General discussion

Bad PSU? (P1 connector)

Hey everyone. Im new here and i have a problem thats really getting me angry. Here's what I have:

HP Pavilion a1630n
AMD Athlon 64 x2 Dual-Core 4600+
XP Media Center 2005

I recently shut down my computer and tried to turn it on the next morning and now it doesnt turn on at all. No beeps, no fans/lights, no activity whatsoever. When everything from the PSU is connected inside the computer, the green light on the back doesnt glow at all. But when I take out the P1 connector from the motherboard, the green light turns on. Any ideas on whats going on?

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Not sure what the P1 connector is

The green light means that the 5 volt control circuit is on. This is what allows the power on switch to begin the sequencing of the power supply. I'd have to ask what P1 looks like. If it's a square 4 pin connector it could be for the CPU but would provide 12v and shouldn't even be a factor at that point. This could still be simply a power supply. What happens if you press the power button with P1 disconnected? If the PS is good, fans and drives should start but if the connector is for the CPU it's not going to start. If no fans, beeps or drive activity, I'm suggesting power supply first.

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The P1 is the big 24 pin connector. The square 4 pin connector (P7) is plugged into the motherboard and the lights on, but only when i plug in the P1 the light goes off. Still no activity when P1 is unplugged tho besides the green light. and its not the cord cause i tested it with a different HP tower.

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Very strange

The 24 pin connector should be carrying all voltages to the MB including the 5v control signal needed to light the green LED. The 4 pin connector should be 12v and should be off. Try unplugging P1 and light the green LED and then see if it goes off when you unplug P7. P7, if its for the CPU, should be 12v and not be carrying any current at all until you hit the power on button.

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When I unplug P7 wile P1 is unplugged the LED is still lit.

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Very difficult to imagine but one more idea

If you have an Ethernet cable connected, unplug that with other cables connected. The 5v standby current would be there for such as wake-on-lan, PS2 device, etc. Otherwise, removing your P1 and P7 connectors should remove any direct connection to your PS unless you have one of those in-line 6 pin auxiliary connectors which are not that common. With a DVM this would be easier to troubleshoot. The ATX pinout shows pin 9 as 5v standby. I've checked my collection of power supplies and the wire is purple. This wire should be live any time the PS is plugged in and main power switch is on. I can't think of anything that would light the MB's green LED if all PS connectors are unplugged other than some supernatural force. Sounds like a stumper to me. You could try disconnecting cables to hard drives and such but I am curious about an Ethernet cable being involved.

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Hope its not Dead

The green LED im talking about is on the back of the computer right near the input for the power cord, not on the motherboard. no ethernet cable hooked up or anything. it just seems dead lol.

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Geesh...I can't read

You did say green LED on the back in your first post and all I could think of was 5v control voltage. It may still be that but here's what I found. See if it offers any further help.

Green LED

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Looking for your feed back I have the same problem

Have you sorted this out. I have the same problem you have. When p1 is removed PSU led switch on.
Please let me know what was your final outcome.

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