Casio VL-1 Display Cable

[Libra]

Hi at all

 

I have a problem on my new VL-1, with this flat cable for the display;

 

 

 

This cable is completely remove it from the p.c.b. and the same on the display.
I have try to repair or attach, but with a bad result. Where i can find a replacement flat cable?
Thanks at all,

Libra

[Null]

Good luck searching for the part on Ebay.

 

Or else you can try and repair it yourself.

 

 

Gary

[Display Name]

I'd just buy another one. They aren't that much on ebay.

[Libra]

Yes, i think is the right choice.

 

Thanks.

 

Libra

[CYBERYOGI =CO=Windler]

Do not discard it! This problem is very common (glue turns brittle), the fix simple but a bit wacky. Short answer: Mount the foil clable (on non-conductive side) with adhesive film into place (align correctly with PCB traces). Then install a foam rubber strip (window insulation) that keeps it pressed into place when the case is screwed back together. The complicated part is to cut and place the foam rubber in such a way that it evenly presses on all traces.

If this is not enough, here is the long answer (part of my next WarrantyVoid FAQ release).

fixing faulty LCDs:

Small LCD displays sometimes turn dim or segments fail by bad contacts. Most small LCDs are connected to the PCB by silicone rubber strips (known as Zebra connector) those contain flexible carbon contacts and squeeze against bare metal traces on the PCB and transparent contacts on the glass of the LCD. To fix them, take out the LCD, clean all the contact surfaces on silicone, glass and PCB with a Q-Tip with isopropanol. Then re-assemble the display. (Write down or make a digicam photo during dismantling when you are not sure about the correct part placement.)

Other LCDs (especially by Casio) are connected with a flimsy plastic foil cable, which carbon traces are glued to the contacts on PCB and LCD glass. These glue joints tear off very easy. A strip of adhesive window insulation foam rubber can be used to squeeze the foil cable back into place, which is sufficient to make the display work again when aligned properly. I read that they were originally heat-sealed in factory by pressing a hot metal bar with silicone rubber padding against the cable to melt the glue. The BONDMASTER MANUAL.pdf (from a Motorola pager repair machine) revealed the following parameters of different HSC foil cables.

forces & temperatures:

Planar = 50..70 psi at 140..150°C

Anisotropic = 50..80 psi at 150°C

Monosotropic = 70..90 psi at 160°C

"Planar" cables (pitch 0.3mm, oldest) are yellow-black.

"Anisotropic" cables (pitch 0.29mm, cheapest) are green-white or black-white.

"Monosotropic" cables (finest pitch 0.22mm) are yellowish, with thermoset adhesive.

The cable needs to be pressed into place during heating and cooling cycle, which in total may take about 1:45 minutes (recommended factory default of that machine). Depending on material, the heat can be between 140 and 160°C. Too hot or too much force can melt it or cut through the leads, so try lowest heat first. The thermoset glue of "Monosotropic" (yellow) cables may be impossible to re-melt and so needs to be replaced. Older cables may need even lower temperatures, so due to the risk of damage (the margin between gluing and destruction is small; also liquid crystals degrade from long heat exposure) generally only try heat where the foam rubber strip method fails. A suitable heat source is an adjustable SMD soldering station with temperature display. With soldering iron use thin cardboard to spread the heat and rub quickly back and forward; with hot air watch out that hot air gun temperature often starts much hotter and needs to stabilize; set air flow lowest to avoid damage to surrounding parts. If you don't own one, try a hairdryer + plastic bar (e.g. broad cable tie) to rub and press on. Unfortunately early Casio foil cables (tested in my PT-7) seem to be thermoset; they can not be reglued by heat. The Technical Guide For Casiotone from 1986 only mentions a shaped "soldering iron for heat sealing" with shaped "Heat Sealing Tip" attached and an "LCD Fixing Plate" as the work surface, but no hints about temperature or duration.

Particularly modern cheap LCD devices tend to use instead of Zebra connectors only very low grade foil cables, those to save a few cents often even lack protective coating on their carbon paint layer that makes them prone to oxidize or wear through when slightly missaligned and faithlessly crinkled into a too small case by pieceworkers. E.g. I got plenty of Chinese last generation LCD games of flimsy plastic those cables seem impossible to reattach. But even such devices appear to be often designed to support Zebra connectors (used in prototypes?), i.e. LCD and PCB contacts are still exactly above each other and have the same pin width. So an easy fix can be to replace it with a generic Zebra connector (the kind with contacts much narrower than on PCB) from scrapped old hardware. It can get difficult when the height doesn't match; theoretically the silicone rubber can be easily cut with any sharp tool (cutter, scissors), but in practise it is very difficult to cut straight enough to make all contacts touch with equal force, so in real life it may be better to change the PCB distance by keeping screws a little loose or pressfit it with more force to flatten the silicone strip. (I did this in a thermometer clock.)

When an old LCD does not show anything despite the hardware looks ok and you are not sure if the previous owner had dismantled it, then always check first if the polarization filter foil is missing. While with newer displays the filter is glued to the glass, with old ones it was a loose part that was usually only held in front of it by the case frame and could easily get lost during repair attempts; without polarization filter foil you will not see a picture (and the filter turned wrongways inverts the picture). A new filter may be available in camera or telescope stores; also cardboard 3D glasses with grey foil glasses (from a cinema) contain these foils or you may carefully peel it off from the display of a cheap or broken LCD clock or similar.