TheVille

This one has me stumped. I'm trying to donate one of my older computers
to my son's scout troop. I reinstalled windows, did all of the updates,
installed all of the software they will need, and ran it for a couple of
days to insure everything worked. I took it to them at their next
meeting, plugged it in, and it would only turn on the green power
light. No fans, no drives, just the light. I brought it home and
plugged it in and it booted up just fine. I went over all of the
connectors just to be sure everything was connected, stressed tested it,
and took it back today. Same thing. I tried 12 different outlets in 5
different rooms. Yet the old computer they have (Compaq Evo, P4 socket
478) starts up ok. The power supply in the computer I am donating is a
PC Power and Cooling 350W ( I don't remember the model).

Let me repeat: It works just fine at home, but not in their building.

That's incredibly strange. The fact that you could go back and forth with it and repeat those results makes it even stranger (eliminates something getting jostled in transit, for example).

I'm no electrician, but I wonder if it's possible the troop's building has a power issue that the PSU is detecting and based off of which it is refusing to operate? Something like a shorted ground wire or something? Or perhaps the building has a an incredibly weak feed and can't supply the amperage needed? Electrical Engineers, ho! Come save us?

I'm taking a meter to the next meeting.

Yes. I agree with the above. Voltage, current, frequency. Or of course, demonic possession.

Might have to submit power supply to ALS ice bucket challenge. If it's good it will pass.

Older PC may have less sensitive power supply.

Take a UPS to the scout building and see if it'll boot with the UPS between the wall and computer?

Flash wrote:Take a UPS to the scout building and see if it'll boot with the UPS between the wall and computer?

Yeah...I think I might know someone who would loan me one for the day. Outlet tester, volt meter, and a UPS.
Also looking at a new PS....just in case it might be the problem.

It's most likely a safety device in the power supply because there is voltage on the ground line. Break off the ground prong or use an adapter for sockets that don't have a ground and see if that will work. Turn off when not in use.

The Spanish Inquisition wrote:It's most likely a safety device in the power supply because there is voltage on the ground line. Break off the ground prong or use an adapter for sockets that don't have a ground and see if that will work. Turn off when not in use.

Ah! Good idea. I'll try that too.

Any updates on this mystery?

Fascinating...

https://www.youtube.com/watch?v=cFods1KSWsQ

Have not been able to get back to the building as I have not been able to get mondays off, but I am suspecting that the voltage at the outlets is under 100 volts. The P/S I have in that computer has passive PFC and I think the minimum voltage on that unit is 100 volts.

Update:

I have found out that the voltage at the outlets averages about 122V. The power supply does have a switch for 115/220, and I made sure it was set to 115. I think the P/S has passive PFC, so would anything over 120V cause it to not power up? Also, I plugged in an outlet tester, and the outlets seem to be wired correctly.
Do you think I should update the P/S with one that has active PFC and has automatic voltage selection, or maybe try a UPS?

Most of the incoming AC power these days is going to be 120ac with a varience of + or - 3 %. The old allowable voltage was 115 ac with + or - 3%
If it's an older PSU I'd look into replacing.
And with the voltage being 120 it will cause the PSU to over volt and not power up.

<eVa>mlite wrote:Most of the incoming AC power these days is going to be 120ac with a varience of + or - 3 %. The old allowable voltage was 115 ac with + or - 3%
If it's an older PSU I'd look into replacing.
And with the voltage being 120 it will cause the PSU to over volt and not power up.

I kinda suspected that when I saw the voltage numbers. At home I'm running about 116V. *sigh* It was a good P/S for years without a hiccup. Only reason I updated it was for a new video card.

FIXED.

I finally replaced the P/S with an Antec VP450, and it's working just fine.
The old P/S (PC Power and Cooling Turbo Cool 350 ATX) will still power up at home, though. I have to assume that it's on its way out, as I can't see why a 6 volt difference would cause it to not power up at the church (116V at home vs 122V at church).