Neff U1721N2GB/01 Oven Blows Trip

[spanner51]

This built in oven blows the trip, but is very intermitant. I have meggered all the elements and they are OK. It only trips when customer is using the fan oven. There is a ceramic resistor in the top, next to a cut out, which seems to get hot, brings on the cut out, so that the cooling fan comes on.

Could this resistor short to earth when it gets hot?

Its all very frustrating when its so intermitant. Thanks

[Brains]

Re: Neff U1721N2GB/01 Oven Blows Trip

Have you meggered the fan motor?

Regards

[spanner51]

Re: Neff U1721N2GB/01 Oven Blows Trip

I meggered the oven from the terminal block and was getting just over 200M ohm

[Brains]

Re: Neff U1721N2GB/01 Oven Blows Trip

Was that with the selector in the fan oven position?

Regards

[spanner51]

Re: Neff U1721N2GB/01 Oven Blows Trip

Cant remember. I spent so long with my megger, it probably needs new batteries. I did notice the usual scorchy brown marks near the fan motor and cut out next to it, but as I said its very intermitant
Thanks for replying

[Brains]

Re: Neff U1721N2GB/01 Oven Blows Trip

I have changed a good number of fan motors over the years in Neff ovens. You may just have to take a ‘punt’ and see what happens. 😉

Regards

[spanner51]

Re: Neff U1721N2GB/01 Oven Blows Trip

I will.
Cheers

[Rograbbit]

Re: Neff U1721N2GB/01 Oven Blows Trip

Yes go for the fan motor. I had this problem a few months back, I think I posted something about it. Like you I was surprised as it’s not something fan motors normally do. Again I had good readings.

[spanner51]

Re: Neff U1721N2GB/01 Oven Blows Trip

Went back today and fitted a new fan motor, unfortunatly after 15 mins it took out the trip. (RCD) I reset it and the oven worked for another 10 mins before it tripped again. It meggers OK. I want to solve this puzzle before the customer gives up on a repair. Any thoughts please.

I am still tempted to change the ceramic resistor in the top. Thanks

[Brains]

Re: Neff U1721N2GB/01 Oven Blows Trip

Very strange.

Have you tried disconnecting the fan element completely and then run the oven? This would then eliminate the element failing when it is hot.

Did you carry out insulation testing with the selector in the fan oven position?

I suppose you have verified that the supply to the oven is okay (a missing neutral will trip the RCD)?

Have you checked the RCD with a RCD tester (just in case :twisted:)

I presume that you have ‘eyeballed’ the wiring to verify nothing is falling off or showing signs of breakdown.

Have you checked the grill element?

Have you checked the Function Switch & Selector Switch to make sure that nothing is breaking down to earth?

Starting to grab at straws now 😳

Can you get the oven back to your workshop & test there?

I’ll give this some more thought.

Let me know.

Regards

[eastlmark]

Re: Neff U1721N2GB/01 Oven Blows Trip

ceramic resistor is not likly to short to earth. How about that toc device next to the fan motor? and what about the cooling fan motor itself?

[spanner51]

Re: Neff U1721N2GB/01 Oven Blows Trip

I got so sick of messing about with this oven I just wacked in a new element ( the half moon one ), and………………… Job done, and it works OK. Up untill now that is

Thanks to all your comments

[Author]

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