Thanks Hal,
I'll start on the PS caps, but measure them all in-circuit first, and replace only bad ones. I think the PS board is plugged in, so should be easy to access.
My collection has a number of different variations, including original and newer type optical choppers, and a couple with the later ICL7650 chopper-stabilized op-amp. The one thing that's the same is they all use the original 5886 cathode follower input amp. I have plenty of spare 5886s, but as I recall, I've only had to replace one over the years. I remember having to replace the ICL7650 in one unit, the neon lamps in maybe a couple, and a number of bad caps in various circuit spots. I also have a couple with the flakey (literally) meter face problem that need restoration someday.
I figured on replacing all those headphone jacks with BNCs eventually, but for expedience I think I'll just make a phone jack to BNC adapter so I can scope the output signal for clues.
One other problem they seem to all have is deterioration of the foam cushions that suspend the input amplifier board. In the past I've made various foam arrangements to try out, and painstakingly adjusted everything to keep it properly centered in the mounts. More recently I did some experiments to see just how sensitive the board is to shock and vibration in my typical lab environment - it's about zero. I could rattle the board around in the empty mounts and tap on the 5886, with hardly any effect, so I decided to keep it simple and scrape out the old foam residue, then wedge some plastic tubing in to keep it from rattling around loose. It would likely be affected in a high vibration environment, but I don't have that, so no problem - I can't picture ever using these on my tractors.
Ed
