2 SAMSUNG washing machine doesn't power up
I have a washing machine that has stopped in the middle of a cycle and showed an 'UC' error. On the SAMSUNG's site it says that is is related to the excessive fluctuation of the power supply voltage. I turned it off and now it doesn't turn on anymore.
Analyzing the main board, I've checked low voltage power supply and it seems to work, it outputs 37V (or something like that, I don't remember the exact value). On some connectors I've measured 5V and 12V.
In the same board there is also a relay connected to the input that, when active, powers other components (like the door lock) and the main rectifier circuit that powers the inverter.
If I bypass that, the machine turns on and after a couple of seconds I can hear the relay activating. At this point I can remove the bypass and the machine stays on. (I haven't tried to run a cycle)
At this point I'm not sure on what is the problem. The description of the error code makes me think that it has something that measures some kind of voltage? (I don't know what it checks and where), so maybe that is faulty? Or I'm missing something else?
I've attached a simplified schematic that I've drawn while trying to understand how it works.
Moreover, I've found a service manual online that have some details on the wirings: https://www.manualslib.com/manual/279727...
Do you have any suggestions? Thanks.
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3 comentários
@dennisloi what model is your washer?
por oldturkey03
@dennisloi Can you upload pictures of the circuit boards inside your washing machine?
por Andrew S
@oldturkey03
@andrewsawesome
Sadly I don't have anymore access to the machine or the board, so for now is on "standby".
Anyway, the internal board is exactly the same as the service manual that I've linked.
I don't have any pictures of the board because they are covered in resin and is very difficult to take a good photo. But nothing seems blown or burned on the board.
I have done some more troubleshooting after the post, here's what I have found:
- I traced the power supply for the relay, the rail is not active because the enable pin of the regulator is off (my guess is that it's controlled by the microcontroller)
- There is a optocoupler that sense the AC voltage, the LED seems fine (I've measured a voltage drop of 1.3V), but I'm not sure about the output as was still covered in resin.
Anyway, I will update this post (or put a comment) when and if I will be able to continue working on it.
por Dennis Loi