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I have replaced the control board on my Bosch WFG2420GB/01 which has solved the problem of the machine failing to start. But now although it appears to run through the programme it fails to turn. All the connections to the replacement board seem sound. There is a clearly visible blackened area on the board that came out so I’m wondering whether something motor-related could have blown up a component on the board.
Would changing the brushes be likely to fix the problem or does the blown component suggest something more serious? How best to diagnose what’s actually been going on?
Re: Control board changed but machine not turning (Bosch)
andykent wrote:How best to diagnose what’s actually been going on?
Firstly THE most obvious thing to check is the motor. 😉
The motor is the component that takes all the stress and strain and the most likely of all parts to fail.Brushes wearing a common problem. You will also need to clean away all signs of carbon dust from the motor and dismantling it completely is favourite for that. But first, check all the terminals for electrical continuity ( i.e. Pin to pin). That’s a dead giveaway toward problems within. Before refitting check the earth potential of each terminal. Any leak to earth will cause electronic issues with the main board or worse still keep tripping the RCD.
Have fun! 🙂
Re: Control board changed but machine not turning (Bosch)
Thanks for your quick response.
So now I have the motor sitting on my table. The brushes are indeed pretty low even though replaced them 2 or 3 years ago. Are budget ones (which they were) so inferior to genuine ones?
If the problem is anything other than brushes or cleaning is it bye-bye motor?
We did in fact have some RCD trips just before the machine failed, which I thought at the time were due to another toaster or kettle end-of-lifeing.
Not sure what you mean by ‘pin to pin’, can you spell it out for the hard of thinking 🙂
Re: Control board changed but machine not turning (Bosch)
andykent wrote:Not sure what you mean by ‘pin to pin’, can you spell it out for the hard of thinking 🙂
You should have continuity between two or more pins (motor terminal connections).
Re: Control board changed but machine not turning (Bosch)
So, the motor looks in pretty good nick inside, bit of carbon dust (duly wiped) but not too much, commutator not too worn, windings sound, no signs of overheating, didn’t detect any earth leakage.
But I’m surprised how quickly my replacement brushes wore out – 2/3 years when the originals lasted 15. How would this happen? And would it be sufficient to have blown the main board?
Re: Control board changed but machine not turning (Bosch)
andykent wrote:But I’m surprised how quickly my replacement brushes wore out – 2/3 years when the originals lasted 15. How would this happen? And would it be sufficient to have blown the main board?
Firstly, yes pattern brushes are inferior to the genuine ones. They are marginally softer, wear down more easily and hence give off far more dust. However, whether you fit pattern or genuine brushes the commutator segments over 15 yrs use wear significantly. Often as not requiring rebedding with a ‘commutator stick’ to remove the groove and make each segment smooth across its entire width.
As for blowing the main board then that is very unlikely as the integral thermal trip would stop that from happening and, in most instances, the house RCD/MCB would trip anyway. That’s not to say the motor wouldn’t but it would be a rare event if it did.
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