Transformer, full-wave selenium rectifier, and rheostat IIRC.
The one that went bang possibly needs a new rectifier, use a modern silicon one.
The one that smells of ozone probably has something arcing, perhaps the rheostat, might be normal, the sparking motor commutator of my engine always smelled of ozone.
Thanks for all the useful comments regarding flexes and earthing.
I have three Powermasters, one slightly newer, with PVC flex (old colours) and two older, with woven covered rubber flex.
Tested the newest first (none have been used for many years), plugged in and powered up, tested the outputs with multi meter, all as expected. Suddenly a fairly loud bang, the unit died and much magic smoke poured out of the vent slots. Oh. Not my area of knowledge, but blown capacitor?
On to the second, which is the one with a newly replaced mains lead. Powered up fine, but an immediate 'ozone' smell. No matter, all outputs tested perfectly. A small 'pop' but still working, so power off. Another capacitor about to expire (or explode)?
The third also requires a new mains lead, which is straightforward, and I imagine I'll be able to replace capacitors if the value is on each, and I can access them. Is that diagnosis likely to be correct?
Thanks!
If you take a photo of the innards, we might be able to spot the likely component. However, given the age there is a good likelihood that there will be caps that need replacing.
No capsd at all. Transformer anjd thetstat or or variac, and metal oxide rectifier
shorted rectifier can blow transformer.
If a selenium rectifier goes the smell is terrible & toxic. You should see what's gone bang when you open it.
NT
Pretty sure my safety minor also had some kind of auto resetting thermal cutout in there.
Was this under load though?
Widely used in TVs back in the 60s. You even got a whiff from the heat of the soldering iron when you replaced one.
Another problem is that the stink lingers and permeates everywhere.
I recall a tale in a trade mag back in the day of an engineer who'd been called out to fix the TV in which the rectifier had been decomposing very slowly.
As soon as he entered the house he recognised the smell and asked how long it had been going on for. The housholder was stunned when he foiund that the smell was coming from the TV.
They'd even called out the council's pest control officer who'd had the floorboards up looking for dead mice and rats!
Yes, the Powermaster does, too.
No. Tested with an old analogue meter only.
Apologies for delayed response - domestic stuff yesterday! Will try and take a photo or two today.
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