Author Topic: Fluke PM2525/PM2535 unobtainium LCD alternative  (Read 1870 times)

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Offline hackwellTopic starter

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Fluke PM2525/PM2535 unobtainium LCD alternative
« on: July 13, 2021, 08:16:40 pm »
Hi everyone,
I recently had the bargain to get two Fluke / Philips PM2525 bench mutilemeters off Ebay. For parts or repair that is.
I managed to fix both of them after a LM393 and two BRY39 replacement.
But I was left with one issue : a leaky LCD. These custom things are unobtainium of course , so I tried to figure out a way to get around this.
there are few attemps to do exactly that : https://www.eevblog.com/forum/repair/philips-pm2525-alternative-lcd-display/ and https://www.maximintegrated.com/en/design/technical-documents/app-notes/6/6315.html.
As I spend way too much time on aliexprees I found this : https://fr.aliexpress.com/item/32953790969.html?spm=a2g0s.9042311.0.0.69c66c37qZekH4
This one is perfect for the purpose (a little too small though) but guess what ? it does the job !







have look at my github for code and details : https://github.com/AKerambrun/PM2525-OLED-display
Now my meter is fully functionnal except the displayed 'NC' which means not calibrated. bugger!
if anyone knows how to generate 1000Vdc and 600Vac +- 0.05%... |O
« Last Edit: July 14, 2021, 05:05:52 pm by hackwell »
 
The following users thanked this post: edavid, coromonadalix, yuhar, ch_scr

Online coromonadalix

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Re: Fluke PM2525/PM2535 unobtainium LCD alternative
« Reply #1 on: July 13, 2021, 11:05:13 pm »
maybe using a signal generator with a signal transformer,  something with 32 ohms of more impedance and boosting you signal level that way and add a resistor load  like 20k ohms or more to slightly loads it without consuming too much at the primary ??
 

Offline bob91343

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Re: Fluke PM2525/PM2535 unobtainium LCD alternative
« Reply #2 on: July 14, 2021, 01:33:21 am »
Generating the voltage is no big deal.  But having it at .05% is another story.  Unless you need that range calibrated for your use, perhaps you can make the processor think you calibrated it.
 

Offline hackwellTopic starter

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Re: Fluke PM2525/PM2535 unobtainium LCD alternative
« Reply #3 on: July 14, 2021, 04:15:37 pm »
Yep you're right. I don't need this level of accuracy anyways. The voltage has to be within certain limits for the processor to accept the calibration though. Once I put th DMM toghether I'll give it a try and post the results. It seems that if only one range is not calibrated the uncal message is still displayed in all ranges leaving only 5 digits readings which is pretty annoying...
 

Offline tooki

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Re: Fluke PM2525/PM2535 unobtainium LCD alternative
« Reply #4 on: July 14, 2021, 04:47:54 pm »
That’s great work — please copy the images to attachments here on the forum so they won’t go missing in a few years when the image host goes out of business, or decides to charge money, or deletes your account or whatever.
 

Offline hackwellTopic starter

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Re: Fluke PM2525/PM2535 unobtainium LCD alternative
« Reply #5 on: July 14, 2021, 05:14:08 pm »
Done  8) I wonder why it didn't work eysterday...  I need to include them on github as well
 
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Offline TIG

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Re: Fluke PM2525/PM2535 unobtainium LCD alternative
« Reply #6 on: January 27, 2024, 01:02:52 pm »
 


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