Lighted LCD microwave display is intermittent

Well, let's look at the pros and cons:

(1) You spend an hour or so tracing out the problem. You're down however much you think your time is worth.

(1a) You find and fix the problem. You're up the worth of an old microwave (maybe $10?) minus your hour's worth. I suspect you think you're worth more than $10 an hour.

(1b) You dont find the problem. You're down the time you spent. Maybe up a little enjoyment.

(2) You accidentally touch the AC line voltage terminals, or the capacitor terminakls, or the magnetron wire (2000+ volts) and die. You're out your time, and your life. And your survivors will probably feel bad to keep the oven, so they're out $10 too.

(3) You give the oven to your local charity, get $15 credit towaerd your deductions. You go out and buy a new microwave for $80, which will have a working light, a full warranty, more features, and not smell like bacon. You're out $65, but you have your life and a good feeling for donating.

Someone else basically said to buy a new oven. That's ridiculous. This could be a simple bad connection to the backlight.

But you do need to have some electronics experience to find it and understand that there may be very lethal voltages present once you remove the cover of the microwave. The controller PCB and backlight are nowhere near the microwave high voltage supply but it will be exposed. However, there will still be line voltage on the controller PCB.

What is your level of electronics expertise?

--- sam | Sci.Electronics.Repair FAQ:

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Thanks for the direct answer. I'm a retired EE with experience in troubleshooting tube based circuitry so I'm well aware of dangers of high voltage circuits. Lately, I've been troubleshooting and repairing tape decks and the some of the Tektronix 500 series scopes. Microwave ovens are completely foreign to me. I was hoping someone had dealt with this specific problem on this specific model and could efficiently guide me through the mechanical disassembly required to service the controller PCB and backlight. I'm particularly concerned about compromising the oven's microwave shielding. Paul cut Phil to respond.

That's not a concern. It's very unlikely and easy to check.

Be more concerned about the voltages. Make a discharger and short out the main cap while working on the unit. Remove short before testing.

-- _____ _ _ |_ _| | | | | | | __ _ _ __ ___ | |__| | ___ _ __ ___ ___ _ __ | | / _` | '_ ` _ \ | __ |/ _ \| '_ ` _ \ / _ \ '__| _| |_ | (_| | | | | | | | | | | (_) | | | | | | __/ | |_____| \__,_|_| |_| |_| |_| |_|\___/|_| |_| |_|\___|_| __ ____ / _| | _ \ ___ | |_ | |_) | ___ _ __ __ _ / _ \| _| | _ < / _ \| '__/ _` | | (_) | | | |_) | (_) | | | (_| |_ \___/|_| |____/ \___/|_| \__, (_) __/ | |___/

the

Since you've worked on electronics, you are aware that bad connections are a very common fault, which may be the problem here.

The disassembly will be obvious once the cover is removed and you won't be going anywhere near anything that would compromise the microwave integrity. The controller is outside the shielded area. But to be safe, do discharge the HV cap. This should happen automatically once it's powered off for awhile but better safe than sorry.

See the info - especially safety - at the sites below or

.

WARNING: There is up to 5000 V at AMPs available from the HV circuits when energies and a HV cap that can store a nasty charge. Experienced techs have been killed by microwave ovens.

--- sam | Sci.Electronics.Repair FAQ:

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+Lasers | Sam's Laser FAQ: | Mirror Sites:

Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.

Oh for gawd's sake. What's the point in the above? The guy wants to fix his microwave. His reasons are his own. He asked for help, not derision. There are others here willing to give it to him. Obviously if he's unsuccessful, he'll either live with the problem--as he has been doing--or he'll get a new one...or perhaps he'll totally destroy it.

Or, he'll fix it and keep it out of the waste stream for a while longer.

What was your point, again? Do you have one, or are you just a troll?

jak