Computer Won't Turn On

[navynuke04]

I have an HP Pavilion Slimline. It was working fine and then one day refused to turn on.

I checked the PSU and it appeared to be bad (I jumpered pins 15 and 16 and tested voltages with a multimeter and found that it wasn't putting out any power). I purchased a new power supply and installed it. Now the CPU fan will turn on for about 1 second after I push the power button, but then shuts back off. I can hear the PSU humming. If I check the PSU using the same procedure, it is putting out the correct voltages.

I put a refurbished motherboard in it and it doesn't seem to make a difference. I read that it could be due to a shorting issue, so I tried running with the MB out of the case and setting on the anti-static bag the replacement MB came in. No change.

The only cables that I have plugged in are the 24 pin power, the CPU fan, and the front panel (power button). I've tried with both RAM chips installed, and with only one installed with the same results. I've moved the password and cmos jumpers. I've pulled the battery. I honestly can't think of anything else.

Does anyone have any ideas? Could a power surge have zapped both the PSU and the processor? The processor and RAM are the only things I haven't changed out...

 

[Ken g6]

The only cables that I have plugged in are the 24 pin power, the CPU fan, and the front panel (power button).

So you didn't plug in the 4-pin or 8-pin connector to power the CPU? 😉

 

[navynuke04]

So you didn't plug in the 4-pin or 8-pin connector to power the CPU? 😉

This MB doesn't have one. Just the 24 pin connector. In fact, the original PSU only has a 24 pin connector and two sata connectors.

 

[wabbitslayer]

The only cables that I have plugged in are the 24 pin power, the CPU fan, and the front panel (power button).

is the "front panel" connector one of these where there are over a dozen or so pins (inclluding power switch, front panel usb, audio ports, etc.?)

I had a usb port that shorted out and it gave me fits for weeks trying to figure it out (doing things like spinning the cpu fan for a second, that sort of stuff). Don't use the case power switch...on the front panel connections on the mobo, look for the power switch connectors, and to turn the mobo on, take a small screwdriver and briefly touch the two terminals together. Or buy a $2 power switch somewhere and just plug that in...the goal is to rule out the front panel shorting something out.

 

[navynuke04]

Don't use the case power switch...on the front panel connections on the mobo, look for the power switch connectors, and to turn the mobo on, take a small screwdriver and briefly touch the two terminals together. Or buy a $2 power switch somewhere and just plug that in...the goal is to rule out the front panel shorting something out.

The front panel connector has six wires going to it. Two are for the power switch, two are for one LED, the other two are for another LED. The MB is simply labeled, FP1 with no specific pins labeled. It is pretty easy to see which wires come from the switch, and which pins they land on. When I short across those two pins with the connector removed, I get the same results.

 

[wabbitslayer]

well, sort of thought that was your answer.

weird that is doesn't have a cpu power connector...how old is this thing & what cpu is it???

any chance the heatsink might have been knocked loose while you were swapping out the psu? although it would take probably 5 or 6 seconds to heat up to shutdown if it were that...