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 !
Hmm.. For starters, I would recommend you do something a little bit more basic with it for the sake of increasing you knowledge from "close zero". Don't connect mains voltage to it even if it has a connector for that etc..
Playing with the display would be pretty fun. Each section that lights up is a separate LED, so you can imagine that you could light them all up all by yourself if you figure out how they are connected.
You could start with learning about LED polarity, and how to power them without risk of them burning out. After you figure this out, you could then research how microcontrollers (preferably for starters on Arduino format and the like) could let you control them.
I wouldn't recommend trying to use this boards functionality, like taking power from it and such, for now. You could return to that later, armed with more knowledge.
If you do not feel confident with your soldering skills enough to desolder the display, you could cut traces leading to it's terminals to effectively cut it out of the circuit. Those traces look like they would be easy to repair if you wanted to, but for now you could just solder wires to display on board and play with LEDs alone.
What equipment do you have on hand? Any DC power supplies? Multimeter? What kind of soldering iron?
For the chip part, it all really depends. Starting from scratch with one already embedded in an unknown board design with no documentation might be a herculean task even for experienced tinkerers. I would recommend starting small, it really goes a long way.
Thanks for your advice ! I'll give up using the board and just try using the display itself. I have a multimeter and a very cheap soldering iron, with a relatively big tip (smthg like 2mm), but i think it might be enough to desolder the display.
Using the multimeter you can find out the polarity of each LED. You could use ohmmeter, continuity, or diode mode for that. There are lots of tutorials about how to do that, you can use those keywords to look around. Your meter might not have all those modes available, you have to check and use one of them.
A bit of advice about LED in displays like those: either some of them or even all of them might have one "side" of polarity tied together. Like, all cathodes or anodes might be internally connected together just for the sake of reducing the count of terminals, and therefore traces on the board. Look out for this if something doesn't make sense while you look for individual diodes.
Do you have an idea for providing, say, 5VDC?
Do you have soldering flux and some way to wipe the tip if it gunks up?
Thanks for the tips, it seems my multimeter has all those mods.
For providing current, i'll look around me, maybe my parents have a power supply or i can get one. Otherwise i'd probably buy a 5V adapter, and use pigtails cables that i have from previous projects to connect everything.
For soldering, i use absolutely no flux, and wipe the tip on a slightly wet old sponge. I guess this is quite a bad setup, but i have very little use of it.