Dark Matter Invading Multimeter LCD :o - Page 1
Forum section: electronics / repair

author: Electro Detective
author_rank: Super Contributor
timestamp: December 08, 2019, 11:18:11 pm
content: This is straight out of a sci-fi showI have no idea what it is, the cause, or non-replacement/cheapskate remedial optionsI took it apart a while back to investigate, but it's actually in one of the layers(?) in the LCD itself,and casts its own shadow too within the layers,so cleaning, pressure jiggle, reflow or other magic LCD fixit isn't going to happen afaictIt began as a pixel-ish style dot a couple of years ago, and getting worse.So far it's not near any vital display data reading areas, and I could live with that,but betting it may get worse eventuallyIt's an -APPA 99 111- model,and poor 9v battery performance aside,plus the annoyance of having to wait a half hour for the Ohms/Resistance readings to settle/be accurate/cool off after a Low-Z test measurement on 240 volts AC,or other large voltage readings (a known/reported bug on these)this is a decent quality meter with loads of features,and it's CAL is spot on/or close/same with Flukesfwiw it's very Fluke 117-ish, but not quite in the 87 class, though the stock APPA leads are miles betterAFAICT this APPA 99 111, Benning MM 7-1 and Ideal 61-486 are the same item,not sure who actually makes and badges them.Looks like I may have to source a replacement display = good luck finding oneand or hoping it's an easy swap out, as I forgot what the mounting and connections are on thisAny clues, suggestions or SOL sympathies are welcome

author: MadTux
author_rank: Frequent Contributor
timestamp: December 09, 2019, 12:12:37 am
content: That's the LCD fluid leaking out or oxidizing to death.Probably because the glue that holds the 2 glass panels together is failing somewhere or was never really good at all.Will get worse over time until the complete display is dark.Another reason why I hate LCD displays. LED display FTW, VFD/CRT => OK, LCD => meh, OLED: utter crap

author: lowimpedance
author_rank: Super Contributor
timestamp: December 09, 2019, 01:06:48 am
content: I had a cheap 'Dick Smith' branded capacitance meter that did this. It just appeared and slowly got larger over a couple of years then retreated to a much smaller 'blob' over a similar time frame.It was not like the meter was subjected to any abuse or environmental extremes, it literally was just there when I got it out of the case to use.So I'm afraid you will have to live with it and hope it doesn't get any worse.

author: David Hess
author_rank: Super Contributor
timestamp: December 09, 2019, 01:09:47 am
content: Exposure to high temperature like sitting on the dashboard of a car in the sun can cause that.

author: DaJMasta
author_rank: Super Contributor
timestamp: December 09, 2019, 05:17:12 am
content: Also low temperature can do this kind of damage to LCDs not rated to extreme operating environments. Don't think it's reversible or repairable past just swapping out the screen, but it shouldn't progress all that quickly.

author: wraper
author_rank: Unknown
timestamp: December 09, 2019, 05:34:51 am
content: Seems more like delamination. Loosing airtight bond on the edge should cause black stuff expanding from the edge and be more solid black.

author: RobertPS
author_rank: Contributor
timestamp: December 09, 2019, 06:10:25 am
content: This oldie has been like this for at least two years. The lcd rot in the top left corner doesn't seem to grow very fast yet.

author: Electro Detective
author_rank: Super Contributor
timestamp: December 09, 2019, 10:25:10 am
content: Thanks for the repliesAFAIK the meter has not copped extremes like hot/cold/sunlight or drops,and lives in a re-purposed padded CD case mostly at room temperature.Random dud LCD I suppose, fingers crossed-The Blob-stays where it is