Hello!
Kenmore Model 721.636623 - three years old - 1200W.
Problem summary; Microwave suddenly started heating at about 60-65% of it's normal operation. It has maintained this level for about three weeks. No codes have shown up. All keys - including sensor cooking keys - seem to be functioning normal, other than the drop of power.

Sears Service came over and diagnosed the problem as the magnetron (fortunately covered under warranty). New magnetron was delivered and tech showed up yesterday - installed new magnetron and problem still exists. Now he says it's the Inverter circuit board (something like that). I refrained from agreeing to this repair because it's not covered under warranty, and it could be an expensive approach to start replacing components until we find the real culprit. If it turns out to NOT be the inverter circuit board, then I've spent $300 and still have a problem.

After tech left yesterday, I noticed there was a pinch/crimp in the ribbon wire where it exits the upper hinge. No exposed wires, but shows signs of being pinched hard. This ribbon wire goes to a plastic plug in type of thing on the main m/wave case. This connection seems firm, but the plastic connector is a little sloppy and moves around in it's designated space. This pinch may be nothing, but I thought I'd mention it just in case someone else had a similar problem.

Greatly appreciate everyones time, thoughts, and feedback on this.
--KevinAZ

Kevin,

I'm having the same problem. I just posted to another thread about this issue.
http://www.applianceblog.com/mainfor...26&postcount=2

Cliff

Kevin and Cliff,
About 4 months ago, my Kenmore Elite microwave 721.63663300 (1200W, made in March 2003) started heating consistently at about 50% power, based on how long it takes to heat my standard bowl of soup. Other than that, everything looks normal: display says power=100, ribbon cables are OK (no pinching) at the upper hinge, and no error messages. I have not called for service yet, because I saw your posts and wondered if you ever got the problem identified and repaired. Thanks for your time.
LoSlo

Loslo,

I replaced the 1100Watt inverter board and the main front panel mother board and it worked great, just like new, FOR TEN DAYS then it gave me the F7 error code again. The cost of both boards with shipping was around $250 so we decided to cut our losses and go buy another microwave.

We went with another Kenmore Ellite because it matches the rest of our appliances but this tiome we got the extended warranty. We thought this time we would try the combination convectionmicrowave. So far so good.

Good luck.

Cliff

Cliff,
Ever grateful for your prompt reply. I might just live with half power until I decide. In any event, the extended warranty tip will be my lesson learned. Thank you.
LoSlo