Altair-what do I do first

From: Ross Archer <archer_at_topnow.com>
Date: Tue Sep 24 21:31:00 2002

"J.C. Wren" wrote:
>
> A less painful way may be to lift the output pin of the regulator from its
> via. Or (and this is evil, but works, and is can be better than losing all
> your unsocketted chips), cut the trace after output of the regulator. You
> can always use a piece of foil tape or wire to effect a repair. This may
> detract from the ultimate value of the board, but you're far less likely to
> wreck it than removing irreplacable socketted chips.
>
> --John

And if all this seems like too much trouble, I'll be happy
to take
this odious burden off your hands. :)

Merely email me for my shipping address. :)

-- Ross

>
> -----Original Message-----
> From: cctalk-admin_at_classiccmp.org [mailto:cctalk-admin_at_classiccmp.org]On
> Behalf Of Tony Duell
> Sent: Tuesday, September 24, 2002 20:24
> To: cctalk_at_classiccmp.org
> Subject: Re: Altair-what do I do first
>
> >
> > Good move -- don't plug it in yet.
>
> _Neve_ plug in a classic computer without checking it first!
>
> [Good advice on electrolytic caps deleted]
>
> > In any case, detach everything from the power supply and check it out
> first.
> > Unfortunately, Altairs have no connectors for this, so you will have to
> > desolder the wires.
> > Some suggest powering it up slowly on a variable transformer, but I have
> not
> > tried that.
> >
> > After checking out the power supply voltages, unplug all of the cards and
>
> The amin problem with S100 systems is that the PSU lines on the bus are
> unregulated. The voltage regulators are on each card. And this means that
> a defective regulator _on a card_ will wipe out all the chips on that
> card, and may even put high voltages onto the bus lines and damage other
> cards.
>
> Therefore, do as suggested and get the unregulated PSU working first.
> Then take the cards (one at a time) and remove all socketed ICs. Make a
> diagram first, of course if you don't have the schematics/layout diagrams
> for that card. You'd better hope that the expensive/rare ICs (CPU, ROMs,
> RAM, LSI I/O chips) are socketed.
>
> Then put the (essentially bare) card in the backplane and check the
> outputs of the regulators on that card. Repeat for all the cards you
> have. Put the ICs back into a card before starting on the next one
> (unless you are a lot better organised than me!)
>
> Then, and only then do you put populated cards into the backplane and
> start testing logic functions.
>
> -tony
Received on Tue Sep 24 2002 - 21:31:00 BST