"hemyd" wrote in
:

"Bill Jeffrey" wrote in message
news:1Uxae.64116$A31.36134@fed1read03...
I'm surprised that this hurt anything. If you plugged it into 110,
but set the switch to 220, then the power supply was seeing only half
of the primary (i.e., input) voltage it was expecting. Because of
this, it was probably unable to produce the proper secondary voltages
(5VDC, 12 VDC, etc) since the regulators ran out of headroom. But I
wouldn't expect this to damage anything in the power supply. And I
can't think of anything on the motherboard that would be hurt,
either. I'm not as sure about the display's deflection circuitry,
assuming you have a CRT monitor - but the display isn't powered
through this switch.

With the switch correctly set, can you measure the power supply
secondary voltages?

Interesting question. Please let us know what you find.

Bill
=======================

I tend to agree. here in Australia we run on 240 volts. Setting a
power supply on 110 volts would produce a short sharp bang, and
the power supply would be stuffed, however, in the reverse situation,
I cannot see off hand why inputting half the voltage for which it was
set would damage it. I suppose with modern power supplies there could
be other factors where even that scenario would produce a failure.

Henry.




IMO,at half nominal input voltage,the switcher would not start.
Should not,if properly designed.

At 2X input V,yes,the switcher transistors would blow quickly...then the
fuse. 8-)

--
Jim Yanik
jyanik
at
kua.net