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Microwave diode bad?

I have an older, 1998 GE Microwave oven. By the LG parts inside, probably just a rebadged LG. Lately, it's tended to 'thunk' when the magnetron turns on. A few times, it started rapidly cycling. Once, I didn't stop it in time and it blew it's 20A fuse. Another time, just starting normally, it tripped a circuit breaker.

I opened it up and checked. So far, the only obvious thing I can see is that the large diode between the transformer and ground may be open. I get infinite resistance in both directions. I assume there is nothing special about testing these types of diodes?

It's an HVR-1X diode. This appears, based on some Googling, to be very common, and the HVR-1X3 seems to be a common replacement.

Do the symptoms I describe seem to go with the way the microwave is acting? I'm not certain just what the true function of the diode is in this case (I know how a diode itself works). There is also what looks like a starter cap. It's rated at 1uF, and my meter says 1.15uF or so.

Do you think it's worth trying to replace it? I did buy a replacement microwave, but regret it. It's basically the same, but has some issues I don't like (display too far back from front, so you have to squat down to see it while typing on the panel. Fan goes REAL fast when magnetron off, then seems to nearly die when it's on.)

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Reply to
Andrew Rossmann
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That diode is spec'ed at having a large forward voltage drop (10-14 volts). I regular ohm meter will not provide a voltage that high and will show open.

Reply to
greenpjs

A microwave diode is used as a mixer at microwave frequencies. You have a microwave oven diode.

Andrew Rossmann wrote:

Check the waveguide to make sure it doesn't have food or grease in it, and that the cover is in good shape.

There are not regular diodes. There are a stack of diodes, and have a higher forward voltage drop.

That is a common oil filled HV cap. They usually fail shorted. Look at the tolerance ratings on it. It's likely +/- 20%, which means the reading is OK. Also, be careful inside a microwave. It can kill you in a heartbeat. That cap should have a bleader resistor across it. If it fails, the cap will retain a charge that will kill you.

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Reply to
Michael A. Terrell

very

Is there a simple setup I can create to test it?

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Reply to
Andrew Rossmann

I guess I'll answer my own question! I used a 12V UPS battery I had (12.89V measured) and checked if I could measure voltage through it. The diode does work and measured about 9.5V.

Any other ideas on what could cause the power surge when the magnetron is activated? The waveguide is clean. I removed the mica cover over it, and there was nothing inside.

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Reply to
Andrew Rossmann

Since there obviously lacking, their ought to be continuing education classes where illiterates can improve they're language skills.

Reply to
Spamm Trappe

That diode you speak of can not be tested in a conventional DIODE test in a DMM. It has several single diodes in series to up the over all operating voltage, each one ~ 0.6 volt drop. Most basic diode modes in DMM will only cover up to 2/3 in series. Long story short, you need more voltage to be applied to the diode for a test. Some of us have HV variable supplies, some crude, some elegant, like mine :)

A Varistate, HV transformer and HV probe works well to test these.

Jugging from your description, my guess would be a bad magnetron, one that has an intermitting short.

Jamie

Reply to
Jamie

Doing a forward test on a HV diode does not mean it's good, you still could have a break down problem with HV entered.

Jamie

Reply to
Jamie

Discussing such matters with MT is futile. Give it enough time, you'll also be editing your list.

Jamie.

Reply to
Jamie

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