[Intel-devsys] switching power supplies
forjack842 at aol.com
Fri Aug 23 11:21:25 MDT 2019
The switchers aren't black magic. One needs a isolated variac, load resistors, stock of good ESR caps.90% of the time the caps fail due to cap aging. Like old electronics the output supplies caps need to be rep[laced.Regulation is by pulsing feed back generated by a voltage sensing circuit driving a opto coupler LED. The receiving transistorenables/disables the power inverter. Typically the 5v or 12 volt main is the controlling voltage with the rest slave regulated.
From: Herb Johnson <hjohnson at retrotechnology.com>
To: Discussion list for Intel development systems <intel-devsys at lists.brouhaha.com>
Sent: Fri, Aug 23, 2019 9:10 am
Subject: [Intel-devsys] switching power supplies
Some months ago, Bill Beech and I posted about our struggles with Intel
systems which used a now-failing switching power supply. Bill "fixed"
his by buying a modern working switching supply for modern PCs.
Recently, I was contacted by someone who has an early 1970's
minicomputer. They diagnosed by swap and other means, their particular
switching supply had failed. They wanted me to fix it; I've told them I
cannot, but I at least identified their power supply was probably an
"OEM" model not designed (or documented) by the computer's manufacturer.
That's the same situation Bill and I found ourselves in. But this older
supply produces 24 volts, which is uncommon in modern supplies. And it
may be harder to swap-in something modern.
So I'm asking: has anyone come across a repair-service, that can fix
switching power supplies "cold" - no docs, without sending them the
whole computer? I'm sure companies offer such services - a Web search
will find those. I'm asking for real (and current) experiences, not for
a Web search I can do.
Of course, many Intel development systems did not use a switcher. But
some did, and my friends here have experiences with other systems.
Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT retrotechnology DOT info
Intel-devsys mailing list
Intel-devsys at lists.brouhaha.com
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Intel-devsys