Yep. I needed the circuit diagram for my microwave to fix an issue with the light (kept blowing out bulbs rapidly). Turned out you have to pull it out of the top inner frame, after unscrewing the button board and top panel. Thankfully, was an easy soldering fix, thyristor blew.
Generally microwaves are amongst the devices I tag as “do not self repair” I lack the confidence in my repair skills to fuck with the machine with giant caps and built in death ray.
Discharging capacitors (and anything else that might hold a charge) isn’t that hard and dangerous if you know how. I used to work on radar systems with 32KV on big capacitor banks.
1: Connect a thick, beefy wire to a solid and reliable ground connection.
2: Rig up a way to hold that wire in a well-insulated way, so that you have thick, non-conductive insulation between you and the wire, but you can still move it around freely and easily.
3: Firmly touch the tip of that wire to the contacts of any capacitors you can see, any bare metal contacts you can see, and anything else that might be at all dangerous. If in any doubt at all, touch the wire to it. Do it twice, just to be sure you didn’t miss any. (There may possibly be sparks when you do this. That’s okay – it means it’s working. Do make sure you’re not close to anything that’s very flammable, though.)
After doing that, everything will be discharged and completely safe to work on.
For something the size of a microwave, you could build a capacitor discharge tool very simply and easily by taking any three-pronged power cord, cutting it in the middle, disconnecting and isolating the two power connections (leaving only the ground connection), leaving a bit of bare wire from the ground wire exposed at the end, and then wrapping your handle area in some extra layers of electrical tape (just in case some of those capacitors have voltages above ~300V). (Or if you want to be ultra-safe, tape a plastic or wooden handle to the wire instead.) Plug that modified 3-prong cable into any standard 3-prong household outlet to connect it to a reliable ground.
If you want to be a bit more professional about it, a grounding wire from an ordinary welder setup should be able to safely discharge just about anything you’d ever encounter.
You obviously have the experience and tbh that might be the best guide I’ve seen on building a capacitor discharge tool (it might also be the only one, but it seems to make sense). For the sake of completeness I assume I plug in the plug and it’s just using the house’s earth?
Not sure how possible it is to reassemble it in an unsafe manner with the magnetron in the mix and I’m not sure how much peace of mind I’d have using it afterwards. But I certainly feel a lot happier about discharging big caps now.
Haha, I thought I better check to be sure. It’s such a fantastically straightforward sensible concept for a tool I’m honestly not sure why it’s not everywhere vs people shorting caps with a screwdriver.
Crimping a push fit terminal of some sort on the end would make a handy static wrist strap hookup too I’d imagine.
If it was a problem with the microwave function I don’t think I’d have bothered. I’m terrible at repairing things and break most things worse than they were before. But it was the lightbulb acting up (the underside one, we’ve got an over-range mounted unit).
In this case I had the circuit diagram and multiple YouTube videos to lean on. Thankfully the thyristor is big, because I’m terrible at soldering, but it worked out.
Yep. I needed the circuit diagram for my microwave to fix an issue with the light (kept blowing out bulbs rapidly). Turned out you have to pull it out of the top inner frame, after unscrewing the button board and top panel. Thankfully, was an easy soldering fix, thyristor blew.
Generally microwaves are amongst the devices I tag as “do not self repair” I lack the confidence in my repair skills to fuck with the machine with giant caps and built in death ray.
Discharging capacitors (and anything else that might hold a charge) isn’t that hard and dangerous if you know how. I used to work on radar systems with 32KV on big capacitor banks.
1: Connect a thick, beefy wire to a solid and reliable ground connection.
2: Rig up a way to hold that wire in a well-insulated way, so that you have thick, non-conductive insulation between you and the wire, but you can still move it around freely and easily.
3: Firmly touch the tip of that wire to the contacts of any capacitors you can see, any bare metal contacts you can see, and anything else that might be at all dangerous. If in any doubt at all, touch the wire to it. Do it twice, just to be sure you didn’t miss any. (There may possibly be sparks when you do this. That’s okay – it means it’s working. Do make sure you’re not close to anything that’s very flammable, though.)
After doing that, everything will be discharged and completely safe to work on.
For something the size of a microwave, you could build a capacitor discharge tool very simply and easily by taking any three-pronged power cord, cutting it in the middle, disconnecting and isolating the two power connections (leaving only the ground connection), leaving a bit of bare wire from the ground wire exposed at the end, and then wrapping your handle area in some extra layers of electrical tape (just in case some of those capacitors have voltages above ~300V). (Or if you want to be ultra-safe, tape a plastic or wooden handle to the wire instead.) Plug that modified 3-prong cable into any standard 3-prong household outlet to connect it to a reliable ground.
If you want to be a bit more professional about it, a grounding wire from an ordinary welder setup should be able to safely discharge just about anything you’d ever encounter.
You obviously have the experience and tbh that might be the best guide I’ve seen on building a capacitor discharge tool (it might also be the only one, but it seems to make sense). For the sake of completeness I assume I plug in the plug and it’s just using the house’s earth?
Not sure how possible it is to reassemble it in an unsafe manner with the magnetron in the mix and I’m not sure how much peace of mind I’d have using it afterwards. But I certainly feel a lot happier about discharging big caps now.
Yes! Heh, I guess I forgot that part. I should add it in, just in case.
Haha, I thought I better check to be sure. It’s such a fantastically straightforward sensible concept for a tool I’m honestly not sure why it’s not everywhere vs people shorting caps with a screwdriver.
Crimping a push fit terminal of some sort on the end would make a handy static wrist strap hookup too I’d imagine.
Plus, you’d get to see the horrified looks on your friend’s faces when they see you plugging your wrist strap into a wall outlet!
If it was a problem with the microwave function I don’t think I’d have bothered. I’m terrible at repairing things and break most things worse than they were before. But it was the lightbulb acting up (the underside one, we’ve got an over-range mounted unit).
In this case I had the circuit diagram and multiple YouTube videos to lean on. Thankfully the thyristor is big, because I’m terrible at soldering, but it worked out.