8 Aug
2012
8 Aug
'12
8:47 a.m.
I just posted the MITS Altair 8800 Power supply specs with a link to the
schematic on my web site, if you went the sensible route and bought
something new with the same characteristics the original.
http://vintagecomputer.net/browse_thread.cfm?id=486
Bill
8 Aug
8 Aug
11:37 a.m.
On 08/08/2012 08:47 AM, B. Degnan wrote:
I just posted the MITS Altair 8800 Power supply specs
with a link to the
schematic on my web site, if you went the sensible route and bought
something new with the same characteristics the original.
http://vintagecomputer.net/browse_thread.cfm?id=486
Bill
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.
Allison
1:39 p.m.
On 8 Aug 2012 at 11:37, Allison wrote:
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
6:03 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
7:52 p.m.
On 8 Aug 2012 at 18:03, allison wrote:
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!
When I added disk drives, I replaced the MITS box with an Integrand
unit which has a transformer that would make any steelworker proud.
I recently ran across the documentation and prints for it. Sadly, it
was done as diazo print, so it's pretty much all faded out.
The MITS box PSU couldn't handle the exisiting cards and a floppy
controller.
--Chuck
10:06 p.m.
On Aug 8, 2012, at 7:52 PM, Chuck Guzis wrote:
On 8 Aug 2012 at 18:03, allison wrote:
Is there any way to recover those chemically? I'd be surprised if
there weren't some permanent modification of the paper that could be
recovered either through exposing it to something or viewing it under
another spectrum.
- Dave
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!
When I added disk drives, I replaced the MITS box with an Integrand
unit which has a transformer that would make any steelworker proud.
I recently ran across the documentation and prints for it. Sadly, it
was done as diazo print, so it's pretty much all faded out. 
10:18 p.m.
I'd try photographing it with IR film. I think that's what they used on the
vindolanda tablets...
--------
Paul Anderson -- VE3HOP
On 2012-08-08, at 10:06 PM, David Riley <fraveydank at gmail.com> wrote:
On Aug 8, 2012, at 7:52 PM, Chuck Guzis wrote:
On 8 Aug 2012 at 18:03, allison wrote:
Is there any way to recover those chemically? I'd be surprised if
there weren't some permanent modification of the paper that could be
recovered either through exposing it to something or viewing it under
another spectrum.
- Dave
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!
When I added disk drives, I replaced the MITS box with an Integrand
unit which has a transformer that would make any steelworker proud.
I recently ran across the documentation and prints for it. Sadly, it
was done as diazo print, so it's pretty much all faded out.
10:51 p.m.
On 8 Aug 2012 at 22:18, Paul Anderson wrote:
I'd try photographing it with IR film. I think
that's what they used
on the vindolanda tablets...
> Is there any way to recover those chemically?
I'd be surprised if
> there weren't some permanent modification of the paper that could be
> recovered either through exposing it to something or viewing it
> under another spectrum.
I've never heard of anyone recovering this type of fading-. Diazos
were often used as proof copies because of this very property (they
go away with time). I've also got a pile of old FAXes done on
thermal FAX paper. Also unreadable.
Still, if anyone has any solid documentation on how to go about this,
I"m listening.
--Chuck
9 Aug
9 Aug
12:15 a.m.
I'm going to do some research, another mailing list I'm on has quite a few museum
people. There are some conservation experts there that might have an idea.
--------
Paul Anderson -- VE3HOP
On 2012-08-08, at 10:51 PM, Chuck Guzis <cclist at sydex.com> wrote:
On 8 Aug 2012 at 22:18, Paul Anderson wrote:
I'd try photographing it with IR film. I
think that's what they used
on the vindolanda tablets...
> Is there any way to recover those chemically?
I'd be surprised if
> there weren't some permanent modification of the paper that could be
> recovered either through exposing it to something or viewing it
> under another spectrum.
I've never heard of anyone recovering this type of fading-. Diazos
were often used as proof copies because of this very property (they
go away with time). I've also got a pile of old FAXes done on
thermal FAX paper. Also unreadable.
Still, if anyone has any solid documentation on how to go about this,
I"m listening.
--Chuck
8 Aug
8 Aug
8:40 p.m.
Thanks Bill, this is exactly what I was looking for!
------------------------------------------------
I just posted the MITS Altair 8800 Power supply specs with a link to the
schematic on my web site, if you went the sensible route and bought
something new with the same characteristics the original.
http://vintagecomputer.net/browse_thread.cfm?id=486
Bill
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days inactive
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