Thanks Moe.
If there is a space for a battery configured for a battery the size of a tall pop can or beer can, with terminals on top, it would likely be a an "A" cell (still available).
For repairs, Other than potential switching differences, The Simpson 260 series 2 ( ftp://bama.sbc.edu/downloads/simpson/260/series2/series%202%20schematic.gif ) is still general enough to use for repairs of almost any other 20000 ohms per volt DC (1000 ohms pervolt AC meter). If your resistance values differ because of a different rating of the D'Asonval movement- they will be a ratio of what is there.
If it is actually a VTVM, all bets are off. I have a few references (magazines, books, other reference type materials) that illustrate some test equipment from the twenties through the fifties, but nothing indexed to find easily.
Otherwise, AG Tannenbaum, or http://www.w7fg.com/manuals.php are going to be where you might find a manual with that info.
:Looking for any info on Precision Apparatus Company VOM Model 844. Bought at local auction, wooden case in good shape. I need to know what batteries it takes, also a circuit diagram to help with minor repairs.
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:Thanks Moe.
It should be 4,5 volts and 45 volts.