repairing a multimeter: PM2412
 

G'day everyone,

I'm trying to repair a Philips Bench multimeter (VOM), the PM2412, but
can't get any further without the schematic. Does anyone have one
available, or know where to find it online? Been looking several
evenings now, but can't seem to find anything on this meter (or its
relatives).

If anyone has information on this meter, it would be greatly
appreciated!

Grtz,

Peter Dingemans
The Netherlands.

repairing a multimeter: PM2412
 

What's the problem? A VOM should be pretty trivial to
service without a schematic.

wrote:
G'day everyone,

I'm trying to repair a Philips Bench multimeter (VOM), the PM2412, but
can't get any further without the schematic. Does anyone have one
available, or know where to find it online? Been looking several
evenings now, but can't seem to find anything on this meter (or its
relatives).

If anyone has information on this meter, it would be greatly
appreciated!

Grtz,

Peter Dingemans
The Netherlands.

repairing a multimeter: PM2412
 

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.

repairing a multimeter: PM2412
 

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.

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.

repairing a multimeter: PM2412
 

Hello Mike,

I've found a schematic and the meter is repaired. A few resistors in
the resistance range were damaged by battery acid and have been
replaced. It's now fully operational again.

However, a generic schematic wouldn't have been of much help here, at
least not to me; someone more experienced might get by, though.

BTW, there's quite some extra circuitry in the meter, to prevent damage
from overvoltage/current. 3 batteries (9V for the resistance, 9V for
the protection circuit and 1.5V (mono) for the lower resistance
ranges).

Anyway, thanks for the tips and help in getting this meter fixed.

Grtz,

Peter.

repairing a multimeter: PM2412
 

Hello Mike,

I've found a schematic and the meter is repaired. A few resistors in
the resistance range were damaged by battery acid and have been
replaced. It's now fully operational again.

However, a generic schematic wouldn't have been of much help here, at
least not to me; someone more experienced might get by, though.

BTW, there's quite some extra circuitry in the meter, to prevent damage
from overvoltage/current. 3 batteries (9V for the resistance, 9V for
the protection circuit and 1.5V (mono) for the lower resistance
ranges).

Anyway, thanks for the tips and help in getting this meter fixed.

Grtz,

Peter.

repairing a multimeter: PM2412
 

wrote in message
oups.com...


I've found a schematic and the meter is repaired. A few resistors in
the resistance range were damaged by battery acid and have been
replaced. It's now fully operational again.

However, a generic schematic wouldn't have been of much help here, at
least not to me; someone more experienced might get by, though.

I don't doubt it. Philips stuff, esp. back in the days of tubes, was
bizarrely complex - mad scientist stuff.