[Techman]

Cheers for all the advice and comments. The switches on this meter seem to be perfect and didn't need any cleaning, as I said before, I suspect that this meter failed early on in its life due to the incorrectly fitted capacitor, so hasn't had a lot of use to wear them out. I had to take it out of its case again to slightly readjust the DC voltage ranges - I think that pot is a little loose in its action and could really do with replacing to make it perfect.

I realised that the AC voltage adjustment is a bit more involved with the two adjusting pots interacting with one another, also there's low frequency and high frequency adjustments for this. I verified the approximate AC calibration of the DVM being used to calibrate against by comparison with a good analogue meter that I know is right and decided to adjust the AC voltage ranges at the low frequency settings using the mains as opposed to 100Hz as specified. The calibration voltages are, as they are in the DC adjustments, 1.90 volts and 190.0 volts. I'd forgotten how 'old school' these early DVMs are in that they're not linear. When set correctly at the top end of the range, they're then slightly out lower down in the range, and it's the same on both AC and DC ranges and there's only a single adjustment on DC, so just like a good old AVO then! However, this is good enough for most bench use.

As regards to the other meter that I mentioned, I found the original owners instruction manual for it. After looking through several drawers, I found it sandwiched in between a mig welder and a trolley jack manual - exactly where you'd expect it to be then! It's a better manual than I'd remembered and contains a circuit diagram and a parts list, but no information on calibration, so that'll involve a bit of guesswork. However, it didn't get that far as the meter went completely haywire after it had been switched on for a short while, so I've put it to one side for the time being and may start another thread regarding its possible fixing, that's if I think it's worth the trouble. Looking more closely at it and its manual, I've decided that it doesn't have any connection with Fluke after all, although it dates from around the same time as the Fluke meter under discussion in this thread.