sick puppy  uni-t ut139c liqid in battery compartment - Page 1
Forum section: electronics / repair

author: kokodin
author_rank: Regular Contributor
timestamp: September 12, 2020, 08:11:25 pm
content: Hello there i recently discovered that my favorite work tool uni-t ut139c true rms multimeter has gave out a ghostthe way i discovered it was even wierdermultimeter was working fine, i taped with it on something to move it, very soft, but it gone blank and after trying to turn it on was beeping and blinkingafter opening battery compartment i discovered that most likely alkaline batteries has leaked. Batteries themeselves might have been there for 3-4 years already so i am amazed it still worked up untill now, but at least one of them spilled the juice all over the battery compartment and probably dameged something insidei cleaned the thing quite well with ipa, put new batteries in and it kind of back to life only it now go and show wierd thingsvolts DC -0.3 - -0.5Vvolts AC 0.004 probably fine but still interestingmV DC -573.3 mVmV AC - 0.00ohms auto range go crazy megaohms shows 0.000 other ranges OLtemperature probe works but shows around 1 to 4 degree celsius too much the lower the temperatore the bigger the erroramps without load shows 0 on all ranges , didn't tested morenvc worked contantly , now don't detect even close by wiresand a clamp shows -57 amps DC with no clampi have no idea which revision of the board is it but i can find that out probablyi know the case molding was made in 2013 based on the internal stamp but that might be missleadingi don't know what to check or how to clean it better, it doesn't seems to be missing anything or be dirty insideis it time for a new meter?

author: tunk
author_rank: Super Contributor
timestamp: September 12, 2020, 08:26:05 pm
content: Don't know if it makes any difference, but didyou clean the contacts on the rotary switch?

author: kokodin
author_rank: Regular Contributor
timestamp: September 13, 2020, 05:34:50 am
content: yes i did, multiple times in facti noticed there was some crystalisation buildup on negative battery connector so i desoldered it and cleaned that also along with every area of the board that had the white stuff on it, which wasn't much, mostly around desoldered contact.board looks clean but i am not sure is ipa disolves bases or if the crud that is there didn't creadte mini battery with metal on the traces. if yes i can't find it. but it must be after the fuses, taking them out makes no difference

author: kokodin
author_rank: Regular Contributor
timestamp: September 19, 2020, 11:36:52 am
content: i think i can close the topici got some free time on weekend so i thinkered around the meter some moresince it was alkaline damage and ipa don't work with that i go a bit crazy road with it and gave it a bath in water with citric acid (after desoldering the screen and beeper)i don't even know if the solution was strong or weak but it was visably bubbling around any white stuff that reapeared since last clean up, and took it all out in secunds. and i kept it inside for a bit longer brushing all around.later i gave it 2 water baths and standard "water damage" ipa cleanupafter cleanup and drying most of the ranges works normaly exept miliVolts where i still have negative runaway but now around 1mV/s starting from 0 slowing down around negative 30 and it counting 0.1 mV/s from there. who knows, when it get fully dry it may stop doing thatanyway shorting leads gives a stable readout around 0.00mV i say good enoughi don't use miliVolts at work so this might be fine even if it stays like that because this might be even static electricity or something i didn't clean or dry and does not affect reading accuracy that much