Plugging in the power supply, the mobo LED light inside becomes lit. I hit the power button and the power LED light becomes lit but nothing else kicks in (fans, HDs, bios, etc.). There's a "Test Switch" on the power supply so I pressed it and held it in and the computer boots up normally as long as I keep my finger on the switch. If I were to let go, everything but the power LED light and the mobo LED light goes off. Say I hit the power button for 5 seconds to shut it off. Now when I hit the "Test Switch", the CPU fan and the power supply fan turn on but, of course, the HD and everything else won't because the power button wasn't hit. There are 5 wires coming from the power button area. Three wires are coming from to the dual-color power LED (green/red for standy mode). The other two come from the power button switch. The opposite end of the wires go to the motherboard grouped together.
It seems that the power supply is operating fine when I hit the test switch on its side. This must mean that the mobo isn't signaling the power supply to power up when the power button is hit. I can't imagine the power button being bad because the LED does light up when the button is depressed. Does anyone have any ideas what could be wrong?
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Re: power LED on but no boot up
I'm wondering if you have the jumpers set for the power button correctly on the motherboard. If the test switch is working properly when held in, then there's something wrong with the power button itself (maybe it's not going in enough to turn it on? I've had that problem before and had to McGuyver it with super glue and a little wad of paper to work correctly)
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Power supply has several voltages. Just because the 5v power is active doesn't mean all the voltages are OK. You need to have the power supply tested for 12v and 3.3v. A quick test is to unplug all the wires from the power supply. There is a single green wire on the motherboard main plug. Connect (use a bent paper clip) that green switch wire and any black wire. Plug in the power supply and it should run (fan starts)
It seems like you have bad MOBO. I recently ordered all the stuff to build 2 new systems. Built the first one, no power, just like yours. Moved everything to the 2nd MOBO, everything worked. I did a RMA on the DOA MOBO. Got the new one and it fired right up. Sometimes you just get bad stuff.
Either the board was damaged during the repair attempt, or was bad to begin with. The original problem description (black screen) sounds like typical mobo "no boot" trouble. The loose heatsink on the chip may have contributed to the failure, or it may have been simply coincidence. Given the low cost of motherboards, it's silly to spend any more time on attempting to diagnose and repair a problem. Just replace the board and move on.
Power supply is easier to troubleshoot my local pc shop has used ones for $5 or if you have one laying around make sure you have one with the proper mobo connector 24pin will sometimes fit 20 pin as long as there are no transistors to close to plug just turn pc off unplug all drives and mobo plug in good supply and turn on if it works thats the problem if not probably mobo
KingPin, is there any sign of life at all? Any lights, whiring, harddisk spinning?? Is there an LED (small light) visible on the motherboard when the power is on???
If nothing, certainly a power problem - but where. While you have the case open looking for the lit LED on the mobo, can you see any capacitors, the little cylinder-type components on the mobo circuit board that look like little batteries standing up, there'll be about half a dozen of them, that look like they may be bloated, or like a coke can left in the freezer about to explode. Do any of these capacitors look like they could be oozing goo, maybe a yellowish rusting liquid. If any do, this is not good.
If none of that applies the next step is to check your power supply. I would not suggest an amateur to do this over a step-by-step chat as it involves shorting out points and if the system is live, the wrong points shorted, well, guess you'd know what could happen (not good). The power supply is not easy to diagnos for errors, they're tricky buggers that can test well for voltage but once a load is put on them they roll over and play dead. Get an expert to test your power supply, very simple task of they plugging in a PSU tester (or borrow one, or buy one).
Please keep us informed on how you go - seriously, we grow stronger as we grow wiser when we finish a job.
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Try a new power button. Also does the machine power light turn on at the front of the machine? if so check that the CPU is seated correctly as if it has come out of position then the machine doesn't boot. I would like to think power switch though.
it could be your power switch, veriy that it isnt the power supply by
1.) un-plug it from the main board
2.) look at the main board connector(one coming of the power supply)
3.) you should see green wire and next to it a black one
4.) using a paper clip bridge the too wires
5.) if it works proceed to net step if not get a new power supply
to check case switch and board switch
1.) plug in power supply to main board
2.) look at the pins where the power button connects to
3.) using a metal object (blade screw driver) bridge the pins
if the board should start up>
then its your power button on the case that is bad, you can try to repair it, chage it or buy a new case,
if it doesnt work.
1.) ensure that jcms(jumper to flash the bios) is set correctly
2.) unjack each drive one at a time to see if any is causing stalling
3.) get a new main board