I can't remember exactly where I downloaded the PDF Altair Manuals from, but I am pretty sure they were for the 8800/8800a and not the 8800B. If I find the CD I burned them to I'll check to see if I saved the URL and if there are 8800B manuals there. If so, I'll be happy to point you to the site or mail you a copy of the PDFs if the site is gone. In the meantime, I would suggest checking out either www.altairmanuals.com or http://njcc.com/~hjohnson/s100.html. Both sites will sell you a copy of the 8800B manuals for a reasonable price. Good luck! Erik Klein www.vintage-computer.com/vcforum (The Vintage Computer Forum) -----Original Message----- From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org] On Behalf Of Steve Leach Sent: Sunday, May 25, 2003 7:06 PM To: cctalk(a)classiccmp.org Subject: Re: !HELP!! ALTAIR BLEW SMOKE!!! Well, I must say I'm rather amazed at how quickly I got a response. Within an hour of my post, two individuals (Steve Thatcher and Scott LaBombard) both provided the information on the tantalum cap, and I found the parts at DigiKey. Thanks guys! I'm so glad to see some hope at getting the Altair back up and running. When it sizzled popped and smoked, it was like an old friend had died. If you could humor my electronic ignorance, what exactly IS a tantalum cap and how does it differ from a normal capacitor? I was never before aware that there could be more to a capacitor than plates (or foil) and an electrolyte. How can a capacitor have a polarity? Another question, does anyone know where I can find a replacement for the two position front panel switches on the Altair which are marked "AMERICAN U.S.A ST1-1" These are 2 pos 3 contact switches, and I've not been able to find anything exactly the same dimensions. I am hoping that this is some standard switch and I'm just not aware of it :-) Also, I've come across rumers of Altair manuals online in PDF format. Does anyone know where I could find such a thing? I'm sure I'll have more questions once I get the poor machine put back together and start trying to figure out the disk drives and controllers :-) The machine was stored for over seven years in a barn wrapped in plastic bags (not my decision! Don't burn me at the stake!) I wonder how many more surprises I'm in for?

A capactior is actually 2 plates separated by an insulator, called the dielectric. In the case of something like a mylar capacitor (or one of the other 'plastic' ones), the dielectric is a thin piece of mylar with the metal films (for the plates) deposited on the 2 sides. The whole thing is then rolled up to get it into a small enough package. In an electrolytic capacitor (there are 2 common types, aluminium and tantalum), the 2 plates are a metal plate and the electrolyte. The dielectric is an oxide film on the surface of the plate. This film is very thin, which meance you can get a large capacitance in a small package _but_ it will also redisolve into the electrolyte, especially if the capacitor is wired up backwards. That's why these units are polarised. Connect them backwards and the dielectric disolves, the capacitor becomes a short circuit. If enough current can then flow, the electrolyte might even boil with the consequent explosion of the can! Electrolytic caps fail in 2 main ways. Firstly the dielectric might redisolve in the electrolyte, causing a short. Secondly the electrolyte can evapourate ('dry up'), inceeasing the effective series resistance (ESR) of the capacitor. -tony