Blown oven

Hi all. Having a problem with my double oven. I turned it on today, (it was already on as in the clock was displayed, but as I turned the knob for the oven to come on) there was a spark and killed the fuse and RCD. Turning it all back on proved the oven as dead. Power is getting into the back and up to the main PCB as pictured below.


I have removed the PCB and found scorch marks where something has blown and taken out some other bits. I do know a little bit about electronics and know my way around a soldering iron but only basic need-to-know stuff so was hoping for some help from the experts as I am hoping it is something I can just order online and solder on to replace.

I have attached a photo of the PCB with the issues that I can see (not saying that there isn't more). I have put my multimeter across some of the damaged parts and have tagged the results.


1. I know this is a transistor and it has a pin come off the board and will need replacing. Are these all the same or will it be specific?


2. From searching the S10K275 number printed on it this is a Varistor. This has a long blown from the board.


3. I assume a capacitor of some sort from the 'C' number printed on the PCB next to it. The left and middle one show some resistance when MM put on 2M but the right one doesn't read anything.


4. Jumper wire also blown. Can I replace this with a normal piece of wire or does it have to be something specific?


My questions are, can anyone tell me where they think the problem might have originated? Does the above sound right? If I manage to find and replace the above parts, is it likely to work or do you think these would have blown due to a different problem somewhere else?


Oh, not sure if its worth mentioning, but I took the lamp in the oven out and it has blown. I thought it be a little much if the lamp blew and took out the PCB but I dunno??


Thank you all in advance, any advice or help needed.




Steve

I have just noticed something. On the underside, the pins labeled L3 go to the JP wire thats blown. It then splits off to the blown Varistor, then to the yellow transformer looking thing behind it.

1. Is that a transformer?
2. Is there a way of testing this whilst powered down for faults with a MM?
3. Could it be the yellow thing that has caused the problem and just a few little components?

That is a catastrophic failure. If the wires blew off this side of the board, what to the copper traces look like on the other side of the board?

I am guessing the transformer failed and sent 230vAC to the low voltage control parts you've shown. See the ripples in the yellow film covering the transformer ? (Edit - I didn't see your follow up post - yes the yellow brick is a transformer. )

Welcome to ETO.
Oven make/model?

alec_t said:

Welcome to ETO.
Oven make/model?

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Oh yes sorry, its a Whirlpool Type: FXTM9, Model: AKZ161/03/IX, barcode: 858516115124

gophert said:

That is a catastrophic failure. If the wires blew off this side of the board, what to the copper traces look like on the other side of the board?

I am guessing the transformer failed and sent 230vAC to the low voltage control parts you've shown. See the ripples in the yellow film covering the transformer ? (Edit - I didn't see your follow up post - yes the yellow brick is a transformer. )

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Thanks for your reply.

To be fair I think the tracks look ok... (attached photo)

Is there anyway of testing the tranny? Like continuity across specific pins? And if so, would you know what pins? There is 8 pins labeled 1-8.

Just found a replacement board for £100. I know its not much, but wondered what the chances are of getting the components and doing it myself. Attached a photo of the board I found zoomed in on the transformer for ID. Whats the chances of finding one of these do you think?

gophert said:

That is a catastrophic failure. If the wires blew off this side of the board, what to the copper traces look like on the other side of the board?

I am guessing the transformer failed and sent 230vAC to the low voltage control parts you've shown. See the ripples in the yellow film covering the transformer ? (Edit - I didn't see your follow up post - yes the yellow brick is a transformer. )

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So I refitted the board, wired it up and turned it on and took some readings. The JP jumper wire that broke (number4 on pic) was live with 240V. It appears that is the main feed into the transformer with the primary being on the right side of the pic and the two secondaries on the left. I measured all across the transformer with nothing on any pin. To me (and I may be wrong, in fact I usually am) that the components have blown 'on the way' to the primary.... If the tranny had gone open wouldn't it have killed the components after the secondary outputs which are low voltage? Could it just be that something had blown on the way into the trans? Ie part 1,2 3 or 4 which then took the rest out?

stevelondon2021 said:

Thanks for your reply.

To be fair I think the tracks look ok... (attached photo)

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The track is blown at the top middle.

stevelondon2021 said:

Just found a replacement board for £100. I know its not much, but wondered what the chances are of getting the components and doing it myself. Attached a photo of the board I found zoomed in on the transformer for ID. Whats the chances of finding one of these do you think?

View attachment 129643

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That looks like an entirely different (and MUCH older) board.

You won't be able to source parts for the board, because it's a custom board with a custom switch-mode transformer, the service procedure is to replace the entire board.

Nigel Goodwin said:

That looks like an entirely different (and MUCH older) board.

You won't be able to source parts for the board, because it's a custom board with a custom switch-mode transformer, the service procedure is to replace the entire board.

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FFS. lol. I love fixing things so thats pi$$ed me off. Oh well, in the bin it goes. Its not worth paying £100 to replace the board on a 13 year old oven when you can buy a new one for £350.

Thanks anyway.

I think it is very unlikely the transformer caused the tracks an wire to blow. You will need to trace out the schematic of the power side of the board. That is the paths that that come from live and neutral into the board via contacts on relays (Which I assume) will be on the board. I think the most likely cause of the fault is a short that has developed in one of the heating elements or damaged insulation on some wiring. It is just possible that that when the bulb failed it could have arced between the wires supporting the filament. Tracing the part schematic of the board and the wiring in the oven should help you to narrow down the cause. I think if you just replaced the board without doing a proper diagnosis of the fault you would just destroy the new board.

Les.

stevelondon2021 said:

FFS. lol. I love fixing things so thats pi$$ed me off. Oh well, in the bin it goes. Its not worth paying £100 to replace the board on a 13 year old oven when you can buy a new one for £350.

Thanks anyway.

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That's the price you pay for low cost products - service and spares supply costs MONEY - the give away prices means there's no money there to fund it.