[WaveyDipole]

At last discussion I had changed the mains cable on the VTVM and replaced some capacitors. The meter seemed to be working but had some minor measurement and calibration issues.

My health has been suffering quite badly lately so work on this has been progressing a bit slowly, but when I got around to checking all the resistors, I found a handful of standard 1/4W carbon resistors that had drifted out of tolerance, including a couple of 22MΩ at the base of one of the valves, and two 150kΩ around the zero adjust that were reading 180kΩ, and two resistors around the AC Balance control that were also well adrift of tolerance. Some of these were replaced from what I already had in my parts bin, but others had to be ordered and I had to wait for them to arrive.

I also checked the resistance chains that form the divider networks for range selection. These all appear to be 1% tolerance and have some unusual and very specific values. These all seemed to be OK although one or two did seem rather close to being 1% adrift.

Powering the unit back up, it seems to be working a bit better. AC Balance is still quite close to the end of the adjustment, but no longer right at the limit. There is a small amount of leeway. On the resistance function, when set at one end to infinity, the pointer deflects to almost zero when the probes are shorted, so this is also behaving better.

Trying to remove the old resistors without damaging the tags can be a bit of a challenge. I snip the old component out, suck the solder of the tag and removed the leftover bits of wire. I managed nearly all of them just fine, except one. The last segment came away from the rest of the board. Can these be repaired with something like epoxy adhesive, or should they really be replaced?

I would also like to ask about those multi-turn pots with the three large bearings in the back that are used for the Zeroing controls. They are clean and there is no corrosion, but should they be lubricated with something? I used Servisol on one of the rotary controls as it was a bit stiff, but not sure what or whether to use anything on these bearings? Both controls are free running but feel quite loose for pots, although there is no lateral play in them. Perhaps they just have that kind of quality about them?