Editing Psion Organiser Capacitor Replacement Guide (section)

== Working out the values ==

Because no list exists, the values have to come from the parts themselves.

# '''Photograph the board before touching it''', square-on and in good light, so you can recover the original layout and polarity.
# '''Read the printing on each electrolytic.''' Forty-year-old parts are usually still legible: value in µF, working voltage, and often a temperature rating. Note the '''physical size''' too, because the replacement has to fit the same hole spacing and the same clearance under the case.
# '''Record polarity''' — both from the part and from the "+" mark on the silkscreen, which the Series 1 board does carry.
# '''Measure each part out of circuit''' with an ESR/capacitance meter. In-circuit readings on a board with an LM324 and several transistors across the rails are not trustworthy.
# '''Note the lead pitch''' before you order.

Build a table for your own machine as you go. If you do this, please consider contributing it — a verified Series 1 capacitor list does not currently exist anywhere public.