Topic: PSU Voltages

[zephra]

Measured 11.85volts on yellow to black which is good
Measured 3.11 volts red to black.I thought this was suppose to be 5volts.This computer is 6-7years old??

[sam]

sorry can you give more details please?

[Simon]

PSUs don't last forever.  As Sam said, we could help better with more details, like what is your reason for testing it?   The quick answer might be to get a new one.

[zephra]

Before I put this computer in storage it would not boot.I thought at the time it may be the psu.
6-7 years later here we are
 I plugged the psu into the motherboard only to power it on.With all the cd rom a drive harddrive cords unplugged I measured the volts Black and red measured 3.1volts and black and yellow measured 11+Volts.The 11 volts seems ok.The 3 volts Should be 5Volts I thought.So that tells me something is wrong.I thought the 3 volts was for the motherboard only.(which i never measured)
Anyway I plugged it in it fired up 3-4 times ok.Then it locked up under device manger and Ctrl alt delete would not respond.Had to man power down.Now it wont post @ start up.I think that it is the psu

[sam]

or the motherboard itself. what voltage setting is it set to at the back..what kind of psu is it? Also how was you measuring it? Multimeter? / what was your reference zero point? (sounding like my second year lab teaching now!)

[zephra]

Generic compaq psu.
I guess my question is
are all pSU suppose to put out 5volts to cdroms floppy and hardrive.If so my 3.11 volts is not enough.
I used a fluke multimeter to test.
I did order a new PSU

[sam]

to see what it should be i would recommend having a look at:
http://www.hardwarebook.net/connector/index.html#PowerSupply

If you are testing what I think you are testing take a look at this diagram:
http://www.hardwarebook.net/connector/power/atxpower.html