Help with getting an original Altai running: 8080A clock circuitry and MITS88 2-SIO board

drlegendre . drlegendre at
Sun Feb 7 17:03:18 CST 2016

Good point.. and if you have the later PSU with the 95,000uF 12V cap, pay
close attention to that guy.

FYI, power supplies in the Altair typically work like this: In the chassis,
there are two regulated +18 / -18V supplies of 1A each, and an unregulated
~8V supply capable of substantial current. On the individual boards, the 8V
supply is commonly regulated down to 5V (with 7805, etc.) and when needed,
the +/-18V supplies to +12V / -12V with simple zener diode shunt circuits.

On Sun, Feb 7, 2016 at 4:43 PM, Eric Smith <spacewar at> wrote:

> On Sun, Feb 7, 2016 at 3:23 PM, Kip Koon <computerdoc at> wrote:
> > I also have an original Altair 8800 that has not been powered up since I
> was
> > in my late teens or early twenties.  I'm 56 now and I was wondering if
> > anyone has put together a document for successfully restoring Altair
> > computers specifically and retro style computers in general.
> IMPORTANT: Do NOT power up until you've tested the DC power supplies
> *without* the boards installed. Check DC voltages and ripple. Aluminum
> electrolytic filter capacitors may need to be reformed or replaced.
> (But let's not restart the argument about which to do!)

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