Hi what I saw were open thermal fuses. One way or another it is a good reason to get rid of piles of old stuff and build new devices with 240/250V rated transformers and/or SMPS. Talema has 2 x 120V versions.
It hurts a little as mains/the grid was one of the things one could trust on. It was not designed for feedback.
It hurts a little as mains/the grid was one of the things one could trust on. It was not designed for feedback.
Once in the transformer manufacturing, failure were normally caused through loose windings that vibrate against each other and eventually the enamel shaved through. If you look at wire ratings vs wire gauge, you need a fair amount current to melt the copper windings. even if you think it is very thin. When a winding is shorted by ways of "burning through" it is in the middle of it. Cannot really happen at the end or beginning. Try and think it through. This is not what I believe or speculate, this is plain and simple. When the transformer was wound either the tension was to high and the enamel cracked or to low and the wire got nicked over a sharp edge or during the original spooling of the wire..
What was the alternative? To require everybody to swap out all their electrical appliances? What do you think they should have done?
Tom
You do have side by side bobbins and easier to fix but you still had to disassemble and reassemble the laminate. Problem was to make the transformer less noisy, you dipped it in a bucket of thick gooey varnish then vacuum the thing so the varnish gets into every nook and cranny and bake it hard for a few hours. Much easier to just replace the thing unless you have too much time on your hands.
This thread has been dragged so far off topic that posts on invertors etc split off to here (for now):
https://www.diyaudio.com/community/threads/invertors-solar-power-and-renewables.425306/post-7784364
Yes. But IIRC, it was supposed to be a phased change. Initially 230V +/- 15%, to become 230V +/- 10% at some later date.
Excuse me if my numbers aren't quite correct as this was some 45 yrs ago. Da beach bum in Cooktown, Oz dunno what the official position is today
We expected problems with the former rebel colonies with their EVIL 120V & UL. (Most product had 2 x 115V primaries in dem days) But it was in fact, some former loyal colonies which gave us trouble; possibly cos their 240V wasn't as strictly regulated. Malaysia IIRC.
This was the early days of EU certification and its RFI requirements. This had a big impact on stuff with zillion uF after their rectifiers, eg big amps. These had VERY large and short charging spikes which put loadsa RF cr*p on the mains.
It turned out simply lengthening the width of these charging spikes (which also lowered their peak amplitude) would guarantee meeting the RFI specs. You could use 'slow' or 'soft recovery' rectifiers but the simplest solution was to have a bit more resistance in your transformer.
This wasn't good for power amps but a bit more leakage inductance would do the trick too. IIRC, some PSU guru, here or in GDIY, has investigated this and published recommendations. For small stuff with constant power draw, a resistor works well.
So Mooly's little resistor has unintended benefits too 😊