Fluke 189 ghosting LCD - Page 1
Forum section: electronics / testgear

author: andyB2022
author_rank: Regular Contributor
timestamp: April 26, 2023, 03:40:07 pm
content: Hi, I know it's an old meter but anyone having same ghosting effect? Also the contrast is way worse than the 87V.Is there any way to get rid of the ghosting?

author: Fungus
author_rank: Super Contributor
timestamp: April 26, 2023, 09:23:11 pm
content: Quote from: andyB2022 on April 26, 2023, 03:40:07 pmYep.Pull it apart and clean the rubber connector that goes between the PCB and the screen, aka. "Zebra strip". It's usually pink.Many people use isopropyl alcohol but just rub it with something lint-free.Also clean the PCB contacts..

author: andyB2022
author_rank: Regular Contributor
timestamp: April 27, 2023, 03:39:18 pm
content: Tried that already. The PCB is very clean. I've seen someone on YouTube using silver conductive grease. I haven't touched the zebra with IPA as I'm afraid of burning it.

author: AVGresponding
author_rank: Super Contributor
timestamp: April 27, 2023, 05:53:10 pm
content: If you use conductive grease, it'll get everywhere and short things out, making the problem worse?The IPA won't damage the zebra strips, unless you leave them to soak in it overnight or something. They can also lose their springiness over time; if you can't increase the clamping force, you might have to fit new ones.

author: DavidAlfa
author_rank: Super Contributor
timestamp: April 27, 2023, 06:18:17 pm
content: Do not use there anything else than alcohol!Also read:https://www.eevblog.com/forum/testgear/poor-fluke-87v-dmm-lcd-segments-contrast/

author: Excavatoree
author_rank: Frequent Contributor
timestamp: April 27, 2023, 06:56:32 pm
content: Quote from: DavidAlfa on April 27, 2023, 06:18:17 pmI'm not asserting that the following is true. I'm just repeating it for evaluation. As another Youtuber says, "don't do what I do. Learn for yourself what you should do."I read someone, possibly on this forum, I can't remember, who said to NOT use isopropyl alcohol on these strips. This person asserted that the alcohol absorbed moisture from the air, and that moisture would damage the connector and or the contacts.Personally, I use a high quality contact cleaner without oil or any sort of metal preservative. I don't believe that alcohol isn't correct; I usually have contact cleaner, and I only have 70 percent IPA - which doesn't do well in my opinion.Of the meters I've had zebra strip connection problems, that solves over 90 percent of them. Some just require new strips. I've had some with the "carbon looking" contacts that never would work properly.

author: andyB2022
author_rank: Regular Contributor
timestamp: April 27, 2023, 07:11:32 pm
content: Quote from: DavidAlfa on April 27, 2023, 06:18:17 pmThanks for that! At least I know buying new strips won't solve the issue. I'll try to place somthing in the case that will press a bit harder on the LCD area, maybe that will solve it.Check the guy with the silver grease:

author: mwb1100
author_rank: Frequent Contributor
timestamp: April 27, 2023, 07:43:14 pm
content: Mr. ModemHead cleaned a zebra strip in this post:-http://mrmodemhead.com/blog/fluke-8x-faded-lcd/#more-1054The technique he advocates is to use QTips, one end wetted with IPA (90% or better) and roll the wet end along the contact edge to pickup debris, then roll the dry end to pick up IPA and debris. When dirty, discard the QTip and repeat with a fresh swab until the zebra strip is clean.Note that in his case, the zebra cleaning was done to fix an LCD that had missing segments, not ghosted segments. So for all I know it might need an actual replacement LCD. But a cleaning seems a good first step before getting replacement parts.

author: andyB2022
author_rank: Regular Contributor
timestamp: April 27, 2023, 07:51:28 pm
content: Thanks. Unfortunately, I can't afford to get the LCD in a worse condition, so I can't try everything...

author: DavidAlfa
author_rank: Super Contributor
timestamp: April 28, 2023, 03:52:15 am
content: A Quick cleaning with ipa won't damage anything!I've cleaned zebra strips several times, never had any issues.As said, it's just some rubbing, not soaking!

author: Fungus
author_rank: Super Contributor
timestamp: April 28, 2023, 05:43:14 am
content: Quote from: Excavatoree on April 27, 2023, 06:56:32 pmHow much "moisture" do think the strips would absorb in 2-3 seconds of cleaning compared to, say, 20 years of exposure to air?

author: Fungus
author_rank: Super Contributor
timestamp: April 28, 2023, 05:44:40 am
content: Quote from: andyB2022 on April 27, 2023, 03:39:18 pmPull the strips out of that holder, clean both sides with IPA, flip them around, put them back.

author: andyB2022
author_rank: Regular Contributor
timestamp: April 28, 2023, 06:47:23 am
content: The strips on the LCD side are stuck on it, and I'm afraid of damaging them while pealing them off. Do you guys recommend me to clean the glass on the LCD too? Where the strips make contact?As you see here (not my picture), the strips leave some residue on the LCD, but that residue means less material on the strip itself and a loss of material (higher pressure needed for the strips). It's just my theory. The whole idea is not to create a worse contrast on the LCD. Thank you!

author: giosif
author_rank: Frequent Contributor
timestamp: April 28, 2023, 11:13:22 am
content: I share your concern, as I usually do the same (i.e. worry of making things worse).However, what I've learned with help from people here on the forum is that, sometimes, you just need to take the risk.As they say "no risk, no reward".Also, for me, not taking risks can impede my learning.Just food for thought...And good luck, in case you decide to go ahead with the cleaning.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: April 29, 2023, 12:20:51 am
content: Quote from: andyB2022 on April 28, 2023, 06:47:23 amI forgot to mention that for almost every Fluke meter I've seen, I've never peeled the elastomeric connector from an LCD. I just leave it "attached" and clean the PCB and the other side. Maybe once in about 100 or so meters have I had to peel one off to replace the connectors when that didn't work. I've never seen any other model have the problem shown in the photo, EXCEPT the model 10,11 and 12 (and similar variants) The contacts on those LCDs are VERY fragile. I've cleaned the LCD contacts on other meters with no problem (but I don't recommend it, this was a meter with another ghosting problem that never went away, even with a new LCD and connectors) but I've damaged a model 10 LCD contact by looking at at it crosswise.