8 Aug
2012
8 Aug
'12
3:03 p.m.
On 08/08/2012 01:39 PM, Chuck Guzis wrote:
On 8 Aug 2012 at 11:37, Allison wrote:
The historical cachet of the beast was all the hacks needed to make it work!
Most had been published!
FYI the usual fix was to add about 8-10 turns of wire to the winding
used for 8V
to get a bit more headroom and triple the size of the caps and make up a new
net of rectifiers using stud mount diodes for the 8V and something with
more
moxie for the +16 and -16V lines.
When I retired the best after about two years for a NS* Horizon crate
the first thing
I noted is the Horizon even with out the wood cover was way heavier and
it was
all the iron and caps in the PS!
The Compupro and TEI S100 boxes were even better as they did a better
job of
directing the cooling air and used heavy CV transformers.
Allison
its important to note the original MITS-8800 PS
was a peice of crap
and the 8800A is what you want. I have the pre-A original version and
that does not carry more than a few boards before the -8V and +12V
droops badly. The transformers and filter caps were too small.
Thanks for
pointing that out! I've sometimes thought that if I
pulled my old 8800 down off the shelf and tried to get it going
again, the first thing I'd do would be to rework the power supply to
make it something less half-assed ("quarter-assed?"). But I guess
that would destroy the historical cachet of the thing, so it'll sit
around some more. The last time I powered it on about 15 years ago,
you could see the AC ripple in the front-panel LEDs.
--Chuck