Enermax Liberty ELT500AWT fails to turn on

[PeteS in CA]

Re: Enermax Liberty ELT500AWT fails to turn on

yea just to clarify, i also have this unit and afaik, the liberty dxx series seem to use some kind of a relay for the automatic ac voltage detection or sumthing. so when powered on, the unit will make a clack, crack or tick sound when powering up. this is normal. the superflower leadex series also uses a relay and makes a similar sound when powering up.

Many PSUs used in desktops use a switch to set it up for 115VAC or 240VAC. This switch can be replace with a (safety agency rated) relay, driven by a circuit that senses the input voltage and sets the relay accordingly. A nice feature, especially in 240VAC countries where forgetting to set the switch to 240VAC results in a loud noise and a dead PSU.

Another use of a relay that I've seen is to short out the inrush limiting thermistors after the PSU has been on for a few 10s or 100s of milliseconds. This allows use of higher cold resistance thermistors that are not hugenormous.

[kc8adu]

Re: Enermax Liberty ELT500AWT fails to turn on

you are hearing a soft start relay.
i have an antec 750 with one.
i add them to big hf amps to prevent killing the now unobtainium power switches from inrush.
even more important now that much larger,lower esr caps were used in the plate supply rebuilds.
i use an icl rather than a resistor.the relay bypasses it ensuring if the power flicks for whatever reason it will be ready again.

[vwtcxqdh]

Re: Enermax Liberty ELT500AWT fails to turn on

Have someone find out what capacitor makes is the typical one that makes this does-not-power-on problems? I understand that i makes sense to replace all caps after that many years but because the PSU works fine when it turns on once, it would make more sense to me to just replace this one or two caps that make those power-on problems.
Seems like the whole fist enermax liberty series have exactly this one power-on problem after time.

[pdavid]

Re: Enermax Liberty ELT500AWT fails to turn on

Good day all.

This week while using my workshop computer, I had a BSOD and the computer restarted, it got into windows and the computer locked up, So I then pressed and held in the power button.

Since then I have not been able to get this PSU to turn back on again.

When the mains power is on, I get the 5volt standby fine, but you press the power button you hear a click, and then a high pitch wissle/buzzing.

The power supply in question is a Enermax Liberty ELT500AWT.

I have removed the lid/cover, and I can not see any burnt/damged parts.

I have read that some early Enermax psu's had glue that would short out, but this psu does not look like it has any of this glue near the high voltage parts.

I haved tried this power supply in a computer, and on the test bench, but it still fails to switch on.

When I get some free time I am going to strip this psu down more, and go hunting for the problem.

I have now ordered a new psu to replace this one with, but I would like to try and find out what had failed in this psu.

Can anyone please give me some pointers on where to look?

Best Regards.

I had two of these units with the symptom you described! Turned out to be a shorted npn smd transistor on the secondary. I don't remember it's location... but it had 6F marking on it. I hope this helps.

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

Yeah but it could be random SMD diode, transistor, capacitor - can you test all of them?