replacement transformer wanted for IMSAI power supply

From: Eric Smith <eric_at_brouhaha.com>
Date: Sun May 9 18:50:44 1999

Tony replied to my IMSAI power supply woes:
> Pull out all the boards and disconnect the rectifiers from the
> secondaries. Does the transformer still get hot? A shorted diode or
> smoothing capacitor will make the transformer overheat...

The DC voltages were OK, which I assume means that the diodes, caps, and
regulators are OK. But next time I have the thing on my workbench I'll
check it.

> What are the ratings? Could you replace it with 2 transformers (one for
> the 16V rails, one for the 8V)? Can you rewind the old one (it's not that
> hard to do)?

I don't know about the transformer's ratings, as they aren't printed on
it or in the docs. The primary has taps for 10% overvoltage and undervoltage.

The supply outputs are rated for +8V at 28A (ripple valley to 7.5V) and +/-18V
at 4.5A each (ripple valley to 13.5V).

> It's probably easier to rewind the transformer than replace it with
> SMPSUs.

I've never rewound a transfomer, but SMPSUs are pretty easy. If I have
to replace the transformer with two or three new ones, the historical
authenticity of the power supply is already shot, so I might as well replace
the whole thing.
Received on Sun May 09 1999 - 18:50:44 BST