Recently, I decided to do something about the problem with my speedometer’s LCD screen. The bottom part of the screen and the edges of the screen are becoming more and more unreadable. There was something wrinkling on the LCD screen and this was causing the screen to become more difficult to read. While the speed could be read easily, the row of numbers below were becoming unreadable.
Believing that there was no hope of repairing the LCD screen, I decided to buy a used speedometer from Germany. This cost me quite a few coins because I needed one that was in KM/H instead of MPH. MPH ones were going for much less on Ebay.
After the replacement speedometer arrived and was fixed onto the bike, I took a closer look at the screen:
There was rough plasticky thing on top of the lens. A closer inspection revealed that this plasticky film was peeling off at some places. So with a tiny screwdriver, I started to gently peel off the plastic sheet. There was some glue attaching the plastic sheet onto the LCD glass. With that off, a bit of solvent and gentle rubbing, I was able to remove all the glue off the glass.
With the screen cleaned up, I thought I was good to go.
The reason why I wanted to repair the old LCD speedometer was because the odometer will show the correct mileage. I thought that with the plastic film removed, the LCD meter was good to go.
However, after I fitted the old LCD meter back on the bike and started it, I couldn’t see anything displayed on the screen! Looking from an angle, I could see faint images of the digital numbers but from all practical purposes, the screen was useless.
I did a quick search online to see what this plastic film was and it turned out that it was a polarizing film. Without it, the digital numerals could not be seen. So I went online and bought a sheet of polarizing film with adhesive on one side so that I can stick it on the LCD glass.
With this sheet, I started by trying to figure out the correct orientation for the polarizing screen. You can see the effect of the display as I rotated the sheet. What I didn’t take note at the time was the in addition to finding the rotation, flipping the polarizing plastic sheet also makes a difference. If you flip the film over, you will get a black background with white numerals. This can be quite cool. However, I decided to stick with the original display as I like the warm feel.
I thought I got it sorted after the first cut, but 3 things caused quite a bit of bewilderment and frustration.
The first thing was that I didn’t realise that the adhesive side was on the WRONG SIDE. Meaning, if I pasted the adhesive side onto the LCD screen the polarizing effect of the film was wrong. For some reason, I kept getting the answer that if I rotated the polarizing sheet that I just cut by 45 degrees, I would get the right orientation. The problem was that I kept flipping the sheet in order to stick it onto the LCD screen.
The second thing was that it was very difficult to stick the plastic screen properly onto the LCD glass. The usual problems of bubbles and dust caused a lot of headaches.
The third thing was that after sticking the plastic sheet onto the glass, the whole display turned black and I could barely make out the digital numerals.
So after I figured out that the adhesive was on the “incorrect” side, I contemplated sticking the adhesive side onto the inside of the plastic cover of the display instead. However, knowing that I could not get all the bubbles out, I decided to just cut a new piece just a bit wider and slipped it between the white frame and the LCD screen without removing the protective plastic sheet covering the adhesive. When the plastic cover was reinstalled, the force holding it onto the meter will hold the loose plastic film in place.
The display is just very slightly less clear than if I had removed the protective sheet from the polarizing film. However, for what’s its doing, the display is clear at daytime as well as night time. Very nice.