/sm.pnp

Tracing the wires back from the damaged area, they both point to the on/off switch. Is there some way I can test this to see whether it’s going to do it again? I don’t want to put the repaired board back in and have it blow straight away.

Thanks

Andy

[Penguin45]

Re: Bosch SGS5312GB – electrical problem?

Yup, that’s a blown pcb. I *think* that feeds the dispenser unit (No circuit diagrams unless you’re a BSH engineer 🙁 ). Use your test meter to follow the wiring loom – whatever is on the other end will have to be replaced as well.

Penguin45.

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