EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: hackwell on July 13, 2021, 08:16:40 pm
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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/ (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. (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 (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 !
(https://i.postimg.cc/c6sX1nKL/20210711-175534.jpg) (https://postimg.cc/c6sX1nKL)
(https://i.postimg.cc/d7YGWbrV/20210711-175459.jpg) (https://postimg.cc/d7YGWbrV)
(https://i.postimg.cc/bdJkFHDk/20210713-193834.jpg) (https://postimg.cc/bdJkFHDk)
have look at my github for code and details : https://github.com/AKerambrun/PM2525-OLED-display (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
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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 ??
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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.
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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...
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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.
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Done 8) I wonder why it didn't work eysterday... I need to include them on github as well
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This post saved my Philips PM2535, see my post at https://www.eevblog.com/forum/repair/unobtainium-philips-pm2525-pm2534-and-pm2535-lcd-replacement/ (https://www.eevblog.com/forum/repair/unobtainium-philips-pm2525-pm2534-and-pm2535-lcd-replacement/). Many thanks!