Repair a Malfunctioning LCD

Intro: 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.
Tips:
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.

Comments

[canterburyflyer]

I brought a DYMO Label Maker back to life. The most difficult thing was disassembly.
I Used a Hot AIr Rework device set at 250 Centigrade.
Nozzle about 2cm from the ribbon and as I heated I used the end of a paint brush carefully to massage the connection.
Before I thought that anything had been acheived I tested and found all characters were visable.
I must say thanks to you for giving me the impetus, courage,..huevos to attempt this.

[usachs]

I also brought a DYMO back to life. It fell from the table and the display was dead.
disassembling was not a big problem (Although when assembling, I had a spring over. Don't know where that was. Anyway, it works flawless).
In my case the ribbon was half detached. I took the pen solder bold and set it to 180 °C and slowly moved several times with medium pressure along the ribbon and pressed it onto the plate. I had to repeat this procedure 3-4 times until all pixels were working again.

[saadland]

I investigated my landline phone to repare its LCD according to this good tutorial, unfortunatly I found the cutted connection is not on the main PCB board but on the flat connector itself... and any heat applied (soldering tentative...) to the flat is going do destroid it completly ((
And there is not connecting pins on the LCD to be able to solder some wire directly to it.. ((
If anybody got some idea, thx in advance to share them

[l.poruba]

Instead of hot-air gun use hot melt adhesive (https://en.wikipedia.org/wiki/Hot-melt_adhesive) gun. Just use its hot spike, and you will be able to point precisely to the place you need a heat.

[Cabanas Keith]

I had a Natwest Card reader, where the screen was illegible and using this tip with my wife's hairdryer I got the card reader operational, many thanks !!!

[Instruct_Mo]

This is an awesome fix for my display. I followed all the steps but had to apply more heat than I thought.

Unfortunately, after two days the display started to lose some segments. What would other people recommend? Is this expected and should I have done something else other than heating and rubbing with an eraser?

Thanks.

[maarten.pieters80]

Many thanks for sharing the information on how to fix these displays! Worked out perfectly on a asus lcd poster from ages back which gave no screen at all and are not sold anymore to replace.

[robotlord2004]

nice, this saved my 5 year old calculator from the bin

[PaulP362]

Very good interesting piece. I am no way shape or form of an electronics junkie , but i am more like a jack of all trades and a master of none type. I have a dual power TS-100 hand held calculator where the second digit was pixelated I would say. I googled how to repair it and seen your story. I took my calculator apart and the back side is where that glue strip is at. I could not find my heat gun, thanks to having to move it for the Christmas tree setup. I used my Kitchen Propane stove front burner and waived it over it a few times. It took a few tries but I finally was able to get the dead pixel back. One good thing is the calculator was on so in between heat ups and eraser rubbings I could see my progress and man your fix really worked. Thanks fro the story. My favorite pocket calculator is fixed once again. I wish I would have taken before and after photos, but was too giddy to try your repair idea.

[coco.dozo]

Google offers no link as to how to open an AEG Voxtel D235 handset. After opening the battery compartment and removing batteries and the two Philips screws at the bottom, the upper half refuses to budge. Is there a method for opening the upper part, to access the LCD screen connector for repair? Any suggestions appreciated.

[xoundbox]

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

[IrishSnow35]

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!

[kyuholee]

Thank you, glue gun worked like a charm!

[Alden Tortem]

Actually we can repair even batteries using very simple method. Thank you KrzysztofC12 ! :)

[earn101]

Just repaired my Honeywell CMS921 thermostat display, fully working save £75+ Thanks!

[andy364]

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

[JamesI6]

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...

[MattM353]

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.

[ET60]

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.

[rorro33]

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