compaq psu

good day,

well i have here atx compaq psu that only spins its fan a second then
stops.its first symptoms was low voltage. I measure the voltage on red
- +4 , yellow - +9 should be +12. Now when i try to turn it on again,
it only produces a jolt of energy then fan stops. is it a shorted
component on the secondary side? other possibilities.

regards,

ian

 

Could be capacitors. The smoothing caps and/or the small value electrolytics
in the regulator circuit.

Dave

 

What part number?

 

What part number?

hi!
its model is HP 212
PART NO. 278740-001

 

Do you have a proper load on the supply?

 

hi,
i connected two hard disks in the supply.

 

i worked on a compaq recently that did the same thing.
it didn't like having a second cdrom(burner).
it worked fine with either drive but as soon as i put both in it would
power on for half a second then shut down.
i decided to leave out the cdrom and it worked fine.
have you tried it with just the floppy connected to see if it posts?

 

hi tom,

not yet. i'll try sooner. i also tried turning it on while no load but
w/ same effect.

ian

 

More probably the first : smoothing caps on the secondary sides, make sure
you mount low-ESR caps, you can gett them from another power supply with
another fault, (i.e. : an irreparable esemplar)