Enermax EG365P-VE 350W mystery...
My friend passed this PSU to me since it was already out of warranty and faulty. Its a "+12V enchanced" version with 26A on the +12V rail (which should qualify it as 400W by newer ATX standards).
On my first examination, all voltages (+5V, +12V, +3.3V, -5V and -12V)are fine and within tolerance but I've noticed the PWR_OK signal was low (around 0.23V only) and so I thought it was the LM339N I.C faulty. I replaced that I.C thinking it would solve the problem but it didn't (PWR_OK line is still low)! It could power up but I have to manually power off thru the power switch at the back of the PSU. No response from my test system at all while the power was running (ie. blank screen)..
Next I decided on the cost cutting "trick" that generic PSUs use, just pull that PWR_OK high (usually via a resistor pull up). I noticed there was a 1K pullup resistor thus I just made a fine cut on the PCB track to disconnect the output from LM339 pins, thus forcing the PWR_OK high all the time. The test system could power up, and can now power down as well thru the soft PWR on button. But still no response from my test system at all while the power was running (ie. blank screen)..
I'm at a lost here... All voltages as measured thru my digital multimeter are rock steady and within tolerance (readings +4.97V, +12.09V, +3.36V, -4.94V and -11.77V). Is it possible that the rails have so much ripple (not picked up on my multimeter) that the system wouldn't be able to function?
Anyway, the capacitors in this unit seems to be no name (I see "VENT" that's all). Will recapping ALL the capacitors revive this PSU? There's many of them (on the output side) and pretty "crowded"...
Also should I invest on an oscilloscope? I'm not doing this full time (no, my full time job is not repairing equipment)
On my first examination, all voltages (+5V, +12V, +3.3V, -5V and -12V)are fine and within tolerance but I've noticed the PWR_OK signal was low (around 0.23V only) and so I thought it was the LM339N I.C faulty. I replaced that I.C thinking it would solve the problem but it didn't (PWR_OK line is still low)! It could power up but I have to manually power off thru the power switch at the back of the PSU. No response from my test system at all while the power was running (ie. blank screen)..
Next I decided on the cost cutting "trick" that generic PSUs use, just pull that PWR_OK high (usually via a resistor pull up). I noticed there was a 1K pullup resistor thus I just made a fine cut on the PCB track to disconnect the output from LM339 pins, thus forcing the PWR_OK high all the time. The test system could power up, and can now power down as well thru the soft PWR on button. But still no response from my test system at all while the power was running (ie. blank screen)..
I'm at a lost here... All voltages as measured thru my digital multimeter are rock steady and within tolerance (readings +4.97V, +12.09V, +3.36V, -4.94V and -11.77V). Is it possible that the rails have so much ripple (not picked up on my multimeter) that the system wouldn't be able to function?
Anyway, the capacitors in this unit seems to be no name (I see "VENT" that's all). Will recapping ALL the capacitors revive this PSU? There's many of them (on the output side) and pretty "crowded"...
Also should I invest on an oscilloscope? I'm not doing this full time (no, my full time job is not repairing equipment)
Well, that's where this Enermax Liberty ECO 400 Watt PSU came from. Like I mentioned, it had cut cables and many bulged caps on the DC output side. I stripped a few cables and did a quick temporary recap with whatever junk (but still reading OK) caps I could find, then performed a basic power test – the PSU passed. 
Thus, I knew I'd eventually go around to repairing it. One year later and we're here. 
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