22 Feb
2009
22 Feb
'09
9:58 a.m.
*Rob, possibly you made the 110/240 switch wrong, but
also possible is
that the PSU just wasn't ready to be turned on like that.
Electrolytic
Capacitors (of which there are many in that PSU) tend towards
non-functionality the longer they sit unused. Without those caps
working right, the PSU will do pops, smokes, and other alarming things.
Then good luck fixing it.
Do you mean that it will be difficult to fix, even if I can find someone who
really knows what they are doing?
What I do with an old PSU like that is test each cap prior to it ever
being powered up.. both for capacitance and ESR. Usually, some or all
of the caps need reforming or even replacement. Only after the caps
are back to health, do I then give the PSU power... at first with the
smallest load I can get away with.
I only have a basic multimeter so I don't know if I would have had the
necessary equipment to do this, do you have any advice on the minimum
equipment needed? Now that there has been some damage is it sensible to
replace the blown capacitors and any other ones that don't measure well?
If it's a switcher PSU (as that one is), I'll bring it up quickly to
about 90V using a variac... then in 5V increments every 1/2 hr after
that to 130V, then back down to 120V. This in the USA.
I looked up variacs but there seem to be an awful lot of different ones,
again any recommendation as to the minimum I would need?
By the way, I am aware that PSUs can be very dangerous to meddle with when
you have limited knowledge. How long should I leave the PSU between any
tests to allow the capacitors to discharge? The label on the PSU says to
leave it 5 minutes, I suspect it should be longer.
jS
*