[Oldrepairer]

Oldrepairer wrote:This is an old cooker, probably about 1990 but is still worth repairing if possible.
The power relay on the small PCB (EC133B , 13-670L) has suddenly started to emit quite a loud vibrating noise. This occurs whenever power is applied by the rotating controls to any of the heaters eg ovens or grill. As it appeared to be a problem common to power application, as a first possibility I replaced the power relay LZ 24S.
Sadly, still noisy.
I have the problem that I cannot get a circuit diagram or block schematic for such an old cooker so diagnosis is difficult.

Has anybody thoughts on what could be the problem?

An update.
I managed to obtain a used PCB and replaced the original. Problem solved. Almost certainly the problem was a failing diode on the original PCB. When tested in the positive direction, it conducted for a split second and then went open circuit ( or very high resistance) I can only assume that this was happening repetitively causing the power relay to chatter. – good for another 30 years!

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