Power supply failed, now no boot or monitor output

Peru · 10-03-2009, 01:15 PM

Compaq Presario SR181ONX
Windows XP SP3
Integrated graphics

I know it's an old computer, but it is just used for web surfing and I would like to repair it.

What happened first:
The green light in front of the computer was flashing slowly like when it goes into standby or hibernation and yellow light (not green as when receiving a signal) was on at monitor. It was unresponsive to keyboard, mouse or even the power button in the front of the computer, so I had to switch it off at the mains.

So I put power back on after a couple of minutes. When I pushed the button on the front of the computer to start it, the green light in back of the power supply went out as the CPU fan just started to run.
I unplugged the hard drive and cd drive power connectors and tried again.
Same results.

Then:
I replaced the power supply with a spare taken from one which had capacitors fail on the motherboard. The power connectors were identical on the substitute power supply which came from an HP.

Now the cpu fan stays running on high, I do not hear the hard drive try to boot, there is no output to the monitor, and the power button still is unresponsive. I had no choice but to turn off power at the mains.

What should I do next?

Dogg · 10-16-2009, 04:47 PM

Disconnect/unplug everything from the motherboard...all cables and addon cards, including the RAM. You should simply have the motherboard with CPU/cpu fan. Then try to power up. Assuming the power supply is indeed good, and it still won't post far enough to give you beep/error codes for missing hardware, then you have another motherboard failure. You could try clearing the CMOS. But I'd give it a good inspection looking for failed components.

Peru · 10-17-2009, 07:41 AM

Yup, failed motherboard.
You win some, you lose some.

Thanks for you help.

**Tyree** · 10-17-2009, 09:42 AM

Are you certain the PSU you used from the HP was identical to the Dell PSU?
Older Dell's used a proprietary wiring system. The main power plug (20 pin connector) is standard but the wiring arrangement is not.
Using a non compatible PSU can/will cause Mobo failure.

Peru · 10-19-2009, 06:20 AM

Quote:

Originally Posted by Tyree

Are you certain the PSU you used from the HP was identical to the Dell PSU?
Older Dell's used a proprietary wiring system. The main power plug (20 pin connector) is standard but the wiring arrangement is not.
Using a non compatible PSU can/will cause Mobo failure.

The computer is a Compaq (manufatured by HP), the HP replacement supply supply is identical (including pinout and color coding). I never mentioned anything about Dell.

**Tyree** · 10-19-2009, 07:22 AM

Sorry, my bad.

10-03-2009, 01:15 PM	#1 (permalink)
Peru Registered User Join Date: Mar 2008 Posts: 9 OS: XP MCE SP2	Power supply failed, now no boot or monitor output Compaq Presario SR181ONX Windows XP SP3 Integrated graphics I know it's an old computer, but it is just used for web surfing and I would like to repair it. What happened first: The green light in front of the computer was flashing slowly like when it goes into standby or hibernation and yellow light (not green as when receiving a signal) was on at monitor. It was unresponsive to keyboard, mouse or even the power button in the front of the computer, so I had to switch it off at the mains. So I put power back on after a couple of minutes. When I pushed the button on the front of the computer to start it, the green light in back of the power supply went out as the CPU fan just started to run. I unplugged the hard drive and cd drive power connectors and tried again. Same results. Then: I replaced the power supply with a spare taken from one which had capacitors fail on the motherboard. The power connectors were identical on the substitute power supply which came from an HP. Now the cpu fan stays running on high, I do not hear the hard drive try to boot, there is no output to the monitor, and the power button still is unresponsive. I had no choice but to turn off power at the mains. What should I do next?

10-16-2009, 04:47 PM	#2 (permalink)
Dogg Tech Hardware Team Join Date: Apr 2009 Location: St Louis, MO Posts: 2,084 OS: XP sp3	Re: Power supply failed, now no boot or monitor output Disconnect/unplug everything from the motherboard...all cables and addon cards, including the RAM. You should simply have the motherboard with CPU/cpu fan. Then try to power up. Assuming the power supply is indeed good, and it still won't post far enough to give you beep/error codes for missing hardware, then you have another motherboard failure. You could try clearing the CMOS. But I'd give it a good inspection looking for failed components. __________________ Google is your friend !

10-17-2009, 07:41 AM	#3 (permalink)
Peru Registered User Join Date: Mar 2008 Posts: 9 OS: XP MCE SP2	Re: Power supply failed, now no boot or monitor output Yup, failed motherboard. You win some, you lose some. Thanks for you help.

10-17-2009, 09:42 AM	#4 (permalink)
Tyree Mentor Hardware Team Join Date: May 2009 Location: Illinois Posts: 5,746 OS: XP Pro-7RC-Mandriva My System	Re: Power supply failed, now no boot or monitor output Are you certain the PSU you used from the HP was identical to the Dell PSU? Older Dell's used a proprietary wiring system. The main power plug (20 pin connector) is standard but the wiring arrangement is not. Using a non compatible PSU can/will cause Mobo failure. __________________ Posting your PC specs will help us to help you quicker and more efficiently.

10-19-2009, 07:22 AM	#6 (permalink)
Tyree Mentor Hardware Team Join Date: May 2009 Location: Illinois Posts: 5,746 OS: XP Pro-7RC-Mandriva My System	Re: Power supply failed, now no boot or monitor output Sorry, my bad. __________________ Posting your PC specs will help us to help you quicker and more efficiently.