So last summer, our oven/mw (Whirlpool JQ280) broke (i'm thinking of overheating since it was very hot, but it may as well be electrical default). I tracked down the problem to the motherboard, which has indeed some weldings that burned. I bought a new one and the oven is working again.
I now have this defective motherboard, separated in two parts. The burned weldings are on the back part, and the front part still has a four-number display, a button and what i assume to be the main chip. I figured that i maybe could get only the front part and make some kind of clock with it.
The easy version would be to feed it 5V current, and if it's not broken it should work as if it was still in the oven, providing a time display. Is there anything dangerous or tricky about that ? I already built/modified a few electrical circuits (spotlights, guitars) but it was always with simple components used for their intended purpose, and i have close to 0 knowledge of electronics. I specifically have no idea if there might be danger of electrical shocks and if it's important to ground it (There are two circuits that are labeled GND on the connection between the two parts, and a yellow/green cable that was connected to the metallic structure of the oven going from the bottom of the back part).
The more complicated version would be to also reprogram the chip, out of curiosity. From Internet, i deduce that it takes some specific hardware to "flash/burn" the chip : either some box in which you put the chip, either some clip that you put around the chip. The problem here is that the chip of this motherboard seems to be 64pins : i think un-welding/re-welding it would be far beyond my welding skills. But on the other hand, it doesn't seem to exist clips adaptators for more than 16 pins. Can you confirm that reprogramming this chip would involve precision welding ?
Anyway, thanks in advance for your feedback, have a great day !
Your more complicated version is untenable for many reasons, the least of which being that I would bet $10 that microcontroller is write protected even not knowing what chip it is (hc11?)
You could drive the display but something on that board blew up. Hard to tell from the pictures but it appears the area around the connector labeled nfs and the black box labeled fcvm 4907 (relay?)
If you simply feed voltage into it it will likely not work. You can get the screen to turn on this way but it won’t function as a clock, something has to send it the logic (that chip). This may still work but you’d have to power the full board and not just the LEDs and the chances are much higher that that burned section has more dead parts surrounding it preventing operation
You can trace to see what’s dead, then try to figure out what killed it, then try to fix it and power the board externally. If that is a relay and the oven was old (or even if it wasn’t and just had shit soldering) the fix could be relatively simple. Relay failure isn’t uncommon on whirlpool boards and cold solder joints are super common on modern appliances. Cold solder joint switching 10-15A at 120-240V will crack/weaken and eventually arc. If you’re lucky it just killed the relay and the fix is easy, just clean the board, swap the relay, fix any cold joints that remain (though it’s less important now that it’s not doing its actual job) and hope that it didn’t destroy a bunch of other stuff when it died
You could also just pull the screen and use it with an arduino or something. You’d have to reverse engineer the pinout but with a screen like that it should be stupid easy to do and that’s actually a pretty good slightly advanced beginner arduino project tbh. Then you could make a custom clock, animate it how you want, etc