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– Oven blew MCB & ELCB, then played ‘dead’.
– Given age (9.5 years) replaced HV Capacitor and HV diodes.
– Unit powers up displays for 5-10 seconds, then went out (nothing else worked).
– Replaced duff 7812 voltage regulator; repaired burned out PCB track to K9 relay [thermoactuator, which was O.K., and PCB connector 28]. Also (precautionary) replaced diode bridge (4 x 1N4007 + 1 x 1N4007) and 2 x 2200 uF smoothing capacitors on PCB. This got display panels working O.K., timers count down O.K. but no relays are switched on PCB, so nothing (lights, fans, oven elements or microwave circuit) works.
– Replaced 7805 regulator and checked that +5V correctly gets to upper and lower display/controller PCBs from main PCB. Still nothing else but the displays.Is there a ‘reset code’ (push a strange combination of buttons, as with some other white goods) to get the unit to come back on again? Or any ideas on what to look at next?
Appreciate any input!Re: NEFF H7871NOGB/03 Combination microwave oven reset code?
I have had two of these lately, Neff and the similar Bosch version.
On both of them it was the chip on the lower display panel knackered from the flashover so had to replace both the display module and power module on each. Very expensive!Re: NEFF H7871NOGB/03 Combination microwave oven reset code?
Thanks MicroGerry for information – helped in the final diagnosis! Fixed it by replacing lower display/control module (£196!), as suggested, and replacing all (yes, ALL) transistors on the Power Control Module – a couple of £ compared to £123 for replacement PCM. I conclude that, when the track vapourised, it momentarily put 240V on the 12V rail, which promptly took out the (normally indestructable) 12V regulator and all the transistors. For those who haven’t hit this problem yet I would recommend plastic sheet between the two pcbs – should stop this problem, if it occurs, from destroying that really expensive lower D&C module.
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