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Old 12-09-2021, 11:32 PM   #242
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Join Date: Dec 2021
City & State: aurora, CO
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Posts: 5
Default Re: Dim Clock LCD on Jenn-Air wall oven

Originally Posted by redwire View Post

The resistor does not dissipate even 0.5W normally.
I would replace C3 and C4 and test the old parts, one of them should have failed short. That's a bit weird, unless you have high mains voltage or power surges/lightning. I wonder what their operating voltage is. Test diodes D3 and D4 too.

I went down the rabbit hole a little into the circuit. Capacitor C3 feeds C4, so if C3 or C4 fail (low value) it will give a dim display. If either shorts, no display and it would burnt up the resistor.
The board has already been refurb'ed so it will be extra fragile, the PCB pads.
I received my order from Digikey -- the replacement capacitors. I ordered a few extra caps since I had to pay for shipping anyway

I removed the burnt resistor and 220uf; along with the neighboring 470uf.
Soldered in a new 470uf along with a new 68uf in the C3 position (I had to clean up the joint and contact from the burnt side). All soldered in and tested for continuity.

I reassembled and it works perfectly!! Brighter that it ever has been and all modes work. YAY!!!!!

A huge THANK YOU for all of the great information on this site and the awesome detailed responses from you - the experts. I am very grateful.
I am so glad I took electronics classes in high school back in the late 80s. It made this task a simple one.

I will keep an eye on it and I am hoping it lasts for another 20 years -- but I am sure we will replace it for a bigger and nicer one at some point.

Safe holidays!
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