Old Power Supplies, revisited

From: Louis Schulman <louiss_at_gate.net>
Date: Sat Apr 27 22:07:15 2002

I am putting my SWTPc 6800 back together, after complete disassembly
for cleaning. So, on to testing the power supply.

It works! But here's the question, which I know has been discussed
before with respect to S-100 machines.

The power supply is a big transformer with one really big (91,000 ufd)
capacitor, and the usual rectifier stuff, etc. The documents call for
7-8 volts unregulated, along with + and - 12V.

I am getting something like 9.3 V, and + and - 14.3 V. Are these
voltages too high? Of course, on the SS-50 and SS-30 cards there are
voltage regulators, but I don't want to cause any damage. This thing
probably hasn't been powered up in 25 years.

How can I check the capacitor function without an oscilloscope or other
fancy equipment? Should I worry about "reforming" the capacitor?

Thoughts appreciated.

Louis
Received on Sat Apr 27 2002 - 22:07:15 BST