My microwave died and I found a shorted capacitor. Replacing the 0.9 uf
2300 vac capacitor (+/- 3%) with a 1.0 uf 2100 vac capacitor got the oven
working again with no noticeable difference from before. Can someone tell
me what changing from 0.9 to 1 uf will do to this circuit? Better yet, tell
me what the capacitor is doing? Its connected to the transformer on one
side and to a diode anode on the other. The magnetron connects to the diode
anode also. The diode cathode goes to gnd. Is this some sort of voltage
doubler? Looks to me like its a short circuit to ground for all the
positive half cycles out of the transformer, so an explanation would be
nice. Also the capacitor is +/- 3% which I've never seen before, being more
familiar with +/- 10% or even +/- 20%. Why so tight on the tolerance?

It's a half-wave voltage doubler circuit.

The value you installed shouldn't present a problem, even though it is
outside the original spec. The Voltage rating IS critical, as you probably
have guessed.

I hope you shorted that cap with a very well insulated screwdriver before
you pulled it.....

"Dan K" wrote in message
...
My microwave died and I found a shorted capacitor. Replacing the 0.9 uf
2300 vac capacitor (+/- 3%) with a 1.0 uf 2100 vac capacitor got the oven
working again with no noticeable difference from before. Can someone tell
me what changing from 0.9 to 1 uf will do to this circuit? Better yet,
tell me what the capacitor is doing? Its connected to the transformer on
one side and to a diode anode on the other. The magnetron connects to the
diode anode also. The diode cathode goes to gnd. Is this some sort of
voltage doubler? Looks to me like its a short circuit to ground for all
the positive half cycles out of the transformer, so an explanation would
be nice. Also the capacitor is +/- 3% which I've never seen before, being
more familiar with +/- 10% or even +/- 20%. Why so tight on the
tolerance?

Sorry, I just remembered you said it was short already!~) I hope you shorted
it anyway before you measured it, is what I meant to say!

"glenn P" wrote in message
...
It's a half-wave voltage doubler circuit.

The value you installed shouldn't present a problem, even though it is
outside the original spec. The Voltage rating IS critical, as you probably
have guessed.

I hope you shorted that cap with a very well insulated screwdriver before
you pulled it.....

"Dan K" wrote in message
...
My microwave died and I found a shorted capacitor. Replacing the 0.9 uf
2300 vac capacitor (+/- 3%) with a 1.0 uf 2100 vac capacitor got the oven
working again with no noticeable difference from before. Can someone
tell me what changing from 0.9 to 1 uf will do to this circuit? Better
yet, tell me what the capacitor is doing? Its connected to the
transformer on one side and to a diode anode on the other. The magnetron
connects to the diode anode also. The diode cathode goes to gnd. Is
this some sort of voltage doubler? Looks to me like its a short circuit
to ground for all the positive half cycles out of the transformer, so an
explanation would be nice. Also the capacitor is +/- 3% which I've never
seen before, being more familiar with +/- 10% or even +/- 20%. Why so
tight on the tolerance?