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Re: [Amps] OT - Microwave oven diodes

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Subject: Re: [Amps] OT - Microwave oven diodes
From: "Val" <>
Date: Sat, 4 Apr 2015 23:31:40 +0300
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The HV diodes are usually made by a string of 1kV diodes. Every regular silicon diode "eats" 0.6V of the passed thru forward voltage and a HV string may "eat" 3 or more Volts. Most of the DMMs provide only a lower voltage that can not "feed" a string of several diodes. No current flows and the DMM read an open circuit.

The HV diode can be tested in every circuit where the voltage is more then 10V.

By the way, it is the magnetron that most likely is failed. Check the filament.

73, Val LZ1VB

My regrets to ask something much OT but
I'm guessing the answer I need likely will
be be from within this group.

My Panasonic Microwave oven stopped
working last night. There was nothing
unusual the last time I used it, it worked
perfectly. It's a particularly nice &
powerful oven with many helpful bells &
whistles and will be expensive to replace
so if I can fix it, I'd like to.

It accepts AC, displaying all the
functions it should but when engaging the
unit to heat, it stops rotating in around
two seconds and the display defaults to
waiting for a command.

My first thought is an issue with the
power supply. I located the two diodes
number UX-F5B and can't get any reading in
either direction with them in the circuit.
I expected to have some reading from at
least one of them but both show nothing on
the Fluke.

Data sheet here


I don't get a reading from the diodes in
my HF amplifier so I guess it's the same
issue. How do I check to see if there's a
blown diode in this case? & of course
there's the unknown of what initiated the

Off list reply if you would, I don't want
to start an OT thread.

Thanks & 73,


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