Re: Lighted LCD microwave display is intermittent

On 21 Sep 2006 08:36:44 -0400, Sam Goldwasser <sam@xxxxxxxxxxxxxxxxxx>
wrote:

Makull <makull1@xxxxxxxxxxxxxxxx> writes:

Our Sharp built in microwave, model no. R-420DK, hasn't had a LCD
display that was easily visible (especially at night) since we bought
the house 3 months ago. The light for the display came on yesterday
and today while we were using the touch pad. The light stayed on for 5
or 6 seconds each time and went out when we opened the door or punched
another button on the touch pad.
I'd like to try to troubleshoot and repair the LCD light circuit, and
need info on safely accessing the lighting circuit.

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?

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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 <makull1@xxxxxxxxxxxxxxxx> cut Phil to respond.
.

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