Bosch Condensing Tumble Dryer (WTE69) - won't start

[ljandal]

Hi there,
I'd really appreciate your help with this as I am all out of ideas.

The tumble dryer turns on fine, LEDs light up, you can set any program you want, cool or hot but when you press start nothing mechanical happens. But no drum turning and no heat.

I've tested the following
Door switch - must be ok otherwise wouldn't be able to press start
Drive belt is fine (as is smaller belt between motor and gear)
Condensing chamber is empty of water
Sump is clean
Pipes are clear (blown through them)
Pump and float switch near sump seem fine. No open circuits
Front thermostat on drum exhaust vent seems fine, closed circuit
Rear thermostat on heater seems fine, closed circuit
Electrical cut-out may be a bit suspect, not sure what resistance readings I should be getting here
Heater element seems ok, returns resistance of 20-40 Ohms, can't remember exactly how many now but I think it was within that range.
I think the capacitor is ok. I don't have a capacitance tester but have tested resistance and on the 2MOhm scale is starts at 0 and rapidly climbs to overload, or does that indicate an open circuit?
(Can't get the drum turning on its own with a push - there doesn't seem to be any power to the motor.)

So what do I test/replace next? Happy to retest anything mentioned above too. Is it the thermal cut-out, capacitor or something else. Any ideas?!

I'm not sure how old the machine is but having worked on it, it seems fine mechanically so I'd really like to repair it if the parts are ok price-wise, unless people think it's best to scrap it?!

Model number is (E-Nr) WTE6920GB/04
FD 8403 200099

Would really appreciate your help with this and many thanks in advance for your kind assistance.

Thanks
John

 

[DJB2]

Cut out stat should read 0 ohms and if tripped will be open circuit. In our machine, the dryer will still start if stat has tripped but has no heat. You could try temporarily shorting the stat to see if motor will start. Otherwise fault most likely to be door interlock or motor fault.

 

[fidom]

It could be the start relay on the PCB. You would normally hear a small click from the relay when you press the start button.

http://www.bosch-home.co.uk/store/spareparts/CONDENSATIONDRYER/WTE6920GB/04

 

[ljandal]

Thanks to DJB2 and fidom for the helpful replies.
It's taken me a while to get back to this as we had a hive of bees in the chimney which we needed to get rid of.

I went back over the tumble dryer checking out the suggested causes. In the end I put lots of WD40 in the door catch, slammed the door a few times and voila it works so it must have been the door switch after all that.
Also replaced the bulb, which had blown, so she's better than new.

Thanks to you both for your help.

John