Enermax Liberty ELT500AWT fails to turn on

[Mad Professor]

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.

[ben7]

Re: Enermax Liberty ELT500AWT fails to turn on

maybe shorted capacitor, or a shorted output rectifier.

-Ben

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

First, try to turn the PSU on just without any load (that means with all the power connectors unpluged from components in PC). Do it by shorting the green wire to the ground.

It may actually be there is something shorted in the PC itself what prevents the PSU from starting due to short protections.

[retiredcaps]

Re: Enermax Liberty ELT500AWT fails to turn on

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.

This could be a bad small capacitor. They don't have to bloat to be bad.

My friend had an Antec SP350 that whined and it was a bad 22uF 50V cap on the hot side if I remember correctly.

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

There are CEC caps, at least the bigger ones in these PSU. They should be somehow decent. However, I don't remember the smalls, they may be CapXons or something, which are basicly on sight replacement for me and even it does not happen so often people say, they may fail.

[dmill89]

Re: Enermax Liberty ELT500AWT fails to turn on

There are CEC caps, at least the bigger ones in these PSU. They should be somehow decent. However, I don't remember the smalls, they may be CapXons or something, which are basically on sight replacement for me and even it does not happen so often people say, they may fail.

The last enermax of that vintage (Nosietaker 600w)I recapped was 100% CEC except for the two 680uf 200v Panasonics on the primary. It had a failed cap on the 5VSB rail. I ended up replacing all the caps except for the Panasonics due to the age and fact that CEC's are mediocre but not great.

The newer enermax's seem to use mostly NCC caps on the secondary and still use Panasonics for the main filters on the primary.

First, try to turn the PSU on just without any load (that means with all the power connectors unplugged from components in PC). Do it by shorting the green wire to the ground.

It may actually be there is something shorted in the PC itself what prevents the PSU from starting due to short protections.

I'll second that, If it still fails to run follow the suggestions below.

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

The CAPs would of course be a good place to start, Be aware that some of them (the ones near the heatsink) may be sleeved in heatshrink tubing to insulate them (Based on internal pics of the Liberty 620w) and this may cover up any bulging/venting.
Of course do a close visual inspection of all components on both sides of the PCB for any damage.

If nothing is found you'll need to pull out a DMM and start checking components, primary switchers, and output rectifiers would generally be the first thing to check if no other components are obviously failed (although If the primary switchers were bad I would not expect it to even attempt to turn on so fucus on the output rectifiers first).

If nothing is noted you'll need to start checking the more minor components and possibly ICs. Honestly given the price of a 500w PSU these days (<$60) I would probably stop and scrap the unit if it reached this point since it could take a massive amount of time to find the culprit if it is a minor component or failed IC without any visual damage.

[Mad Professor]

Re: Enermax Liberty ELT500AWT fails to turn on

I did say in my 1st post that I did test the power supply on the bench, but I guess that was no very clear to if I still had the PC connected or unconnected.

So with the PSU not connected to anything bar the mains power, when you ground the green wire, the power supply makes a single click, and no other noises, and the fan does not spin.

Doing the same test on the bench again with a old spare and known working motherboard you press the power button, there is that click again, followed by a high pitch buzz/whisle sound, I seem to be the only one that can hear the sounds.

As for the caps, non look like thay have poped, but you never know if it's bad unto removed.

Pri side there is one big cap, Rubycom 330uf 400v.

Sec side there are alot of caps, but mostly seem to be the following.
CTC 1500uf 10v.
CTC 3300uf 16v.
JP 1000uf 10v.
JP 3300uf 10v.

There are alot of small caps doted around the pcb.

[dmill89]

Re: Enermax Liberty ELT500AWT fails to turn on

I did say in my 1st post that I did test the power supply on the bench, but I guess that was no very clear to if I still had the PC connected or unconnected.

So with the PSU not connected to anything bar the mains power, when you ground the green wire, the power supply makes a single click, and no other noises, and the fan does not spin.

Doing the same test on the bench again with a old spare and known working motherboard you press the power button, there is that click again, followed by a high pitch buzz/whisle sound, I seem to be the only one that can hear the sounds.

I would definitely take a look at all the switchers and rectifiers on the secondary. A cap is possible but if none are visibly failed I would expect it to at least try to turn on or come on with one rail bad or lots of ripple. Those symptoms seem more indicative of bad silicon switchers, rectifiers, voltage regulators, etc. Of course anything is possible but that seems most likely. A failure on the primary is also possible, it may be able to supply enough for the 5VSB but unable to provide enough current to handle other rails.

