GE OTR Microwave Model PVM9215SF3SS No Heating

[rp2813]

This microwave stopped midway through a re-heating process.  Everything was dead, like it had been unplugged.  A blown fuse seemed to be the problem.  Replaced the fuse and everything came back to life.  Placed a measuring cup full of water in it to check operation.  It did not warm up.

 

The next thing to check was "the" door switch.  There are actually three things that are so described.  Two have wires going to them and one is just a plastic flipper.  I figured, the plastic flipper was likely OK or the oven would never have started up, so I got replacements for the two other switches and installed them (see image of the old switches).  Still no heating. 

 

Now I'm wondering if the magnetron is bad.  Upon starting a cook cycle, I can hear the sound of power being applied and the fan slowing.  Would this happen even with a blown magnetron?  Could the plastic flipper thing be the problem after all?  Is there a way to test the new switches with a multi-meter? 

 

Any advice would be appreciated.  I'm using a countertop model for the time being, but I'd like the counter space back the sooner the better.

 

[whitewhiskers]

re: test the new switches with a multi-meter

The switches may have molded on them a circuit diagram with the letters NO = Normally Open and NC = Normally Closed. See the attached picture, I have both kinds. That's how you would test them with the meter set to resistance. NC = 0 ohms, NO = infinite ohms.

When replacing the switches, the whole door interlock system must be perfectly aligned.
Failure of the turntable to rotate is a sign of interlock misalignment.

 

[combo52]

Not heating GE over the range microwave oven

Hi Ralph, it could be one of many things most likely in the magnetron high voltage circuit, magnetron would be by far the most likely failure, as it’s the only part that really wears out in time.

It could also be the high-voltage, capacitor, rectifier, and very rarely the power transformer.

I would probably just replace the high-voltage rectifier and the magnetron at this point.

John

 

[rp2813]

Thanks Gary and John for your input.  I have a feeling that I replaced two switches that were still good, but it didn't cost much to do so.  I'll check both old and new ones with the meter just in case the Chinese QC process was questionable.

 

The turntable did seem to be rotating fairly slowly when I did the test run, but I think that may be due to the temporary counter top Panasonic's turntable rotating at a higher RPM.  Everything popped back into its proper position with screw holes perfectly aligned, so I think the interlock system is OK -- unless that plastic flipper thing could be at fault.  It appeared to be intact when I examined it.

 

I just did a visual check to see if there could be anything wrong with the interlock and I noticed that the switch actuator is visible in the opening for the lower door latch, but there is nothing visible in the opening for the upper latch.  Is this normal?  I know each switch is oriented differently in the bracket, but shouldn't an actuator be visible in the top opening as well?  See sideways images below.

 

I want to fix this microwave because I like the control design, which features a knob to make general menu selections via its readout screen.  The knob offers the ability to bypass the touch pad, which is  huge plus IMO.

 

I'll take another look at the bracket and then check back here for replies before pursuing magnetron and rectifier replacement.

 

 

 

[rp2813]

Hi John,

 

I looked up a parts diagram and could not find anything identified as a high voltage rectifier or capacitor; only a transformer.  Do you have any leads on part numbers for either of those?

 

TIA for any help,

 

Ralph

 

[whitewhiskers]

Most likely the magnetron is bad. Part # wb27t10545, $54.99 on Amazon

Capacitor part # wb27x585, discharge before servicing or testing

Diode (high voltage rectifier) part # wb27x10597, $10, easy to test and replace
[this post was last edited: 1/26/2024-06:22]

 

[rp2813]

Thanks Gary,

 

I'll look up those parts and see if there are any instructional videos on r&r. 

 

Should I assume that the door switches properly in place?  It seemed to me that the bracket was configured in a way that the switches can only be installed as intended.

 

[rp2813]

Still No Luck

I replaced the magnetron, the capacitor and the diode.  No change.   Is there anything else I should try? 

 

To recap, a blown fuse caused the whole thing to go dead.  Replacing the fuse got all functions back except for heating.  Door switches have been replaced.  Is it possible that none of the three components I replaced today caused the fuse to blow?  Could it be the thermal protector from the old magnetron that's causing the problem?  New magnetrons don't include one, and in the video I used they reinstalled the old protector onto the new magnetron (they reused the existing capacitor and diode too). 

 

Any other ideas on what to check or replace next, or diagnostic tips to get to the bottom of this?

 

 

[whitewhiskers]

I tried but was unsuccessful in locating a schematic diagram / service manual for your oven. Perhaps an oven of similar design or brand may help. If the magnetron thermal protector was open, the oven wouldn't operate at all, which is not your case. Attaching my Sharp Service Manual hints.

Try testing the power transformer using the procedure I've attached. Not sure what else to try. It's even possible the new magnetron you installed is bad. Testing the magnetron cathode on a bench is possible, but wouldn't be conclusive.

 

[rp2813]

Thanks.  I'll look into the transformer.  I didn't see it in the diagram I pulled up but will check again or search for images if a part number can be found. 

 

The transformer will be the last major component I'll throw at this thing.  It may be some minor issue that's causing all of this, but I don't have the training to diagnose it.

 

[whitewhiskers]

Just found a schematic that more closely matches your oven. The HV power transformer is an expensive part. Just test it to see if it passes.

 

[rp2813]

Yeah, I saw the transformer prices and can't justify that much expense without being sure it's bad.  I'll see if I can find something on line that instructs on testing.  I have a multimeter but don't know if it's up to the job.

 

I have a repair guy to call and see if he can diagnose the problem if I can't.  I'd rather pursue repairing what I have than dealing with new mounting hardware and spacer installation to fill the 36" opening.  I do intend to have the original flue reconnected and then get a new OTR microwave with an exterior venting option, but in the meantime the shortest route to resolving the problem and reinstalling the oven is all I want.  This 30 x 20 x 17 paperweight (63#) on my kitchen table needs to go back where it belongs!