Computer Shuts Down and won't restart with out unplugging.

[Adam Zonker]

I have an Enermax 351 p-ve. and an Asus Cusl-2 motherboard. Pentium 111 933 .Not overclocked.

It will just randomly shut off as if I did pull the plug. And it will not start untill the plug is pulled and left for a while. Or I shut off the power supply using its switch and leave it off for a while, usually half an hour. I can leave it off over night when the room temp is 50 F. and it will not start in the morning unless I have "pulled the plug" .

Any ideas as to the cause?

[dood]

Re: Computer Shuts Down and won't restart with out unplugging.

Sounds like a PSU problem, most likely.

[Per Hansson]

Re: Computer Shuts Down and won't restart with out unplugging.

Yea, I had a real cheap L&C PSU do exactly that...

And also a Nexus PSU with the same behaviour, both due to bad caps and problem solved by swapping them out...

[PeteS in CA]

Re: Computer Shuts Down and won't restart with out unplugging.

I can think of two protection mechanisms that can cause this kind of latching into an off state. The first is over voltage protection. If one of the main O/Ps - +3.3V, +5V, or +12V - go out of regulation high, the OVP circuit shuts down the P/S and latches it off. Usually cycling AC power for a minute or so will reset the latch. Crap caps could allow the ripple amplitude to exceed the OVP threshold. The other possibility is over temperature protection. OTP would also latch the P/S off. Likely cause of OTP trip would be a bad fan, dust compromising the effectiveness of the heatsink, or a fan speed control circuit that doesn't increase the fan speed as the temperature rises. Given the half hour necessary to reset the P/S, I'd guess that the problem is OTP if the P/S is the problem.

[kc8adu]

Re: Computer Shuts Down and won't restart with out unplugging.

just had an enermax psu here with intermittant shutdown.
had a bad fan and crap caps.had 2v p-p on +5

[Newbie2]

Re: Computer Shuts Down and won't restart with out unplugging.

just had an enermax psu here with intermittant shutdown.
had a bad fan and crap caps.had 2v p-p on +5

Got some pics?

I wanna see.

[kc8adu]

Re: Computer Shuts Down and won't restart with out unplugging.

Got some pics?

I wanna see.

already fixed and gone.
got a better one to post later though.stay tuned!

[Adam Zonker]

Re: Computer Shuts Down and won't restart with out unplugging.

Gentlemen
Thankyou all for your fast responses.

I pulled out the PS and opened it up. Blew out the dust and I could see TWO BAD CAPS, one large one and one Small one. Both were domed (bulged) and had what looked like rust on top.

The power supply never felt hot when I touched it after it would shut off.

I went out and bought a new Enermax Liberty 500 watt 130$ Canadian.
More than I need for this computer, but I am thinking about repairing the old power supply and putting it back in, saving the new one for a new computer I hope to build in the new year.

With the new PS installed it booted fast, no hangups as before.

Okay so I have a soldering gun, do I dare try to replace the caps on my own? What am I looking at for skill level?

Thank you ever so much for the fast help.

Ps: My computer started giveing me the shutdowns last Feb. When I took it in to have the PS tested at the store I bought it from, the guy just pluged in a tester and said the PS was good. So I spent almost a year checking out the Bios, memory, fans, off on switches, heatsink/thermal compuound, motherboard and on and on.
When my 12 year old son gets home tonight and I tell him I fixed the computer, he will just roll his eyes and say ya dad just like everytime before.

HE HE . I think I did this time though.

Adam Zonker
Southern Alberta Canada
20F clear skys

[Newbie2]

Re: Computer Shuts Down and won't restart with out unplugging.

I'm guessing those two failed caps are made by PCE-TUR, a bad cap manufacturer.

What is the wattage of that soldering gun? We normally use soldering irons here but maybe that soldering gun can do the job, but we recommend 60-watts as the wattage for the soldering iron or maybe soldering gun.

Can you please post the capacitance and voltage of the two bad caps? That information will be useful.

[Adam Zonker]

Re: Computer Shuts Down and won't restart with out unplugging.

Newbie2

Your guess is right they are PCE TUR

Here is what it says on the Caps.

The small one:
105 C
0003
PCE TUR
1000 UF
10V
VENT

The large one:
105c
0002
3300UF
10V
VENT

The soldering gun I have is A Weller
60A 120V 2.5