Psu directly turn on after plug cable to the wall (acbel e2470)

[Quaddro]

Hello..

I've got a old nice psu from my friend.
Acbel e2 power 470

But this psu rather weird, do something that i've never seen before.
This one automatically turn-on (without connect the green and black wire), after i plug the power cable to the wall.

Sooo.. there's no faulty in primary and secondary.. right?

For the first, i guess maybe faulty supervisor.
So i was replace the supervisor ic (wt7257) with the working one.

No good..

After i replace *ALL* the ic(s), transistors, 431, optocoupler, small caps near the supervisor ic, Even i was replace transformers (from working identical unit)..there's still same symptom.

Directly turn on after i plugged the power cable.
(diodes/ZD measured okay with multimeter)

* Primary uc3843 , tny277
* Secondary LM339, wt7257

I'm really lost here..
Any ideas?
Is the problem happened in primary or secondary side?

Thanks a lot.

[televizora]

Re: Psu directly turn on after plug cable to the wall (acbel e2470)

ATX power supplies are soft switched. They provide 5VSB to the mobo.
This powers some components, that allow the MB to wake up from events like network card or timer(BIOS setting to turn on the computer at specified time) or to be able to trigger PowerOn signal.
Usually the Mobo turns on the PSU by connecting Green wire to GND(black wire). Then it expects power good signal from the PSU to start the POST process.
You have MOSFETS, rectifier and control IC in the primary side.
Check if PowerON wire/Green/ is not shorted to the ground.
If not, check it's path to the control IC.
Also, this PSU is not nice, but almost trash. Even google barely knows it. Perhaps it is rebranded Codegen or something like this.

[Quaddro]

Re: Psu directly turn on after plug cable to the wall (acbel e2470)

You have MOSFETS, rectifier and control IC in the primary side.
Check if PowerON wire/Green/ is not shorted to the ground.
If not, check it's path to the control IC.

Yep, that's the first thing that i was check even before opening the box.
Black and green wire absolutely not shorted.

but, if psu turn automatically when plugged without connect green-black wire, i was notice there no PG signal.
But if i connect green and black wire, PG signal exist.

Also, this PSU is not nice, but almost trash. Even google barely knows it. Perhaps it is rebranded Codegen or something like this.

Actually this psu is pretty decent for office use.
Far from fireworks psu.
Acbel make their own psu, not from codegen or other else.