Another Enermax not turning on (MODU 87+ EMG500AWT)

[Behemot]

One of many Enermax units which are not turning on and with which I had no luck so far. This time the fan does not even twist, I got absolutely nothing when grounding PWR_On. Which is OK at 3 V and stand-by has full stable 5 V.

It is resonant topology with CM6901. Found no shorted silicon, caps are all japanese. Soldering is quite messy but I checked few suspicious SMD components and they all seem OK. I am lost here…

[stj]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

caps may be japanese, but did you test the small ones related to the controller anyway?

[Behemot]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

Can do later but in all previous cases there was never a problem. Even with no-japanese caps there was never a problem.

Forgot to mention, monitor is Silicon Touch PS231.

[Ritchey1]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

Hello, I have another EMG500AWT for collaboration, sometimes it starts but more often it does not, same symptoms as above, going to write enermax about it. If they repair it or give some information how to fix it OK, but if not I swear I will never order enexmax again and will just buy SEASONIC as highend supplies.

[Behemot]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

I did not have time to work on that unfortunatelly…but I've been told problems are different each time, nothing is really common but the symptoms (which usually mean secondary monitor kicking in and turning the unit off).

[Ritchey1]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

Is it a good idea to try to convert such a non working enermax psu to bench power supply?

[Ritchey1]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

here are some pics to refresh this thread

[Behemot]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

I don't think you will succeed - because of the same reason we cannot reapir that. Too many protection and feedback circuits, it is too complicated. Also it is resonant unit so both sides heavily depend on each other for it to work, and it has limited window of parameters where it works OK so I think increasing voltage would not be possible much.

[Agent24]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

PS_ON should be 5v, no? 3v sounds low.

Where does PS_ON go into the PSU? Controller chip or what?

[Behemot]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

Don't think so, most modern PSUs I've measured (I don't do that usually) have 3 V. Basicaly it does not matter what the voltage is as long as it reacts for going to zero.

it goes as usually to the secondary monitor.

[Stefan Payne]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

Well, at least you can salvage the Case with modular PCB and use it with another PCB inside

You just need a fitting PCB and have fun...
Though it's not easy to desolder the cables on the PSU side...

[Agent24]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

Don't think so, most modern PSUs I've measured (I don't do that usually) have 3 V. Basicaly it does not matter what the voltage is as long as it reacts for going to zero.

I was just wondering if the 3v was indicative of a problem with whatever provides that signal, but maybe not, if other PSUs show the same thing. I looked at the datasheet and /PSON has a 30k/90k divider on that input, which would be 3.75v with a 5v Vcc, so I guess that makes sense.

it goes as usually to the secondary monitor.

To the PS231? Does it go anywhere else? PS231 seems to only supply PWR_GOOD and a fault detection outputs, I can't see how either of those would turn on the PSU, since I'd expect the PSU has to be running for those outputs to mean anything.

[Behemot]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

There is PSON pin, look again :P But yeah it always goes to driving circuitry as well which actually starts switching primary and pumping power to transformer.

[Agent24]

Re: Another Enermax not turning on (MODU 87+ EMG500AWT)

There is PSON pin, look again :P

I never said there wasn't one
They have the /PSON (pin 4) but it's an input with pullup, not an output.

But yeah it always goes to driving circuitry as well which actually starts switching primary and pumping power to transformer.

Probably the fault lies in the controller section, if it does absolutely nothing.

I would expect the thing to show some signs of life if the secondary monitor was bad, at least a fan twitch or something. The thing would have to start even a little bit for the protection circuit to realize there's something wrong and shut down.

Have you checked the obvious things, is the CM6901 getting power? Is pin 7 (CSS) above 1v? It looks like an enable input.
Have a look at the datasheet, it looks quite good, especially the example circuits.