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Philips PM2423 Digital Multimeter


This must have been one of the last digital multimeters with nixies. It is a portable mains powered unit. The logic circuitry is TTL (transistor-transistor logic). Judging by the production dates on the ICs, it has been built in early 1974. The styling and design are quite different from the earlier Philips DVM's, such as the PM2433, the PM2420 and the PM2421. The meter has been made in Japan. The nixies are JRC brand, type B-5870ST. I bought this meter in March 2002.


A look at the digital circuit board. Analogue board taken out.

It is autoranging on the DC Volt and AC volt ranges. There are three ohms ranges: ohm, kOhm and MOhm. The display range has 3.5 digits.

Most of the circuitry is concentrated on two circuit boards: a digital circuit board containing all the TTL ICs, the range switches and the nixie tubes and an analogue circuit board containing opamps and a lot of trimpots.

manufacturer's name on circuit board

Made in Tokyo, Japan by Takeda Riken

When I studied the circuit boards, I found a familiar name on both of them: Takeda Riken. I knew they were a manufacturer of frequency counters, because I have a Takeda Riken counter with a nixie display. But I was surprised to see they apparently had been a supplier for Philips.

blurred digit

Display with one blurred digit.

This meter appeared to be in good condition, but it did have a few faults. One of the nixies showed a blur sometimes. This happened when it should read "1". Some measurements pointed out that the "1" output of the decoder/driver IC had an open circuit.
display working again

Display is working after repair

This IC had been replaced before. The original Toshiba TD3441AP had been replaced by a TI SN74141, production date 1973. I put an IC socket in its place in case it would ever fail again. After that, the display was OK, but most of the ranges were seriously out of callibration.

Regarding the number of trimpots, callibration is not something to do without a manual.

Fortunately, a year after I published this page, I received an email from someone who had the manual. He sent me a copy, so now it only takes the right time to make this meter swing again!

Copyright © 2002 by Onno's E-page         published 2002-04-01, last updated 2003-11-23