Author Topic: Washing machine PCB - component replacement  (Read 430 times)

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Offline thyaguster

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Washing machine PCB - component replacement
« on: April 17, 2021, 11:21:16 pm »
So I had a problem on this board before, but with the help of fellow users got it working, it has been washing fine since then!

But this week a slug crawled on the PCB (yeah...) and both got toasted. I can see that R120 is dead but that's the easy part.
The slug was lodged near D15-D7, touching the transformer. I suspect the transformer died since it burned a hole on the PCB itself (only on one leg). I wanted to remove it to test and clean the PCB around that area but the transformer started to disintegrate as it was very brittle.

Now the thing is I don't know much about electronics, and when I search for the numbers on top of it I can't find anything. Can someone help me find a replacement?
Also, what should or could I also test along that area/circuitry?


Photos here: https://mega.nz/#F!cBUSQaLA!2bgk2_CZktFmOB6CbDKC2Q (these photos were taken before the first fix, so they have burnt components (triacs) that have been replaced)
 

Offline james_s

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Re: Washing machine PCB - component replacement
« Reply #1 on: April 18, 2021, 03:15:26 am »
What's that 8 pin IC next to the transformer? The transformer is probably a custom part, you won't be able to buy a replacement off the shelf. You may be able to repair it though, if you can find a datasheet for that IC which I suspect is the power supply controller it will probably have an example circuit similar to what is used there. It's also possible you could just add a separate external DC supply and disable the damaged one.
 

Offline thyaguster

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Re: Washing machine PCB - component replacement
« Reply #2 on: April 18, 2021, 08:35:46 pm »
It says "F BBHAC Q321", but I didn't find anything googling BBHAC.

I did find when searching for Q321
https://www.kynix.com/Detail/587684/Q321.html

This is FSQ321, seems to be the same, but can't be sure.
https://www.datasheets360.com/part/detail/fsq321/2739237769812975745/

Quoted myself from the old thread, since it was already identified.

 

Offline perieanuo

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Re: Washing machine PCB - component replacement
« Reply #3 on: April 19, 2021, 09:28:54 am »
So I had a problem on this board before, but with the help of fellow users got it working, it has been washing fine since then!

But this week a slug crawled on the PCB (yeah...) and both got toasted. I can see that R120 is dead but that's the easy part.
The slug was lodged near D15-D7, touching the transformer. I suspect the transformer died since it burned a hole on the PCB itself (only on one leg). I wanted to remove it to test and clean the PCB around that area but the transformer started to disintegrate as it was very brittle.

Now the thing is I don't know much about electronics, and when I search for the numbers on top of it I can't find anything. Can someone help me find a replacement?
Also, what should or could I also test along that area/circuitry?


Photos here: https://mega.nz/#F!cBUSQaLA!2bgk2_CZktFmOB6CbDKC2Q (these photos were taken before the first fix, so they have burnt components (triacs) that have been replaced)
hi,
first, i really don't see hole in smps transformer area, maybe you're mistaking the cuts that separate hot and cold areas
if the tnansformer is dead, you will never find him, if you are brave open it, undo the coils, note all like diameter and no of turns etcaetere, i mean make an identical transformer, but that's for the experienced people. maybe it's realistic to change the board or if you vahe space, put another supply with same voltage output levels ( maybe 2 voltages are made, but you can tell from filtering caps on smps transformer output).
I doubt he was gone, i'd guess control circuit or surrounding components are dead, but if his 'disintegrate ', no way of repair him, maybe find some other tranformer body same size and 'clone' the disintegrated one
but after remaking the transformer you still have to deal with control IC and around him
 

Offline fzabkar

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Re: Washing machine PCB - component replacement
« Reply #4 on: April 19, 2021, 06:47:29 pm »
It appears that FSQ321 is the correct part, although Google Images shows different variations of part markings, some with "Q321" on the top line, others on the bottom line.

Here is one that matches yours:

https://tecsho.com/Detail/ای-سی-ها-(IC)/168026/FSQ-321-DIP-8




https://www.mouser.com/ds/2/149/FSQ321-195587.pdf
 

Offline Alti

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Re: Washing machine PCB - component replacement
« Reply #5 on: April 19, 2021, 07:15:58 pm »
Check for opto-couplers on a PCB. If there aren't any then the only sensible way to turn on a triac in mains application is in QII and QIII by applying negative voltage. If that is the case then this burnt thing is a negative voltage offline switcher, non-isolated. So do not bother replacing it but simply add an AC/DC wallmart wall-wart (considering relay, looks like this is 9VDC powered).
« Last Edit: April 20, 2021, 08:12:41 am by Alti »
 

Offline james_s

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Re: Washing machine PCB - component replacement
« Reply #6 on: April 19, 2021, 11:25:28 pm »
Walmart? Did you mean wall wart? I would use one of the small potted power supply modules personally, not a wall wart. You'll want to make sure you remove enough parts of the original PSU to isolate it.
 
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