Philips PM2528 - Page 1
Forum section: electronics / testgear

author: stcoso
author_rank: Regular Contributor
timestamp: May 14, 2017, 09:38:30 am
content: Hi guys i've recently bought this old but very nice benchtop multimeter for a few bucks. It powers up but some strange and obscure messages appear on the LCD. Playing around with the buttons i'm able to make some of the range relays switch (actually only the current range relays) but i can't get any measurement...I know it's a long shot but i think that may worth the effort of repairing itSo... i've opened it and checked the power supply and all seems to be fine...Any hint?PS i've never seen anything built like this.. it's a thing of beauty. They've put so much care into designing and bulding this thing

author: markce
author_rank: Regular Contributor
timestamp: July 20, 2017, 12:20:34 pm
content: Are you sure it's a Philips PM2528?I only know that one with LED display...

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 20, 2017, 02:19:02 pm
content: Quote from: markce on July 20, 2017, 12:20:34 pmExactly, I have one at home and it's LED.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 20, 2017, 11:29:00 pm
content: thats a nice meter, but there a ton of trimpots in there, relays toosome inside look :http://www.gloeidraad.nl/radioforum/index.php?id=146115

author: markce
author_rank: Regular Contributor
timestamp: July 21, 2017, 03:54:21 pm
content: Yep, lots of trimpots, so you can calibrate it with very simple equipment.The large HP LED's are very convenient. The meter powers on in an instant. Mine is from 1982. I still use it one on a daiyly basis.

author: markce
author_rank: Regular Contributor
timestamp: July 28, 2017, 05:32:52 pm
content: The PM2528, if that's what it is, has a serial interface to the display (shift registers). On startup it displays whatever is in the registers, looks a lot like 'ABBA' text on my meter. On mine it's always the same pattern, but its different on another meter.I guess your meter does not clear the display, so does not finish initialization. It has a 8031 processor control system with its firmware in old EPROMs. Unless you can measure on the processor bus, and given power supply is ok, I would check clock running end EPROM checksum next.

author: markce
author_rank: Regular Contributor
timestamp: August 01, 2017, 10:06:43 pm
content: .

author: stcoso
author_rank: Regular Contributor
timestamp: September 18, 2017, 09:24:37 am
content: I notice only now the reply ! So i'm gonna take some pictures..Messing around i've noticed that one of the IC (a uln2003) was inserted in its socket with one leg bent up ... is it normal?

author: markce
author_rank: Regular Contributor
timestamp: September 18, 2017, 07:50:18 pm
content: Depends which ULN2003 you were looking at. The one on the main board is fully used. The one on the display board is only used partly, lifting one of the unused pins is harmless.

author: stcoso
author_rank: Regular Contributor
timestamp: September 23, 2017, 10:20:47 am
content: It's pin1 of the uln2003 on the main board

author: markce
author_rank: Regular Contributor
timestamp: September 23, 2017, 04:41:21 pm
content: Pin 1 is an input, pin16 is its driver output, which connects to the K1603 relay. The "20mA Ac" and "20mA Dc" ranges will not work with pin 1 disconnected.