Quote:
Originally Posted by Techman
He bought a cheap auto wound step down transformer to run it, which although it worked, made it a genuine 'live chassis' in that all the exposed metalwork is directly connected to one side of the mains.
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That's your answer, problem solved.
When I first went to look at this chaps recorder it was when he phoned me and told me about the smoke and I said that it must be because it's intended to run on 110 volts American mains supply, regardless of the fact that someone had fitted a standard 3 pin 13 amp mains plug to it. I went down armed with a Variac and a meter and found that was indeed the case. I said it really needed an isolated step down transformer to run it safely and properly, but the next thing I heard was that he'd gone on ebay and ordered a cheap auto transformer, which arrived within a couple or three days and it was powering the whole unit perfectly. I've just looked on ebay and from what I remember it was one of these, or similar:-
https://www.ebay.co.uk/itm/155538347...Bk9SR86epqWLYg
I seem to think he also bought an American style plug to go with it. This solved the problem, it was just the live chassis and safety aspect that I wasn't happy about and I warned him that he had to make sure that the chassis was always connected to the neutral side of the mains via that transformer and what the risk would be if the neutral ever became accidentally disconnected or if both poles of the on off switch didn't break at exactly the same time that there was the possibility of him getting a belt off the metalwork as he switched it off. None of it was isolated and I quizzed him as to whether he'd received any shocks from it and he said he hadn't. I also asked him if it had ever tripped the house RCD (he said the consumer unit had recently been replaced with the latest type) and apparently there had been no tripping while the recorder was in use.
The bottom line is that the whole lot really needed running via an isolation transformer for complete safety.