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| UNI-T UT61E Won't hold calibration |
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| Danielfs78:
Hi, First of all, forgive my English, i'm not a native speaker. I'm starting to play with electronics (mostly arduino stuff) as a hobby, and i have an UT61E, bought a couple of years ago that just started reading lower voltage values. I almost have no free time nowadays, so since i bought it i must have used it no more than 50 times or so. It justs sits on my bench. Recently, i was building another variable power supply and the 61E was reading about half volt lower than the 5 volts the PSU was outputting. I thought that the PSU was falty, but the next day i tried my old, cheap multimeter and the PSU was spot on. Since then i did more tests (with a new battery, other multimeters and a chinese voltage reference) and the 61E was the problem. The problem also occur when measuring AC voltages, what supposed to be 126V was reading 106V. I read about calibrating it and i did. It needed only a tiny movement on VR1 to fix DC and AC measurings (i did not try the rest of it's functions). For a few moments it was right again, but the next morning the error showed up again, and that's about the same offset as before. Does anyone knows what i should do to fix it? I read about checking the resistor array or replacing the voltage reference, but could not find anything i could follow. Thank you all in advance. Daniel |
| rsjsouza:
Olá Daniel, I think in your case it will be better to replace the multiturn trimmer with a better quality one. There is a thread where people discuss replacing it, check it out: https://www.eevblog.com/forum/testgear/replace-dc-calibration-potentiometer-on-ut61e/ |
| Danielfs78:
Thank you very much! I'll try that! |
| newbrain:
This is what happened to my UNI-T 61D. The 61E schematics shows a single resistor while the 61D had four, but the symptoms are similar: worth a check. |
| rsjsouza:
--- Quote from: newbrain on March 27, 2018, 02:32:09 pm ---This is what happened to my UNI-T 61D. The 61E schematics shows a single resistor while the 61D had four, but the symptoms are similar: worth a check. --- End quote --- Thanks for sharing this. Yes, the UT-61E has a single large resistor network as the divider. If that goes bad, a full replacement will be needed (although I fixed a 8060A years ago that had a bad joint between the PCB pin and the pad on the network itself). In the OP's case, though, it seems the pot went bad - a light touch on it seems to bring the meter back to the correct measurement. That or a resistor is constantly drifting... |
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