"Sam Goldwasser" wrote in message
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"Arfa Daily" writes:

wrote in message
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On Jun 19, 5:05 am, "Tim Williams" wrote:
wrote in message

...

there should be 2 diodes near the microwave magnetron

Nope, only need one. The magnetron is the other.

Tim

--
Deep Friar: a very philosophical monk.
Website:http://webpages.charter.net/dawill/tmoranwms

well on schematic there is another one in parallel with the capacitor
(guess for protection)but its orientation is not clear-probably
should be anode to magnetron and cathode to transformer, as drawn

My Sharp has one in series with the mag, which I guess is the HT
rectifier,
and one in shunt across the HT filter cap, orientation as you suggest.

Circuit please.

Where is the HT filter cap?


You've got me thinking now, Sam. The reason that I said about my Sharp, was
that I had occasion to be inside it a few weeks ago. I actually have two of
these - one at home, and one in one of our businesses. The business one
failed, and it was the HT rectifier that had gone short circuit, and knocked
out the HT fuse. I didn't take that much notice of the circuit overall. As
far as I recall, the diode went straight from the HT winding on the tranny,
down to one terminal on the HV cap, and I'm sure from there to the mag, but
that is only from memory. There was a second diode connected directly across
the HV cap. I know for sure that it was there, as I disconnected it to check
it. I was just thinking standard half wave rectifier circuit - one diode,
one cap. I didn't really even consider why that other diode was there. But
now I do stop to think about it, that isn't 'normal', is it ? Usually, the
cap is connected to the tranny, and the rectifier is in shunt, and produces
negative HT to the filament / cathode, the anode being grounded to the other
side of the HT winding ... I suppose if you think about it that way round,
and then put it down on paper 'conventionally', it amounts to the same
thing. It's just the way that the circuit is usually drawn that makes it
seem something different. A bit like getting your head around PNP
transistors connected upside down into a 'positive up' circuit.

In the next couple of weeks, I am going to be scrapping my one at home, as
part of a rebuild of my kitchen. It has always been an 'uncontrollable'
piece of crap, far too powerful to be of any use, anyway, so I shall be glad
to see the back of it. Before it goes, I will take another look, and see
just what they have done in there, circuitry-wise.

Arfa