DIYbanter - View Single Post - Power supply (capacitor) works after months

Ralph Mowery

In article ,
says...

Getting back to your problem, I think gramps is right; it's probably a tired electro (that would be "swell"). These almost invariably work far better when heated, so if the brick was sitting in a warm area, it might spring to life. Alternatively, you can heat the brick with a hair dryer or heat gun to get it to work, but these
are only temporary solutions. Crack the bricks open and change the electros with the bulged tops. That will get most running. If not, you'll have to either ESR or replace the rest of the caps. Lower value caps on the primary side of the SMPS bricks generally go weak but don't swell or bulge.

I agree, many of the capacitors made for switching supplies seem to go
bad. Often the tops will bulge out. Sometimes heating them will make
the supply work but if you turn it off you have to heat them again.

I have replaced capacitors in several pieces of gear and that seemed to
be all that was wrong with them. I had one piece of test equimpment I
bought surplus. It was made around 1995 and cost about $ 50,000 back
then . It was to test the older cell phones. Bought it a few years ago
and sometimes it would take about 2 to 5 minuits to come on. It should
start within a few seconds. Replaced about 5 capacitors in the power
supply and now it starts up in a few seconds like it is suppose to.