Re: Avo 7 meter - no voltage reading
They juggled with the serial numbers sometimes; reversing the date and instrument number.
7945-23404 is actually: Model 7, September 1945, Meter number 23404.
David has posted a link to a PDF doc, above, the last page of which has a circuit diagram. (Yours is a Mk1 meter)
A peculiarity of Model 7 is that the needle zeroing is carried out with the meter set to a DC range. When putting the meter away it is recommended not to leave the meter set to an AC range- as a trickle current is taken from the 1.5v cell to bias the rectifier for accuracy on low voltage AC readings. Admittedly it is a very small current.
Dave
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