power source connections

[walkinman86]

I am installing a new power source unit in an e-machines Model T-2824. My question is: Does is matter which of the 4 pin connectors is connected to which drive? The new power source has 4 pin connectors labeled P2, P3, on one lead, and connectors P4 and P5 on another lead. Does it matter which go to the Hard drive and which go to the cd drive?

 

[FlashDude]

No it doesn't matter which one goes where on the molex connectors on the Power supply Unit.

 

[walkinman86]

Ok. I have been working on an E-machines T-2824. The problem is that the machine will not power up.When I hit the start button, nothing happens; bios does not open, no fans spin, there are no beeps . nothing except a small green led located at the upper right hand corner of the CPU. I have checked the continuity at the switch and it checks out ok, I tried back probing the main power molex (20 pin connector) and found no voltages present. Cosequently, I replaced the PSU. I have checked the connections at the switch connector to a schematic I obtained fron Intel and found the connections were correct. I had tried powering up after removing the internet card---- no good. I reinstalled the internet card and tried swapping slots for the RAM---- again no good. I visually inspected all the capacitors for obvious signs of defect, (bulging and burning)---nothing. I have examined the motherboard for any signs of mechanical damage or scortching and still have not found a reason for it to not power up. Has anyone out there dealt with this sort of situation? I am fresh out of ideas and need input. I am not a computer professional, but am simply someone trying to learn something new. Actually, this is getting personal now..... it's either me or the computer, lol

 

[Law]

You have switched out for a known working PSU? Does the CPU fan and other fan in the system spin?

 

[walkinman86]

The Psu I replaced the original with is a new unit. However, until my new DMM arrives, (hopefully today), I cant backprobe the 20 pin connector to see if there are voltages present. NO fans run. The ONLY indication of any sort of power feed is that one small green LED near the upper right hand corner of the CPU.

 

[Law]

If you can test the PSU, after confirming that the new PSU definitely works I would assume there is a problem with the motherboard if the remote switch is connected properly. You know that switch that comes from the power button on the front panel of the case to the motherboard. Usually spelled as "Remote SW". New form factor like the ATX have the PSU on a wait state as of waiting for the motherboard to tell it to turn on the power when that button in front of the case is press. If this Remote SW is bad, you might still be able to turn the system on. Forgot how to do this. Get back to on that one. The reason you see that green led, is because the back of the PSU is a the on/off switch, if on it provide about 5 volts of lower current power for stuff like WAKE_ON_LAN and to provide power for the CMOS battery.

 

[walkinman86]

Ok, and thankyou as you seem to be the only person out there willing to tackle a particularly onerous problem. In answer, I cannot test the 20 pin connector,( the new dmm did not arrive today. However the analog meter registers NO voltages at the 20 pin connector).
I HAVE tried shorting out, (or crossing) the NO: 6 and 8 pins to " jump start the computer to no avail. (This last was courtesy of Scott Mueller)
If the green Led in deed indicates that power is going to the CPU, what do I try next???????????

 

[Law]

I don't think the green lead indicates that unless it's specify in your motherboard document. It probably just indicates that the PSU back switch is set to on and that the motherboard has some low current just for charging the CMOS battery. It's not enough to power the system if none of the pins on the ATX connector register any voltage.

Try to reseat the CPU.

 

[walkinman86]

Thankyou. I kinda thought that the LED might be a rather false indicator. Just because the LED lights, ( to my way of thinking), doesnt necessarily mean that power is going to the rest of the system. How, though, do I isolate the problem to determine whether it is the PSU, (which I now doubt), or some other component such as the motherboard?

 

[walkinman86]

ok, so what else do I try to diagnose the problem?