(no title)
failedengineer | 3 years ago
This doesn't happen under normal operation, because the chassis allows for a short and/or a ground fault. But when you take that chassis off, and especially when you take the transformer out, you're putting yourself into a life threatening situation.
TL,DR: Microwaves cook things, including you.
hilbert42|3 years ago
Much of my learning was on vacuum tube technology (often of the HV transmitting kind) and almost invariably anode supplies etc. are isolated from the mains so relying on ground-fault detection is, as you say, a waste of time. Actually, a microwave oven is a high voltage vacuum tube (magnetron) transmitter and should be treated as such.
My experience has been that it's easy to become careless and blasé through familiarity and that's when nasty things happen.
Every time I've been zapped (and it's been many) it's been through carelessness. Fortunately, most of those shocks were of the 250-400V DC variety inside a chassis where it was only my hand that was between the 'hot' point and earth.
Nevertheless, I've also had a few very close shaves and I shudder even now whenever I think about them. One was on top of a microwave tower in a rainstorm whilst adjusting a klystron that had slipped outside its AFC/S-curve range. It was fed with a -1500V (on the heater circuit which one usually thinks of as being at ground potential) and the other supply was +800V at the collector. Water was everywhere. To make matters worse, at the time I was standing on wooden 2x4s outside the tower which also supported the link. It was over 150' to the cement below. Right, I must have lost my presence of mind.
I don't mention that just for dramatic effect (after all, it's quite embarrassing that I could be that stupid), rather it's to show how easy it is for this 'blasé' effect to take hold when one's wrapped up in the minutiae of what one is doing.
One thing I've learned is that once one's equipment hits 400/500V and up things become very different and much more dangerous. For starters, component layouts often change due to large components and HV wiring often isn't located in just one part of the circuit but rather it can amble widely. Moreover, manufacturers aren't consistent in labeling the HV parts of the circuit. Where possible, one should always try to keep one of one's hands in one's pocket. ;-)
In some ways the problem is worse nowadays as everyone is now used to working on low voltage solid state devices, thus most will never encounter very high voltage electronics until they open their MW ovens and come across its magnetron's HV power supply. It's a worrying problem as many such ovens have inadequate or no HV warnings inside the case.
Incidentally, not long after posting my comment I noticed a few people down-voting it without comment. Sometimes I think I should not interfere and let evolution follow its normal course (as it nearly did with me).
folkhack|3 years ago
Often you'll catch downvotes for playing devil's advocate, even when it's very justified like in this circumstance.
I'm one of those low voltage DC noobs and I was still shocked when I saw the title... I was even more shocked by the wood burning article - people are dying playing with this stuff. If anything that Linux-powered microwave article should have a huge warning at the top outlining the risks.
I appreciate you taking the time to educate on the dangers + sharing your anecdotes.