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I recently disassembled my kitchen scale in an attempt to repair it. The LCD appears to have faded on the right side (which indicates the measurement type; g/ml/lb/oz). Although I managed to reassemble it, I was unable to determine the problem. The LCD is connected to the PCB using a conductive silicon zebra connector. I cleaned the conductive strip, the board, and the LCD glass with isopropyl alcohol but it made no difference. The fade appears to be gradual, so I’m going to guess that it’s not the board or the conductive strip.

LCD faded on right

Note: Should read '0 g', but reads L (no 'g').

Internal device photo

Image: LCD, backlight, board and conductive strip.

Question: Assuming it’s the actual LCD that has failed, what tends to cause them to fail? And how does it happen?

I appreciate that parts just fail over time, but as a learning experience, I’m curious why this happens as I’ve seen many LCDs fail in this way over the years.

Extra question: What do you search for and where do you search, if you wanted to find a replacement?

Nick Bolton
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  • I may be interested in this. So +1. Where I have troubles with an LCD display itself, it has has been with some calculators and some cell phones. There is a simple strip, not unlike what you show, along with a black rubbery block that the contacts press firmly against. Sometimes, I cannot get the display traces lined up entirely well enough apparently to get the display working correctly. In the cases I'm talking about the display was fine before I lifted the LCD away. And would not work fully upon replacing it exactly where I thought it was. There's more than my eye sees. I'd like to learn. – jonk Oct 02 '22 at 07:25
  • @jonk Russell McMahon's answer about aligning the zebra strip was quite interesting: https://electronics.stackexchange.com/a/269847/288848 – Nick Bolton Oct 02 '22 at 07:41
  • Perhaps of interest, I found that misaligning the zebra strip caused the LCD to not function at all (it was blank); assuming that it simply shorted connections out. – Nick Bolton Oct 02 '22 at 07:41
  • Thanks for those. I'll carefully look them over. Much appreciated! (I should add, though, that I've read similar stuff -- looking now -- that I still found myself with difficulty using the information I imagined I was gaining. So I still have some experience to gain here.) – jonk Oct 02 '22 at 08:23
  • Have you tried "changing" the supply voltage (just a little)? – Antonio51 Oct 02 '22 at 10:07
  • You know what… I wonder if this happened when I changed the battery? That said, there appears to be a regulator on the board but I’ll double check. – Nick Bolton Oct 02 '22 at 10:10

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