Author Topic: PM2525 Multimeter Probe  (Read 8586 times)

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Offline MrAureliusR

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PM2525 Multimeter Probe
« on: August 31, 2013, 03:18:41 am »
Just curious, on the front of the Phillips/Fluke PM2525 there's a proprietary probe connector, and without this probe you can't do 4-wire resistance measurements, which is stupid I know. I'm trying to find out more info about it, to perhaps hack my own or find an original probe. I've been googling and I can't seem to find any info about it, the service manual only mentions that the part number is PM9264/01. There's one diagram showing the port being used during calibration, and it mentions (I think) that some of the pins use I2C??

Kind of confused. I think there's 9 or 10 pins on the port. My PM2525 is all packed up in a box as I'm moving on Sunday, but once I'm settled I can crack open the case and take a closer look at the port. Anyone who owns this machine, your input is greatly appreciated! There seems to be little to no information online about this probe. Googling PM9264 brings up a radiator fan motor...

Attached is a picture of the port.

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Amateur Radio operator VA3XMR
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alm

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Re: PM2525 Multimeter Probe
« Reply #1 on: August 31, 2013, 03:34:50 am »
The same probe is used in other Philips DMMs from that era. Some manuals contain the pinout. I got these two images from the PM2534 service manual.
 

Offline branadic

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Re: PM2525 Multimeter Probe
« Reply #2 on: August 31, 2013, 03:36:29 am »
I have a PM2534 and on this the connector is used for a temperatur probe, that was included when I received this multimeter.
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Offline PA4TIM

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Re: PM2525 Multimeter Probe
« Reply #3 on: August 31, 2013, 04:00:54 am »
Indeed probably for a temperature probe, I have a Philips , but the PM9203 RF probe used the same plug (but for a much older meter PM2421)
My  PM2517E has the same plug for a tempprobe


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Offline MrAureliusR

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Re: PM2525 Multimeter Probe
« Reply #4 on: August 31, 2013, 04:44:55 am »
I have a PM2534 and on this the connector is used for a temperatur probe, that was included when I received this multimeter.

It is used for both temperature probe and 4W resistance.

Some manuals contain the pinout. I got these two images from the PM2534 service manual.

Awesome, thanks! I'll try this configuration when I get the chance. I have a feeling it's probably as simple as that. I wonder what the I2C connection does. I recently received a copy of Vincent Himpe's Mastering the I2C Bus and so I've been trying to locate all the different I2C peripherals and chips that I own. It'll be interesting to probe the I2C connection... I can see in the service manual it's used for calibration but I'm sure there's more functionality than just that. I desperately want a Bus Pirate for times like these!

I'll probably go to my local electronics store, buy a few 8-pin DINs, and then figure it out using the above charts and/or process of elimination (AKA guessing) until I get it right. Then I was thinking about soldering four banana binding posts to the leads of the DIN connector, and heat shrinking all the cabling to have a 4-lead plug for 4W resistance. I also own a temperature probe (came with my UNI-T meter) which also has banana plugs, so if I can figure it out I'll add two differently coloured banana jacks (yellow or something) and attach them to the proper connections for temperature. It's possible (and actually now that I think about it, quite likely) that the temp probe connection is shared with the resistance leads. So maybe I'll just colour code the 4 leads, standard red/black, and then blue/green for the temp ones or something.

Does that sound like a plan?
« Last Edit: August 31, 2013, 04:46:28 am by MrAureliusR »
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Amateur Radio operator VA3XMR
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alm

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Re: PM2525 Multimeter Probe
« Reply #5 on: August 31, 2013, 04:58:44 am »
Note that the temperature probe (at least for the manual I looked at) is a Pt100 resistive probe. That meter is not going to work with a type K thermocouple as is often shipped with handheld multimeters and cheap thermometers.
 

Offline MrAureliusR

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Re: PM2525 Multimeter Probe
« Reply #6 on: August 31, 2013, 05:00:11 am »
Note that the temperature probe (at least for the manual I looked at) is a Pt100 resistive probe. That meter is not going to work with a type K thermocouple as is often shipped with handheld multimeters and cheap thermometers.

Yeah, I figured as much. From what I've read, it's not terribly difficult to build your own PT100 resistive probe though?
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Amateur Radio operator VA3XMR
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alm

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Re: PM2525 Multimeter Probe
« Reply #7 on: August 31, 2013, 05:21:56 am »
I've never built one, I suspect it involves a very thin platina wire. I would just buy one and fit the correct connector. For best accuracy you should use 4-wire connections, although you can also short the sense and source terminals at the connector at run two wires to the probe.
 

Offline MrAureliusR

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Re: PM2525 Multimeter Probe
« Reply #8 on: November 30, 2013, 02:07:48 pm »
Sorry to bump an old thread, but I've come back to needing 4-wire resistance measurements and this stupid proprietary plug is again a problem.  |O |O |O I still can't find any for sale on eBay or anywhere online -- does anyone who mentioned owning a similar model happen to have a probe they could sell?

I'm still thinking about just hacking one, but I'd rather try and get a real one first.

Thanks!!
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Offline robrenz

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Re: PM2525 Multimeter Probe
« Reply #9 on: November 30, 2013, 02:47:21 pm »
I am pretty sure that is just a standard 8 pin DIN connector. Readily available just about anywhere.

Offline MrAureliusR

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Re: PM2525 Multimeter Probe
« Reply #10 on: November 30, 2013, 05:55:03 pm »
I am pretty sure that is just a standard 8 pin DIN connector. Readily available just about anywhere.

Yeah, I know it's an 8-pin horseshoe DIN, I meant the original Fluke/Phillips cable that would have come with the meters of that era. I really can't find them anywhere.

On a side note, I just did a teardown of this multimeter and filmed it, it'll be up on YouTube sometime soon. It's a pretty neat meter inside. I even was able to dump the EPROM...

I ended up doing a rather quick'n'dirty hack of the DIN Probe socket. I happened to have an exact connector lying around (however it's not really a cable connector, more like a male panel mount) that fit (almost) perfectly in between the front panel plate and the socket when plugged in. I soldered wires to the solder cups, and put it all back together so I can easily hack into the connector.

The above pinouts seem to be correct, and the I2C bus mentioned in the service manual is on pins 5 and 6. Pin 5 seems to be SCL and pin 6 is SDA. The clock is about 70kHz. I'm going to see what I can do with my bus pirate, just curious as it's constantly repeating the same bytes over and over.

Update: Well the Bus Pirate can't seem to make heads or tails of it. I can see the data with my scope but the BP just reads 0x00 ACK 0x00 ACK over and over. Which is clearly not what's going on.
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Amateur Radio operator VA3XMR
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