Bosch Dishwasher Soap Dispenser Fault

[karlosatyeovs]

I have a Bosch SGS5342GB/17 HydroSensor dishwasher where the soap dispenser is failing to open during the wash cycles. I have checked the actuator arm (moves ok when manually operated) and the dispenser door itself. I have also removed the wax motor and this operates OK when 240V is put across the terminals and it also measures ~2150 Ohms on a multimeter. Therefore I am thinking that the feed to the wax motor is duff which points to the control board. If this is the case then it may be that the Triac that supplies the wax motor needs replacing. Anyone able to confirm that this is likely to be the case? I would rather try replacing a single triac for pence than replace the control board at nigh on £100+. If so, has anyone done this and with pictures or hints?

I realise that I could just bung the soap tablet straight into the machine but I like things to work as designed hence my desire to attempt a fix. If it turns out to be uneconomical then I will revert to soap loose in the machine.

Thanks in advance

[Martin]

Re: Bosch Dishwasher Soap Dispenser Fault

I suspect that at this stage you haven’t actually checked the triac? Usually it will shows signs of damage (i e. Its top blown off!).

[karlosatyeovs]

Re: Bosch Dishwasher Soap Dispenser Fault

Martin,
You’re correct, I havent yet had the control board out to check, that is my next job for this weekend! As you say the damage may be obvious when I do get it out. Do you know if the triacs are the ones that have a D cross section (like a transistor) when viewed from above or if they are ones that can be mounted to a heat sink (with a metal tab attached). Thanks for your reply

[Martin]

Re: Bosch Dishwasher Soap Dispenser Fault

D cross section type I believe.

[karlosatyeovs]

Re: Bosch Dishwasher Soap Dispenser Fault

If anybody else suffers this problem and it turns out to be the control module then I have uploaded a photo of the failure mode of the triac in question. As Martin posted in his reply, it was quite obvious which triac had failed as it had indeed blown the top off! See photo with failed TRIAC circled. If you zoom in you can just see the crater in the triac (quality not great but you get the idea of component location and failure)

The triac is an SMD triac part number Z0109MN (=Z9M) and can be bought for pence from many electronics suppliers. I will have a go at fixing the board over this weekend and report back on the success or otherwise.

[karlosatyeovs]

Re: Bosch Dishwasher Soap Dispenser Fault

I got the replacement triac and carefully unsoldered the failed one (using low melt solder) then soldered the replacement and refitted the module. Waited while the wash was progressing and at 75 mins indicated on a normal wash cycle the wax motor activated the dispenser arm. Success! Very happy to have it all working as advertised and only for a couple of quid not the £100 to replace the whole module. :tup:

[Author]

Posts