Samsung SMPS

[Burned]

Re: Samsung SMPS

Looks like the schematic might not match the power supply in that unit.
Do you have + and - 12 volts on con4 ?

Yes I do. That is coming from the other transformer (T2)

If you measure 332v on Qa1 drain, it looks like the circuit is working??? and you should have +/- 40

It should, that was replaced (QA1) as well as CA8 and FL1.
But still no +/- 40 out of that transformer (T1)

Check the voltages on ic5 (ic3 on schematic) That looks like some kind of protection circuit.
I still think there could be a fault with the audio outputs and the +/- 40 is in protection.

I have nothing at IC5 for voltages

[Burned]

Re: Samsung SMPS

1) Measure the resistance between GND pin and +43V pin.
2) Measure the resistance between GND pin and -43V pin.
3) Measure the resistance between -43V pin and +43V pin.
Report the readings.

1)10M ohms
2)6M ohms
3)6M ohms

[R_J]

Re: Samsung SMPS

What resistance do you get if you check each speaker output terminal, they should be around 10K
ICA1 can't be working, it needs more than a couple volts on vcc to work. If QA1 was shorted, it may have damaged the ic. If the fet was shorted drain to gate, that would put 160 volts on the ic's output pin, which is usually not good.

[Burned]

Re: Samsung SMPS

I get 2K Ohms at the outputs

I placed an order for that IC ICE2QS03G.

[Burned]

Re: Samsung SMPS

I have replaced QA1 and it now outputs 11 volts at VCC.
The unit turns on and stays on!! No more protection mode.

It looks like it is fixed.

Thank you for the help!

[vinceroger69]

Re: Samsung SMPS

Thanks for the update.