Uni-T 61E Screen is shot.... - Page 1
Forum section: electronics / repair

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 04, 2015, 04:09:09 pm
content: So I just ordered this meter and unfortunately I kind find any other american sellers online to replace it...I opened the meter to add a back light and replace the fuse and fuse holders with proper 1000v buss man cermaic's, also replace some PTC's with higher quality ones. All these mods worked out great, made the meter much better!Unfourtantelly whie cleaning up some flux I accidently got Acetone all over the LCD, put it back together LCD, worked but it was all bubbled... so next I tried wet sanding the surface with 400 gritt to 2500 gritt wet/dry paper. Next I cleaned the entire thing with alcohol. Let it dry, sit over night. Now segment of the digits and Bar graph are not working.....Since this screen is a 22,000 count screen does anyone know a part number, for it?? My next option if i want a comperable meter from the US is 130 for a Uni-T71D which is nice but still needs some work in my opinion I would rather just cheaply replace my LCD!

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 04, 2015, 04:10:53 pm
content: BTW zebra stripes have been cleaned with 90% alcohol and scotch tape many times

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 04, 2015, 07:25:26 pm
content: I have tried every way to get more pressure on the conductive foam!!! exact segments are dead, already ordered a new meter UT71D, like to fix this one though! Would conductive ink pin on the zebra stripes help if the sanding maybe screwed the stripes up somehow, I didnt sand that side but this definately does not look like an issues with the PCB more like a connectivity problem.Can someone explain how the foam insert acually works and keeps traces seperate? what id I just used black IC foam?

author: Marc M.
author_rank: Regular Contributor
timestamp: September 06, 2015, 04:06:08 am
content: Quote from: rwgast_lowlevellogicdesin on September 04, 2015, 07:25:26 pmBy 'foam insert' are you referring again to the Zebra strip? If yes, then no, you can't use conductive foam because it isn't that conductive and provides no isolated channels thru the material to pass the various voltages to the display. Zebra strips are simply alternating layers of conductive & non-conducting rubber IlIlIlIlIlIlIlIlI . It's simply sandwiched between the pcb and the contacts on the LCD glass. The spacing of the contacts in relation to the spacing of the Zebra strip work out so that exact alignment of the strip isn't critical (e.g. the pitch of the strip is usually much finer than the pitch of the contacts). What is important is the distance between the PCB and the LCD stay consistent across the contact area so even pressure is applied across the entire face. The Zebra strip also has to be the correct thickness for the space between PCB/LCD. A bit too thin and it won't press hard enough against the pcb/lcd to make reliable connections. A little too thick and it will get compressed too much, distorting it and again causing connection issues. Needless to say, any sort of distortion to the strip can cause intermittent connection issues.The only thing I have ever done to clean Zebra strips/pcbs/lcds is alcohol (92%). I wouldn't ever consider using Acetone to clean a pcb that is installed in the product because it attacks a lot of plastics/rubbers/paints. Most the Zebra strips I've dealt with felt like they were silicone based. I think silicone swells a bit when exposed to Acetone which would then cause it to distort when installed. If that is the case then replacement is the only option. You might try pulling it back apart and re-install the Zebra strip with it flipped horizontally then try again flipping it vertically to see if changing orientation has any impact on which segments function. Simply pushing on the front of the display may affect which ones work.Silver Ink Pen? Sorry, not really an option here. Your issues are mechanical in nature, no problems with the strips ability to conduct. You can easily measure across a Zebra strip with your meter and that will also give you an idea how fine the pitch is. Trying to paint new tracks on it would be like trying to paint the Mona Lisa with a 4" house painter's brush. Also, the silver inks I've used over the years are really paints and they dry pretty thick again creating more mechanical issues.

author: mos6502
author_rank: Frequent Contributor
timestamp: September 07, 2015, 05:35:26 pm
content: You do have one option left: take the LCD signals off of the PCB, feed them to a Microcontroller, and use that to drive your own display. Something like a 128x32 LCD or even an OLED should work.