ScuzzBlog: Diaries November 2021

Entry 7th November 2021: Post 1: Amiga PSU - A600 High Pot Tested.

Amiga PSU - A600 High Pot Tested.

I generally act at the first sign of problems with any of the kit.
I am not an electrical engineer and have no electrical skills and
so generally work from a gut feeling. Today I swapped out a PSU
cus I just sensed something was wrong.

The PSU in question was a very heavy smaller type A600 PSU that I
was using for an A1200 with a Typhoon accelerator. Yesterday I
walked past the computer and could swear I could hear an electrical
static noise coming from the power connector to the 1200. I was
unable to replicate the problem but it was enough. What was odd
was that the PSU was switched off.

Like I say this unit is very heavy and I sense is filled with resin.
There is no obvious way to open the PSU with no screw holes. The
PSU carries the label High Pot Tested which means that insulation
used is adequate enough to withstand the high voltages. Known also
as a voltage withstand test it stresses the insulation far more
than normally encountered. Which makes me believe it is resin filled
to avoid maybe intumescent coating of the case. And fully sealed.

I have no idea, and so I decided to pull from the store a working
PSU and swap over. I only ever use A500 PSU units and it's rare to
have any other type out with computers. The one I decided to use is
evidence of the intumescent used by Commodore. It has gone very
yellow from being exposed to surface heat and therefore I decided
to exchange cases.

A few months ago I had a burn out of two resistors caused by a
faulty socket switch. The case though marked with what appears to
be cigarette burns was generally ivory in colour and perfectly
acceptable. The PSU works no problem which I base on absolutely
no electrical testing what so ever. I just make a judgement based
on my own experience. There was no sign of capacitor bleeding or
swelling of the cans. She looked very clean and no browning to
any resistors.

I gave the replacement case a scrub and photographed the damage
caused by the burning for record purposes. I also noted the place
of origin being West Germany which dates the product very well.

Anyhoo the A600 worked just fine as a test. I certainly wouldn't
have risked an Amiga if I was in any doubt. Next I connected up
the A1200 to the PSU and she is working just fine. Times like
these I do wish I was technically minded and had the skills. With
none at hand all I have is my instincts. My biggest rule regarding
PSU units since around December 1994 has been to never trust an
Amiga 1200 style power supply. Seems to have worked for me over
the years.

No more crackling static noises, and therefore can put the fire
extinguisher away for now.

Happy days... Getting colder. Whoo Hoo !!

Amiga PSU - A600 High Pot Tested.

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Last updated 7th November 2021

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