Re: repairing a multimeter: PM2412

Look at virtually any VOM schematic.  The resistors should all
be in simple proportions for the different ranges (ie: 9 ohms,
90 ohms, 900 ohms) and as accurate as possible -- 1% or better.
A schematic might diagram how the switch works, but won't
necessarily make tracing the connections to it any clearer.
If you're really dealing with a VOM -- not a TVM or VTVM, etc.
there won't be any extraneous circuitry to confuse you.  Only
the ohms ranges need the battery.

peter_dingemans@xxxxxxxxxxx wrote: 
Mike,

I've recently repaired an AVO8 and a Russian 'TSE' 4313. In both cases
I needed schematics (how else to identify those burned out resistors).

The PM2412 had also some defect resistors (severely damaged by a
leaking battery), so that's why the need for schematics and/or service
manual.

IMHO, multimeters are difficult to service: lots of tracing, double
checking, how do the wires run, how do the switches work. Hmm, even
trying to understand how it works takes a few hours studying the
schematic for me ;-)

Grtz,

Peter.

.

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