All those symptoms add up to a high probability of a bad lead,
probably the black one. Hold the plugs and pull on the wire. If you
see any stretching of the insulation, that's where the break is at.
The old Simpson meters (c. 1960) weren't particulaly accurate. Their
accuracy was expressed as "Percent of full scale."
Thus, if you measured a nominal 10 volts on the 100 volt scale, your reading
could be up to 1 volt in error with a 1% full scale accuracy meter. Use a
2% meter (Most Simpsons were 2%), and you can be off by 20% on a 10 volt
measurement on the wrong scale.
I didn't take that seriously until I had to make a LOT of measurements on
microwave diodes and found that my "simpson" meter readings were so
inaccurate as to make my data worthless.
You can pick up a digital meter from Harbor Freight for less than $5 that's
more accurate than any "analog" meter.
You might want to keep the old meter around as a curiosity (or in case you
fear that WWIII will fry everything electronics) but except for "fun"
purposes, they aren't worth fixing.
We used a lot of them for maintenance on various pieces of government
equipment. They were accurate enough for what we were using them for.
Filiment voltage...6.2v...close enough for me...anode voltage 150v...close
enough for government work :)
Like many old timers, I cut my teeth on analog meters, and I still prefer
them to digital meters. When I'm working on house wiring, I usually use some
digital clamp on thing made for electricians. But when I'm working on my
rf/audio gear, I'll take the analog meter any day.
RS never sold a meter worth fixing. Just chuck it if you can find a
problem inside like worn out battery or fuse. I saw a digital meter with
clamp on AC current probe for 9.99 in a local store.
My meters are Fluke, Amprobe, and Simpson.
RS hasn't sold much of *anything* worth fixing for a very long time. I
stopped buying Radio Shack products years ago because I got tired of them
breaking or otherwise going bad. A long time ago Made In Japan products used
to have a bad reputation (ok, I'm dating myself). Now it's the made in China
stuff, which is just about everything in Radio Shack, is even worse.
I took the thing apart, and found two pots I need to check. I have a
half-dozen meters already, so I think I'll put this back on a shelf with the
rest of the stuff I don't have time to sort through.
With chinese stuff, it depends on the engineering. The engineering of the
product and of the manufacturing process is rarely chinese.
Radio shack like the lipstickonapig approach. The crappiest products, but
with a pretty case.
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