Philips Multimeter PM2502 Teardown

[Spawn]

The postman delivered two nice analog multimeters today, these meters are couple years younger than me.

I got these from local auction website for a good price and both are in great shape, one of them is even like new. Meters date from 1975 and maintained really good, both are pretty accurate compared to my other DMM’s, see the photos and judge for yourself.

Uploaded the service manual here, for interested.


Two PM2502’s together:




Back, with battery cover removed, 2x 9v blocks and a 1.5v LR14, with these batteries it is rated to last for 1000 hours, there is also a common 1A glass fuse:




Back cover moved a side:




Huge capacitors, really nice feeling rotary switch, some unused holes for a different model I think and a “BUZZER” :




Front cover moved a side:




A big shunt, power bridge rectifier, precision wired resistor and some big resistors, a thumbwheel for ohms range and some squire test lead inputs:




Huge panel meter front:




And back, pins fall in holes on the PCB:

[T4P]

Big caps , big shunts , big bridge ... ole' 80's ... 

[Spawn]

Not 80's but 70's 

[Dan112123]

Not 80's but 70's 

And this is why it lasts forever

[free_electron]

And almost every single part made by philips themselves !

only the three  large 1% resistors are non-philips

[nctnico]

The big question is: does it work? The way the meter is connected through the spring loaded contacts seems like the typical 'lifetime limiter' Philips build into every product they ever made.

[Spawn]

The big question is: does it work? The way the meter is connected through the spring loaded contacts seems like the typical 'lifetime limiter' Philips build into every product they ever made.

Yes both meters are still working and pretty accurate too for their age

[PA4TIM]

They do last forever. I have the LCD version from the left one too, but the diplay is broken. Never found a replacement.
Calibration of this meters is not easy but the trick is to use a mirror.
The other anlog one is an active meter. It has autopolarity, is very accurte, has a high input resistance and eats batterys.
For me they are collectables, i use them now and then just for fun.

[AlphZeta]

It's interesting that they used 2 9V's for the high-Ohm range measurements. But I guess it's normal for a 100uA meter. For more sensitive meters, 2 9V's could support x100k range instead of just the x10K range.

[pkplex]

Just bought one of these, And it is my first analog meter.

It's more accurate than I thought it would be, and it is very nice to watch for peaks and what not.

I am learning how to do voltage / current regulation at the moment, and its nice to see a basic needle move up and down with current/voltage changes as I change pots/input/etc.