Thanks for your input. Here is what happened:

After testing the output voltages on the PSU and finding them to be a
bit off-target, I did a touch of soldering to eliminate the dry joint
possibility. Unfortunately I think I may have killed a couple of the
more sensitive components (all soldering was done on the low-voltage
side of the board). Upon plugging it back in there were several flashes
followed by a blown fuse. On closer investigation with my trusty
multimeter, I found the live side to be completely shorted. Once I
desoldered and tested a few components, I found three of the four
rectifier diodes were shot. I imagine it must have been a pretty
catastrophic problem on the low-power side to have caused this! (and
no, there are no shorted tracks) I **think** I may have seen the
L7812cv rectifier IC flash in the process.

Just to add to the problem there is a signal diode that has shattered,
and is now unreadable. Other than that there are only a couple of
sensitive components, so I guess it may well be easier to try and fix
it. Does anyone have a schematic for this? I realise that these units
aren't really made to be repaired, so there is a good chance that one
doesn't exist.

Anyway, thanks again for your help.



On Nov 18, 1:48 pm, "Arfa Daily" wrote:
"James Sweet" wrote in messagenews:9os7h.95$mM1.63@trndny08...

fredrickew wrote:
Sorry, just noticed that there are two more rails also, a -12v and an
AC3.9v. I'm not sure if the AC is refering to Alternate Current or
accessory. I'm pretty sure it would be a dc rail though.

The AC voltage is for the heater in the VFD display. You'll spend a lot
more time re-engineering a PC power supply to work than you will just
fixing the original.Likewise, the -27v is also for the VFD. The 3.3v will be the CPU core
voltage, so must be properly regulated. If you have done damage beyond the
original PSU fault, it's probably not worth wasting more time and effort on.
Just what additional components do you think you have fried ?

Arfa