Capacitor values for original PET power supply?

----------Original Message: Date: Mon, 19 May 2008 00:21:23 -0700 From: Josh Dersch <derschjo at msu.edu> Subject: Capacitor values for original PET power supply? Picked up an original PET 2001-8 awhile back that's been heavily (and I do mean heavily) modified at various points in its history by someone with very odd design aesthetics. (See pic at http://yahozna.dyndns.org/scratch/hackedpet.jpg & http://yahozna.dyndns.org/scratch/hackedpet2.jpg). Various parts were hacked in and hot glued (!!) in place or just left to dangle. When I got it everything was loose inside. There's an Expandamem board and some homebrew job with some eproms and some hackery connected to the internal cassette port. There are various switches on the front and back that do who knows what. The keyboard & tape drive have been replaced with a different keyboard, alas. (I'll leave finding those two items for a later date...) And the power supply's capacitor has been replaced with some huge Sprague monstrosity larger than a pop can. Haven't even attempted to power it up since the power supply wiring's all hanging loose and taped together, but I'm afraid of that capacitor and I'd rather just return this thing to more or less "original spec" and remove all of this extra stuff. Anyone know what the original power supply capacitor was for this thing? I've found parts lists & schematics for the main PCB, video & voltage regulator but none of them appear to list this. (I'd also be interested in knowing the transformer specs & wiring, since I'm probably going to have to rewire that...) Thanks, Josh ----------Reply: Well, if it were mine I'd clean it up and figure out what's what and how to use it instead of returning it to the boring "original" spec. Don't know why you need to replace the cap or rewire the transformer, but FWIW the original cap is 23,000 at 15; presumably it was increased to deal with the increased current required by the extra boards. Don't know specs for the transformer but it and the wiring look stock as far as I can see aside FWIW, there should be 5 secondary terminals: 7 & 8 are the AC supply for the monitor, 5 is ground, and 4 & 6 are the two ends of the 8-0-8 secondary. The EPROMS may be interesting; there were a number of monitors, utilities etc. supplied in EPROMs, and some disk/tape software packages also used EPROMs for extra memory and copy protection; at least some of those switches will be for selecting the EPROM to use. Dump 'em if you can; they may be rare/useful. If the keyboard isn't an obvious hack, i.e. if it fits the case and has the PET graphics characters, it may be original; only the early models had the chiclet keys and integrated tape drive. mike m