My computer power supply has been acting strange lately. Whenever
I shut off the PC, the power supply creates a very high pitch, continuous
noise like several Cicadas on steroids. I have tinnitus so I didn't notice
the problem until recently. I'd determined that it came from the power
supply because when I pull the power supply from the motherboard
or shutdown the PC the sound gets louder. I noticed that the power
supply fan was removed when the bearing began to produce a loud
noise a month ago - that could be the problem.What part of the power
supply is capable of producing a very high pitch continuous noise
like a Cicada?

Thanks

There's often a tiny stand-by power supply that's always on. It's the
tiny transformer near the power plug. Putting a lot of spray varnish
on it may help.

BTW you'd better replace the fan pronto. PS's will run without it but
the extra heat will eventually shorten its life.

At about the time of 2/14/2006 6:26 AM, Sam Nickaby stated the following:

My computer power supply has been acting strange lately. Whenever
I shut off the PC, the power supply creates a very high pitch, continuous
noise like several Cicadas on steroids. I have tinnitus so I didn't notice
the problem until recently. I'd determined that it came from the power
supply because when I pull the power supply from the motherboard
or shutdown the PC the sound gets louder. I noticed that the power
supply fan was removed when the bearing began to produce a loud
noise a month ago - that could be the problem.What part of the power
supply is capable of producing a very high pitch continuous noise
like a Cicada?

Thanks


First thing that you need to do is put a fan in it. Those things run hot.

What can produce a squeal? In TVs, there is such a thing called a
singing flyback. I've also seen diodes and transistors do this before
catastrophic failure. Best bet is to replace the supply unless you want
to attempt to fix it. If you do work on it, there is one thing that I
want to make very, very, very clear...

### COMPUTER POWER SUPPLIES HAVE HIGH VOLTAGES ###
### EXERCISE EXTREME CAUTION WHEN WORKING ON ONE ###

I don't want to read in the paper that you were electrocuted by one of
these things. They usually quad the line voltage so they can get a
tighter regulation. This means that inside the case on the primary side
of the switcher, you have 480VDC at currents that can exceed 1A.


--
Daniel Rudy

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