Repair a Malfunctioning LCD




Introduction: Repair a Malfunctioning LCD

This Instructable will show you how to repair a LCD that has dead rows and\or columns using a minimum of time and tools. The example shown here is a small LCD in a cordless telephone, but the same principle can be used in other devices as well.

Step 1: Tools Needed

This fix can be performed using a minimum of tools. You need only the tools necessary to disassemble the device (in this case only one screwdriver was necessary), a hot-air gun (a powerful hair dryer may work), and a pencil eraser.

Step 2: Disassembly

Disassemble the device to expose the LCD. Obviously, this step will vary by device. If you are having trouble getting your particular device apart, try Googleing "'yourdevicename' disassembly".

Step 3: Prep the Screen

Prepare the screen for repair by exposing the ribbon cable on the backside of the screen. In this phone, there is a plastic clip holding the LCD that must be temporarily removed. A plastic-coated paper clip is a handy for holding the LCD down while you work.

Step 4: Repair the Connections

Using LOW heat (you do not want to melt the ribbon or the solder on the board), slowly heat the ribbon cable where it is connected to the mainboard to soften the glue. At the same time, gently but firmly rub the connection strip with the pencil eraser.
1. Try to avoid directing too much hot air onto the LCD itself as this could damage it.
2. Apply enough heat to melt the glue holding the ribbon connection, but not enough to melt the cable itself.
3. If after the first try the problem is not resolved, try rubbing the connections down with something firmer. I repaired two identical phones using this method, and the second one required that I use the back of a plastic screwdriver to force down the connections.

Step 5: Results

With any luck, your results will be something like this. This repair, including disassembly, took approximately ten minutes to complete and the results are excellent; the screen is 100% functional again.

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162 Discussions

Fixed my old calculator! Just wanted to say thank you!

This made me squeal when it worked! I fixed an old treadmill computer from a machine I bought second-hand. There was a broken connection on the breadboard so I dunno if that work but we'll see! I didn't have a heat gun, blow dryer or clothes iron to use, but I made it work with the end of my hot glue gun. Thanks, God bless!

1 reply

No ribbon strip on my CMS921 just 8 pins that plug into the PCB. Please advise!! :-)

I just got my CM921 to work - so, carefully unplug or remove the lcd unit from the circuit board (8 pins i think) then separate the white board (same size as the lcd) from the back of the lcd display (it was glued on one side and i used a scalpel) the lcd will then flip over and you can see the ribbon, then follow the instructions above, return the lcd back down on top of the little white board as before and plug it back in...

Thanks for your post. You just saved me a £25 repair cost and a 1 week wait! Easy-peasey, broken to working in 10 minutes.

There may be a thin conductive rubber strip between the glass of the display & the board it is attached to. Over time this rubber can leak an insulating compound onto the interface connection that can, at times, be removed by removing the strip and gently rubbing it with a clean soft eraser. Be gentle as it can be fragile & easily damaged. This was an effective repair in the early days of these displays.

I did it ! and My old house phone is working again!Thank you so much!!!!

Has anyone done this with a TI-83+ graphing calculator or similar? I'm not sure which cable/part of the cable is likely not making contact? I'm missing a row of pixels. Any thoughts?

2 replies

Fix the cable just below J6, J4, & CON2 (you should be able to lift the LCD screen up off the board & pull the ribbon semi-straight to see the connections). There is a YouTube video with exact instructions for the TI-83+.

ps: I've tried a couple places but I'm not sure where is most likely and I'm afraid to be too aggressive with the heat gun until I'm certain.

Anyone tried to repair Sharp Oxford dictionary PW E550? The ribbon cable is held down by a piece of tape. Before I run out to buy a hot air gun would it work on tape?

1 reply

I just repaired a calculator that had the connectors held down by tape. I used a hairdryer on high heat and it did not mess up the tape.

Thank you!!! This totally worked. I just repaired my TI-36X Solar Calculator that had 2 semi-burnt out cells.

I used a hair dryer on the highest setting and the handle of a plastic makeup brush to rub the connectors as I heated them up. It did take about 5 minutes or so to get the right amount of heat and to find the exact contacts that were broken.

Thank you it work nicely

Very helpful, I fixed my kill a watts P4480, will try fix my 2001 Audi A4 dashboard center LCD display panel.

2 replies

Hey there, I'm dealing with the Audi a4 LCD issue as well, tho I haven't found any mention online of success with anything other than replacing the whole LCD panel (requiring tricky soldering & pricey screen)... Any success with this method? Or anyone out there have alternative solutions that've worked? (Ref to 2001 Audi a4 b5 inst cluster LCD multi info display =MID)
Thank in advance!

I tried few times, never get complete fix, just getting better, but once getting into summer, my work gone, give up