My boiler had divertor valve problem in past, plumber replaced it for a reconditioned one-it lasted about 2 months. The hot water was ok when heating was on. I decided to live with this.
Several months on the boiler has stopped working, the red light at the top is on and the yellow CH demand is glowing. On the main control board there is only 23Vac instead of 240Vac according to the service manual, and it suggests the main circuit board is to be replaced. Disconecting the NTC temp sensor and restarting the boiler made no difference.
All fuses are ok. I am an electrician so I will do it myself, before I replace it is there anything else I should check.
If it is the circuit board is there a known component that can be changed/tried. The fan appears to be powered by a relay whose coil resistance seems ok. No burnt components visible.

CK, January 2008

you should leave it alone and call a CORGI reg. repairer, changing the circuit board may be correct diagnosis but it should also. be correctly serviced. you may be an electritian but how do you feel when someone tries to do your job and bodgers it then makes matters worse

wally, February 2008

Just adding clarity to my question above, the pump does work, the 24Vac is on the Fan connector instead of 240Vac.

ck, January 2008