12 total posts
what PC or what mobo? AT or ATX power supply?
Mobo jumpers are often a pain to figure out connection to a new front panel.
Re: more info
OK, it's an ATX power supply... Both of them, which give the same results.
We've also since tried swapping in an old video card to see if that was maybe the problem, no change.
As best we can tell from the mobo manual, the power switch connector is on the right pins, and we've tried switching them around just to see.
Any chance when he changed to a different case
he shorted out some mobo artwork to a hex standoff in the wrong place???
Does the systemseem to be booting, just that you can't get video. Normally this condition would give a number of beeps.
You might be down to putting the mobo on a sheet of cardboard to totally isolate it from the mounting plate. It should be grounded to the mounting plate but ONLY via the mel standoofs under the holes in the mobo that have copper rings plated around them. Nothing else.
(NT) mel standoof = metal standoffs. LOL
Re: Any chance when he changed to a different case
It's a possibility. It's the first time he's done anything like this, and so he missed the bit about the standoffs. The mobo was screwed onto the mobo tray. In his defense, it is VERY hard to see the standoffs in the old case, they blend so well color wise. Unless you're looking for them, it's easy to miss them.
I've looked over the mobo, and can't see any obvious signs of damage top or bottom.
So far the HSF and video card both get power enough to make the fans run, and the power switch (on the front of the case) does work now, but still no video at boot.
Basically, we're just trying to figure out what, if anything, is broken to assess what move to make next. Whether to just get a new motherboard and cannibalize the rest of the parts, or if he should just sell the parts off and put the money towards a new system.
Take the mobo off the mounting plate
IMMEDIATELY. Isolate it ona piece of cardboard. May not have damaged it. Maybe just grounded some of the artwork disabling the system. With luck he didn't gouge the artwork, burn out a section or cut a land and open it.
Re: Take the mobo off the mounting plate
well, right now it's up on the standoffs like it was supposed to be the first time around. We don't really have any sheets of cardbord like that unless we cut up the box the case came in. Something he'd rather not do unless you think it's rather necessary.
No need to put it on cardboard if you
are certain that it is mounted properly.
When this system was working in the other case, did it normally beep at startup [not all BIOS's give beeps].
If it did before and doesn't now, that's not good. [as you well know].
The power switch wiring and the reset switch wiring are not polarity sensitive [the switch simply ties the two wires together momentarily. Thus you can leave the wires off and simply touch a small screwdriver blade to the pair of pins momentarily.
Moving the mobo from one case gives great possibility for having zapped something by ESD and, of course, mounting the mobo directly to the mounting plate could easily have damaged something.
Rereading your first post re CPU and mobo power connector, I find it not clear. Certainly you have the HSF on the CPU. Does your mobo [and power supply] use the 4 pin connector for 12 volts?? Could this be what you mean by the CPU power. You still need the main PS to Mobo connector connected. Maybe clarify.
Do you have a voltmeter??
Is the 5 volt logic power on the mobo? [it should be there anytime the PS has AC Power applied to it.]
Re: No need to put it on cardboard if you
well, the mobo isn't touching the mounting plate at all anymore.
I am a tad worried that the mobo got zapped, which is seeming more and more likely. He'll be taking it to a repair shop tomorrow to see if they can figure out exactly what component is faulty. Because it would beep when the POST had completed, and now I'm getting squat.
And to clarify on the connections. There's the normal 12-pin connector that's common to every motherboard. Then there's a second 4-pin connector which AFAICT feeds the CPU directly. Think all AthlonXP mobos have such a connector, and P4 systems have something similar. Not exactly sure the voltage of it, since sadly we're lacking most of the basic tools of an electrician.
That four pin connector is the 12 volts
to power the CPU. It has two 12 volt wires and 2 returns [grounds]. Intel mobo's started powering the CPU's from 12 volts, and wrote the ATX V12 2.01 power supply spec well before the AMD mobo's went to use the 12 volts.
It was done to reduce the current levels in the wiring as the CPU's consumed much more power from the 3.3 bus. The current decreases by the ratio of 3.3 over 12 = 0.275. That 12 volts in new supplies comes from a separate 12 volt regulator than the 12 volts going to the normal mobo connector for the drives, fans et al. [often referred to as rails].
Also, I hope that the 12 pin connector
is actually 20 pin, if it's an ATX system. [unless it is a proprietary type system. If it were then one must get that mfr's Power Supply]