Using a PSU tester and found that the -5v light doesn't come on

[Fenrir190]

A little background info: I'm checking a friend's computer which has the following symptoms
1.) When power comes on I hear little to no sound from the computer.
* I looked inside and nothing moves, no fans no nothing.
2.) Using a psu tester and all lights except the light for the -5v rail came on.
* The tester has a slot for the 20/24 pin main connector <- this is where the problem was
* The 4 pin connector and hdd connectors all showed green on lights they were supposed to have lit.


I'm ruling it as a faulty PSU from my knowledge. Just wanted to get a second opinion before I tell him he needs to get a new PSU for the machine.

 

[Fenrir190]

After looking for a bit it seems like the -5v rail just deals with isa cards(?) and the floopy disk drive. But even still if that's dead couldn't it still point to dead psu?

 

[hunter315]

The -5 V rail was removed from the ATX standard back around 2003, look at your 24 pin motherboard connector, you will notice that pin 20 has no connection, that is where the -5 V used to be, PSUs no longer generate -5 V because it hasn't been used in years and motherboards don't take it in as they have no use for it.


A functional -5 V rail would be a scary sign as it would mean the PSU was ancient, but a dead/non functional/non existent -5 V rail does not mean that the PSU is dead.


Do the paper clip test to try to jump start the PSU, if it doesn't spin up the fan then its dead.
http://www.youtube.com/watch?v=5FWXgQSokF4

 

[ko888]

-5V was removed from the ATX Power Supply standards back in January of 2002.

When the ISA bus disappeared there there was no need for the -5V rail anymore.

 

[Fenrir190]

The -5 V rail was removed from the ATX standard back around 2003, look at your 24 pin motherboard connector, you will notice that pin 20 has no connection, that is where the -5 V used to be, PSUs no longer generate -5 V because it hasn't been used in years and motherboards don't take it in as they have no use for it.


A functional -5 V rail would be a scary sign as it would mean the PSU was ancient, but a dead/non functional/non existent -5 V rail does not mean that the PSU is dead.


Do the paper clip test to try to jump start the PSU, if it doesn't spin up the fan then its dead.
http://www.youtube.com/watch?v=5FWXgQSokF4

Thanks hunter. Yeah I'm talking with him now and the computer is an hp made around 03. Also given that information I'm now considering the possibility of a faulty motherboard. Also I was wondering if you knew it was a 20 pin connector? Even if it's a 20 pin, same rules apply still right?

edit: Sorry I never specified the connector of the PSU. Mine is a 24 pin(came out in like 2009 - 10) but his isn't.