Cost and who to adjust PM2525 - Page 1
Forum section: electronics / general

author: watchmaker
author_rank: Unknown
timestamp: September 20, 2024, 07:28:36 pm
content: I was given a very clean PM2525 that is just about perfect.All the measurements are within about 100 counts (9.920 VDC as opposed to 9.998) but show NC (Not Calibrated) after the reading.It lost its calibration data. I have no way to provide a single trigger signal to the DMM (required to complete the various adjustments), so I cannot adjust it myself.I am in the US. Who should I send it to and approx how much should I expect to pay? I need no certs, I just want it adjusted.THANKS!

author: J-R
author_rank: Super Contributor
timestamp: September 23, 2024, 12:31:08 am
content: Operations manual:https://doc.xdevs.com/doc/PHILIPS/PHILIPS%20PM%202525%20Operation.pdfService manual:https://doc.xdevs.com/doc/PHILIPS/PHILIPS%20PM%202525%20Service.pdfMy two cents is that getting this calibrated seems like a complete dead end. Even if you found a company that would do it, their price surely would be many hundreds of dollars if not close to a thousand due to the somewhat complex procedure. You have to do both a cold and hot calibration which involves placing the unit in a temperature controlled oven, there is the proprietary connector, and part of the procedure requires opening the unit and making physical adjustments.Even calibrating it yourself seems to be impossible since there is a page missing in the service manual and I don't see any reports of anyone successfully performing the procedure. On top of that, this DMM has weak points, such as the battery and the motorized selector. And it's only 21k counts (current is only 11k) with a 210k hi-res mode in some functions, with a 2,100/1,100 count high-speed mode. And the 1A/10A input is not fused.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: September 23, 2024, 10:26:59 am
content: It appears to be possible to calibrate this meter manually from the front panel and partially (one range at a time), and do the "cold" calibration only, pages 5-17 and 5-18 of the service manual describes the procedure. You would need an accurate source for each calibration point though or a stable adjustable source with a reference meter to get the right value. You don't need any "single trigger signals" if you do a manual calibration from the front panel. If you have a reference resistor, say 100kOhm, you could try to calibrate only 200k range and see what happens.CheersAlex

author: watchmaker
author_rank: Unknown
timestamp: September 23, 2024, 11:18:01 am
content: Quote from: Alex Nikitin on September 23, 2024, 10:26:59 amQuote from: J-R on September 23, 2024, 12:31:08 amThanks both. So pro adjustment is out.Alex, I will have to rread the manual again. There are several SM versions out there and I do have the complete one. But as I read it, onlu the PM 2535 has the ability to set the adjustment from the front panel while the PM2525 needs the probe or a computer to send the single trigger.RegardsDewey

author: J-R
author_rank: Super Contributor
timestamp: September 23, 2024, 05:16:16 pm
content: Can you post a link to the complete service manual?

author: watchmaker
author_rank: Unknown
timestamp: September 24, 2024, 01:08:43 am
content: Quote from: J-R on September 23, 2024, 05:16:16 pmI think I did this right.https://drive.google.com/file/d/1pcPl6TWvxbb6najI2avJB_ghP6DuiQQ1/view?usp=sharing

author: wn1fju
author_rank: Frequent Contributor
timestamp: September 25, 2024, 11:41:32 am
content: I have tried many times to calibrate my PM2525 and have never been successful. It has to be one of the worst calibration procedures ever for a piece of test equipment. But that's consistent with my opinion that the PM2525 is also one of the worst pieces of test equipment ever designed.My next attempt will be to place my PM2525 on an old tree stump in my back yard, aim my shotgun at it, and ....

author: watchmaker
author_rank: Unknown
timestamp: September 25, 2024, 11:54:58 am
content: I looked at the PM2521 SM. Now I understand why the 2525 uses the motor on the selector. It looks like the same selector on both and Phillips decided the motor was the way to automate that model. BUT, it does appear from the PM2521 SM that shorting pin 5 to pin 7 of the jack provides a trigger. I will try this when I have time.The other thing that is interesting is the logic levels are -10 and -5 volts.

author: watchmaker
author_rank: Unknown
timestamp: September 25, 2024, 12:15:50 pm
content: OK. Data hold can be set by connecting the center pin of the DIN jack to Pin 5 (Ground) of the jack. The display will show "Data Hold" and "Probe". The PM 2525 SM sez this signal is used for setting the adjustments in calibration mode. Will play later.

author: watchmaker
author_rank: Unknown
timestamp: September 25, 2024, 02:10:36 pm
content: Data Hold works. Still trying to calibrate.

author: watchmaker
author_rank: Unknown
timestamp: September 27, 2024, 06:34:30 pm
content: Quote from: wn1fju on September 25, 2024, 11:41:32 amThis adjustment sequence works. Sadly the unit I want to bring online seems to have an EPROM issue; display shows adjustment success but it is not saved on reset. Works on my good one.Push reset and cal at the same, release reset and then cal to enter cal mode.Also, I found quite by accident that when the meter is turned off (via my bench power strip) it stays off when I repower the bench. UNTIL I push my single trigger switch, which is connected to the center pin and pin 7 of the "Din" jack.For my use, this is very convenient since I do not always want that meter on when I turn on my bench power.