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Problem power supply Tech Star K3010D

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marketta49:
Hello everyone
I take advantage of my new subscription to your site to inform you that I have a problem with my 10Ampere Tech Star K3010D power supplying a LW-K305D-1 motherboard that is similar to the 5 Amp power supply K305D.
The problem with my Tech Star K3010D is that it stays fixed at 32Volt maximum and turning the non-adjusting pot always stays at 32Volt.
I ask you open that you are expert what can it be?
The components (ICs) are:
2X10N60C
1xMBR20200CTG
SG3525AP
LM324 8Pin
LM2904 8PIN
TNY280GN
Thanks to who solves the problem

marketta49:
I attach mother board photos

cat87:

--- Quote ---and turning the non-adjusting pot always stays at 32Volt.
--- End quote ---

Well, there's your first clue. Maybe you should try turning another pot that actually does something  :-DD

Sorry for the bad joke, I couldn't help myself.

Now, here's some actual advice:


--- Quote ---Thanks to who solves the problem
--- End quote ---
Sorry, but it doesn't work like that. Some people may come up with possible failure modes, then it's up to you to actually check if that is indeed the cause.

The "pot"... is it  an actual potentiometer or an encoder?
First thing, maybe the pot itself is dead. Try checking it to see, maybe the wiper got stuck on full tilt. Or if it's an encoder type. maybe something happened to the digital section reading it.

Because the unit is stuck on the maximum voltage, the first IC i'd suspect  is the SG3525. Either the feedback (resistor divider on the output maybe?) path is damaged  or the IC itself is bad.
Get the schematic for it and a scope and start checking it had the right signals on the pins.

Hope this help, but with the limited info you gave, that's about all I can come up with. A schematic attached to you post  might help :D

marketta49:
Hello
I thank you for the answer
you do not have to apologize, you have to always skimp, you're good at joking over it.
Then returning to repair and troubleshooting info you info that is a multi-turn potentiometer and I've got it and it's ok.
For the IC sg3525ap Pulse Width Modulator was my first thought and I replaced it but did not fix it.
Now my suspicion is that a port of the quad operating LM324 is broken
then I will try to verify.
I send the electrical diagram attached.
then let me know by looking at the scheme

marketta49:
I have attached the schema of k305d by 5Ampere, because it is the same as the schema change only the power FETs for the rest is the same

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