[Test-Equipment] Simpson 260

[Steve Byan]

I have what I think is a Simpson 260 "series 1" VOM. It doesn't say 
anything other than "model 260" on it, and its differs in quite a few 
features from to the Simpson 260 series 7 according to the series 7 
Operator's Manual that I have. It has a voltage range of up to 1000V on 
the main input jack and 5000V on the high-voltage jack. It's completely 
hand-wired (no PC board) and uses a compartmented bakelite chassis to 
house the ranging resistors. It uses a single D cell and four AA cells 
for resistance measurements. It has a couple of inspection stamps 
inside and what might be a date stamp of "128  54" (day 128 of year 
1954?).

This unit reads about 20% low on the 2.5V and 10V ranges (and probably 
the others, though I haven't tested them). The schematic on my series 7 
manual shows a couple of pots that look like calibration adjustments, 
but my meter doesn't have any pots. It has a couple of hand-wound 
resistors that are easily accessible; the rest of the components are 
buried in the bakelite chassis, and I can't figure out a way to get the 
chassis separated from the front panel - there's not enough slack in 
the wiring to pull the chassis and range switch away from the front 
panel.

So my question is: how do I re-calibrate this beast? Anyone have the 
calibration instructions for a Simpson 260 "series 1"? Am I supposed to 
re-wind the two resistors that are accessible?

Is anyone interested in trading a more recent vintage 260 for this one?

Regards,
-Steve
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Steve Byan <stevebyan at mac.com>
Littleton, MA