[cpjr]

My sisters T3124 will not boot. fans come on but not HD light.tested PS with tester. all lights on but -5v. no damaged capacitors. will not boot to bootable disk(winXP)

[etaf]

can you get into the bios at all - to see those voltages
how are you testing , whats the tester
if you have no -5V that could be the problem ........

[Gr3iz]

The newer power supply standards have made -5V optional. I don't know if any circuitry even uses it any more.

I can see -12V still being used by the serial port (RS-232 uses + and - voltages).

[cpjr]

Originally Posted by etaf

can you get into the bios at all - to see those voltages
how are you testing , whats the tester
if you have no -5V that could be the problem ........

Can't get into bios. used a PC/SPS tester.

[win2kpro]

Start the machine and with a digital multimeter and needle probes take a voltage reading on the main plug at the motherboard pin #8 which is a gray wire. There will be a black wire right next to it, so you won't have to stretch the probes very far. Post the voltage you read on the gray wire.

[cpjr]

Originally Posted by win2kpro

Start the machine and with a digital multimeter and needle probes take a voltage reading on the main plug at the motherboard pin #8 which is a gray wire. There will be a black wire right next to it, so you won't have to stretch the probes very far. Post the voltage you read on the gray wire.

4.83 volts

[win2kpro]

If you possibly can, leave the probes connected to the gray wire and ground, shut off the power supply, wait about a minute, turn the power supply back on and see if that lead jumps above +5v.

Also, does this machine have a Bestec power supply?

[cpjr]

Originally Posted by win2kpro

If you possibly can, leave the probes connected to the gray wire and ground, shut off the power supply, wait about a minute, turn the power supply back on and see if that lead jumps above +5v.

Also, does this machine have a Bestec power supply?

still 4.83v. Delta electronics PS.

[win2kpro]

I suspect the board is shot. I never saw a "T" series with a Delta power supply, only Bestecs. If your sister didn't get the machine new, then it's a distinct possibility that the power supply has been changed at some point.

What normally happened with eMachines with Bestecs is +5vsb (gray wire) would over-volt to +12v and take out the power supply and the board. If the machine ever had a Bestec power supply there may have been previous problems where the power supply over-volted, damaged the board, but not to the point where it immediately failed. If the power supply was changed then a component that was damaged initially may have subsequently failed. eMachines has a long history of power supply/motherboard failures.

I would try this before changing the board. In ALL the following procedures, PRIOR to the procedure, disconnect the power supply from the source. Press and hold the POWER ON button for 20-30 seconds to discharge any residual power in the motherboard capacitors. Of course AFTER each procedure you will need to plug the power supply back into the source, and make sure it is on.

First remove and reseat the memory. If no changes do this.

Remove the CMOS battery for a couple of minutes, reinstall it and see if there are any changes. If no changes do this.

Disconnect all peripherals except the monitor. Remove all add in cards. Disconnect all drives. Remove all the connectors to the front panel motherboard header. Only leave the power supply main connector, and the +12v auxiliary connector plugged in. In the end you should only have the power supply, the processor, and one stick of memory installed. Take a small flat bladed screwdriver and momentarily short the POWER ON pins on the motherboard header. The machine should POST. If the board doesn't POST with just those items connected, then it's almost a certainty that the board is defective.

My records indicate the T-3124 had a FIC K8MC51G motherboard. I don't have a manual for that particular FIC board, however most FIC boards used a standard Intel front panel header pinout. A pic is attached of the pinout.

[cpjr]

Originally Posted by win2kpro

I suspect the board is shot. I never saw a "T" series with a Delta power supply, only Bestecs. If your sister didn't get the machine new, then it's a distinct possibility that the power supply has been changed at some point.

What normally happened with eMachines with Bestecs is +5vsb (gray wire) would over-volt to +12v and take out the power supply and the board. If the machine ever had a Bestec power supply there may have been previous problems where the power supply over-volted, damaged the board, but not to the point where it immediately failed. If the power supply was changed then a component that was damaged initially may have subsequently failed. eMachines has a long history of power supply/motherboard failures.

I would try this before changing the board. In ALL the following procedures, PRIOR to the procedure, disconnect the power supply from the source. Press and hold the POWER ON button for 20-30 seconds to discharge any residual power in the motherboard capacitors. Of course AFTER each procedure you will need to plug the power supply back into the source, and make sure it is on.

First remove and reseat the memory. If no changes do this.

Remove the CMOS battery for a couple of minutes, reinstall it and see if there are any changes. If no changes do this.

Disconnect all peripherals except the monitor. Remove all add in cards. Disconnect all drives. Remove all the connectors to the front panel motherboard header. Only leave the power supply main connector, and the +12v auxiliary connector plugged in. In the end you should only have the power supply, the processor, and one stick of memory installed. Take a small flat bladed screwdriver and momentarily short the POWER ON pins on the motherboard header. The machine should POST. If the board doesn't POST with just those items connected, then it's almost a certainty that the board is defective.

My records indicate the T-3124 had a FIC K8MC51G motherboard. I don't have a manual for that particular FIC board, however most FIC boards used a standard Intel front panel header pinout. A pic is attached of the pinout.

Followed your instructions. no post. I quest she will need a new mobo. Thanks so much for your help.

[win2kpro]

You're welcome, sorry it didn't work out for you and your sister.