Dim Clock LCD on Jenn-Air wall oven

[RoadsterZ4]

Thanks for the feedback. I’ll look at it deeper after work in a few days. I’ll gather some parts.

[RoadsterZ4]

Originally Posted by redwire

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.

Update:
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!

[sam_sam_sam]

I am glad you got it working again and for the time being it does not end up in the landfill or someplace like that for now

[RoadsterZ4]

Here is a quick pic from this morning. Wife loves it. Just in time for holiday cooking!

Thanks again!

[redwire]

That's great, I think some turkey gonna be cooking soon

To summarize, fixing Jenn-Air oven display:
Replace C3 68uF 35V (refurbished/newer boards upsized it to 220uF and added a resistor 27R 3W, for longer life... but they use cheap parts)
Replace C4 470uF 35V

It's a Digi-Key or Mouser parts order for under $20 incl. shipping, to fix an expensive wall-oven, keeping it out of landfill.

[Longbow]

I see that this specific subject has generated amazing interest over the years. Certainly, replacing electrolytics on the display pcb will bring back the Jenn Air (and others) display brightness.


However...these things are getting old by anyone's standards, so we have to be practical and realize that the VFD (the display tube itself) slowly ages and as it does, it becomes dimmer and dimmer. Nothing can be done about that.



The second very common problem on these stoves is that various functions begin to start up and stop by themselves. Broiler fan starts to run all the time is the usual. I have examined the control pcb minutely and found no obvious part failures. A new control pcb fixes the ghost problems. No differences can be found between a bad board and a good board. Therefore I am 99% sure that the EEPROM on the original control boards also ages (from heat) and the software finally becomes corrupted. Since it is easy to burn an 8 pin EEPROM, I would recommend that someone do just that while your control board is still working.


Then, the next problem worth mentioning is that the front panel membrane strip slowly absorbs grease, spray cleaners, etc. One or more of the functions stop working. The membrane can't be fixed and is no longer available. FYI there are several different part numbers for this membrane. The parts all look alike, but have subtle differences that can prevent them from mounting on your stove.


The final award goes to the burners themselves. The glass-covered heating elements fail after some number of years. The pull-out heating units can't be disassembled without destroying them. It is sometimes possible to find plug in units with coil-style burners. All these parts are quite expensive. Pretty soon, the price of new stove starts looking attractive. Depends upon how creative you want to be.



Good Luck,
Longbow

[bluto]

Originally Posted by Longbow

The second very common problem on these stoves is that various functions begin to start up and stop by themselves. Broiler fan starts to run all the time is the usual. I have examined the control pcb minutely and found no obvious part failures. A new control pcb fixes the ghost problems. No differences can be found between a bad board and a good board. Therefore I am 99% sure that the EEPROM on the original control boards also ages (from heat) and the software finally becomes corrupted. Since it is easy to burn an 8 pin EEPROM, I would recommend that someone do just that while your control board is still working.

You could test this theory by dumping the EEPROM on your new board and replacing/flashing the EEPROM on your old board.

[JohnJones]

Hi, the display on my JennAir JJW9827DDS double wall oven appears to be dim, so I was looking for ideas on which parts to replace. I found these images of the board from eBay.

[sam_sam_sam]

The first picture it looks like there are two caps between the two displays and they look like are swollen at the tops of them it hard to tell from the pictures that you provided but that would be the best place to start if your caps look like them