tracing out schematics

Has anyone got any useful tips for tracing out schematics? The SMPSU in this 'ere NCR Tower is toast, but it's a complex beastie as it's pretty huge and spread over two large boards. Is copying down component locations (but in their schematic form) to a sheet of paper the same sort of size as the PCB a good place to start? (Which can then be tweaked into a more sensible-looking schematic later) What about making a list of every component on the board and how many tracks leave it at each terminal, which can then be used for sanity checking? I'm not used to drawing out schematics for something this complex, so on smaller items I normally just muddle through somehow :) At least this one's only 2 layer... Aside: the PSU doesn't blow fuses, but is totally dead and doesn't even attempt to start. I found a dead 5W 10 ohm resistor (open circuit, no discolouration) in the live feed upstream of the bridge, which seemed like an odd component failure. I had a spare in the junk pile so replaced it, and that one immediately went the same way. The diodes in the bridge check out OK, the main filter caps aren't shorted, and the large chopper transistors (all 8 of them) seem healthy enough tested on a meter. Whether the filter caps are on the way out is another matter - no bulging/leakage though (I've got a homebrew ESR meter, but it's at the museum at the moment not at home) Startup for the machine is on the surface pretty complex; the switch on the front goes into the main backplane (multibus) and from there to who knows where. Then there are 12 low-power wires going between the backplane and the PSU (in addition to the main power lines) presumably for status monitoring / startup signal. Then there's going to be a lot of charging circuitry in the PSU for the system battery that keeps the memory alive when the mains power goes out... Hence the reason having done some obvious checks I really need to trace out the whole darn lot so I can see how the thing's even supposed to start up... :) cheers Jules -- PERSON 1: That's an awful gash on your forehead! How did you get it? PERSON 2: I bit myself. PERSON 1: How the hell did you manage to bite yourself on the forehead? PERSON 2: I stood on a chair.