[PCBONEZ]

Re: Enermax Liberty ELT500AWT fails to turn on

Glue doesn't have to be shorting high volt parts to keep it from starting.
.

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

Yeah I think in these models they still used the fucking glue which tends to be conductive over time. May be shorted or even blown secondary rectifier.

So try also to measure them with diode tester. You can do that even by measuring all of the voltage wires to ground directly.

[dmill89]

Re: Enermax Liberty ELT500AWT fails to turn on

[QUOTE=Behemot;207011]Yeah I think in these models they still used the fucking glue which tends to be conductive over time. May be shorted or even blown secondary rectifier.
[\QUOTE]

The Noisetaker 600w (circa 2006) that I recapped which would be about a year older design then the Liberty series didn't have it. It had the standard white silicon glue that most PSUs use these days. An EN351-VE (circa 2002) I recapped had the old problematic glue. The glue is easy to identify it is brown and hard/tacky. Over time it can carbonize with age & heat to make it conductive. It also becomes extremely hard and difficult to remove without damaging the components or parts of PCB it is adhered to. The internal pics I saw on Johnny Guru of the similar Liberty 620w show the standard white silicone glue so hopefully they stopped using the old glue by the time Mad Professor's Liberty 500w was made but this was right around the time they were phasing the bad glue out so depending on the exact build date it may or may not have it.

[PCBONEZ]

Re: Enermax Liberty ELT500AWT fails to turn on

KC8 found the bad glue in a Liberty.
It's posted in here somewhere complete with photos.
Very old post by now.
.

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

Yes, I had it too in mine 400W version. Fortunatelly it was not yet carbonized. I tend to remvoe this stuff in all PSUs these days, no matter what kind of glue that is. If nothing else, than I get slightly better aurflow and cooling :-)

Anyway, was that Enermax or Seasonic who made these plastic forms which keeps all components in during soldering process? They ceased using the glue afterwards.

[Mad Professor]

Re: Enermax Liberty ELT500AWT fails to turn on

Today I have removed the big heatsinks, for the pri and sec.

Pri Side
Q1 - K2750.
D5 - 30ETH06.
Q2 - IRFP460A.
Q3 - IRFP460A.
Q4 - K2607.
Q5 - K2607.

Sec Side
U3 - 7912CT.
D12 - S40SC4S.
D13 - S40SC4S.
D15 - S40SC4S.
D16 - S40SC4S.
D18 - S40SC4S.
D19 - S40SC4S.

All the S40SC4S seem to be fine, no shorts, or open.
As for the other parts I am unsure how to test with just a DMM/DVM.

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

When are the rectifiers removed, try to asure there is no other short which may prevent it from starting.

[everell]

Re: Enermax Liberty ELT500AWT fails to turn on

Mad Professor: In what country are you located. It is helpful to know if you are using 115 volts (as in US) or 230 volts (as in Europe).

It would be helpful if you would post a few pictures of your power supply.

From previous posts, I think you have APFC circuitry. If so, it is very common to have one of the FET transistors short because of a shorted booster coil. Also, you mentioned that the primary capacitor was 330 Mfd at 400 volts. Was it Rubycon or Rulycon. The two words look so close. Rubycon capacitors are high quality whereas Rulycon capacitors are rubbish.

Using DMM measure the resistance of the two IRFP460A FET transistors. If one has zero ohms between two of its legs, but the other does not, that is a good starting point. Also measure the resistance of the fuse - should be zero ohms.

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

This is former high-end, do you expect to be Ruylcon there?

If the PFC was shorted, the whole input will either burn in fire or blow the fuse, no?

[Mad Professor]

Re: Enermax Liberty ELT500AWT fails to turn on

I live in the UK, so our mains power is 230v 50Hz.

I have also attached pictures as requested.

Can someone tell me what, R15 - (Black, Blue, Silver, Gold, Green) is ment to be, as my DMM is showing it as a dead short.

[Mad Professor]

Re: Enermax Liberty ELT500AWT fails to turn on

C1 - 330uf 400v (Rubycon).
C13 - 1500uf 10v (CTC).
C14 - 1000uf 10v (JP).
C16 - 470uf 25v (JP).
C17 - 3300uf 16v (CTC).
C18 - 3300uf 16v (CTC).
C19 - 3300uf 10v (CTC).
C20 - 3300uf 10v (JP).
C21 - 3300uf 10v (CTC).
C22 - 3300uf 10v (JP).

[Behemot]

Re: Enermax Liberty ELT500AWT fails to turn on

That should be resistor, but having black stripe both first or last is strange. Could you take image of that one?