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To repair something, I had to disassemble it. Unfortunately, it had an LCD, and that used an elastomeric connector to connect to the LCD. Now I have an LCD, a PCB, and a spare elastomeric connector. I can occasionally get the LCD to work if I put them together, but it will not stay there, and the connection is very dodgy. Is there an easy fix?

enter image description here

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  • \$\begingroup\$ Did you get it back together? \$\endgroup\$ – Adam P Apr 2 '11 at 22:20
  • \$\begingroup\$ @Adam P, not yet, unfortunately. However, your answer was the most helpful. \$\endgroup\$ – Thomas O Apr 3 '11 at 12:00
  • \$\begingroup\$ I trying to fix a thermostat display, I'd thought the elastomer strip had conductive & insulated stripes in a pattern matching the LCD & board contacts. After many alignment tries making no difference, an ohmmeter showed very thin regularly spaced conductive & insulated stripes, so there's no set alignment. Also infers why more pressure made no difference. \$\endgroup\$ – CustomSarge May 23 '15 at 18:51
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As Toby Jaffey said in his post:

You need to ensure the strips are clean and dust free, line them up perfectly then maintain pressure. Be careful not to stretch or bend the strips while installing them as the contacts are often very small pitch.

This is probably the way to go. I would comment that in the picture it does not look like the contacts are very small pitch. I disagree with the other posters who have suggested using graphite to enhance the connection. I would not put graphite or any other conductive powder/substance on the pwb or connector.

In order for electrical contact to be made, pressure must be continuously applied to the LCD/elasto/PCB "sandwich". This is normally accomplished by the case, which is screwed together, pressing in on the structure from both sides.

The following procedure should work if you can pull it off. You might need help from a friend or some kind of jig...

  1. Sandwich the elastomeric connector between the LCD connector and the board pads. You will need to keep enough pressure on the sandwich to keep the connector from wiggling around.
  2. Screw the case back together while making sure the LCD/elasto/PCB sandwich doesn't come apart. This is assuming that you still have the case, and you will be reassembling it...
  3. Test it

Note: the LCD connector is not visually distinctive. Referring to the photo you have attached, I would guess that it is the translucent region at the bottom of the LCD module. You can just make out the "ghosted" strips which are possibly electrically conductive. Or maybe the clear strips are. You will figure it out. You probably could use an ohmmeter to test continuity if you are very careful and gentle. Anyway, the black squares on the connector edges are the conductive parts of the elasto connector, and should be lined up with the PCB pads and the conductive LCD "pads".

I once took apart an electronic guitar tuner which was having display problems, and to my great surprise encountered one of those elastomeric connectors. I had never seen one before. It totally freaked me out when it fell off and I could not see any adhesive or other fastening agent to reattach it with... but using the above procedure I put it back together and it's working, once again...

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No, there is no easy fix.

I worked on a product with an LCD and two 100+ pin zebra strips. It looked something like this:

Image Link Expired

In our design, there was a metal can with tabs poking through holes in the PCB. These tabs were bent to maintain pressure on the zebra strips.

This picture shows the idea:

enter image description here

You need to ensure the strips are clean and dust free, line them up perfectly then maintain pressure. Be careful not to stretch or bend the strips while installing them as the contacts are often very small pitch.

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  • \$\begingroup\$ Hmm, there are no metal tabs on mine :(. I can stick them together but they won't stay there long enough for me to screw the case back together. Before, the strip seemed to stick to the LCD, then it came off, now it won't go back on again. :( \$\endgroup\$ – Thomas O Mar 23 '11 at 0:28
  • \$\begingroup\$ @Thomas maybe you can help it stick? Tried to just adding a bit of scotch tape? \$\endgroup\$ – Earlz Mar 27 '11 at 21:44
  • \$\begingroup\$ @Earlz Problem is, it needs to be conductive. \$\endgroup\$ – Thomas O Mar 27 '11 at 22:59
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Once upon a time I took something apart one step too far. I had situation like that LCD. To put it back together, I used a very soft graphite pencil - 5B - to coat the contacts on both sides - LCD and PCB. It actually helped, though the end result was still dodgy, it was quite a bit less dodgy. This kind of pencil can be found at any artists' supply shop.

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  • \$\begingroup\$ Soft pencils (5B, or #1, can also be found at most office supply and stationery stores (e.g. Staples). \$\endgroup\$ – mctylr Mar 24 '11 at 22:14
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Same problems with LCD display on Beckman 3020 DMM's I used to repair 100's of the units this way,

Strip down the LCD Display, Clean up the actual LCD with a cotton bud soaked in Isopropanol, leave to dry, then get the elastomeric strip drop this in Isopropanol, leave this for not a long time say MAX five minutes, remove this carefully with miniature tweezers, place on a dry tissue for a time of one hour, place this back into the display, note clean up the Print on the module with cotton bud soaked also in Isopropanol leave to dry and replace all parts back, this will cure most problems, the Isopropanol actually expands most and leaving this to dry will shrink the unit back to nearly normal size, not to leave this strip in for too long as it might go out of shape, throughout the Beckman 3020 DMM they modified the Display unit to cure a known issue.

Philip 39 years in Electronics Testing

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Make sure both the PCB and the strips are clean of any debris - so that there are no gap irregularities. Also, you need to make sure you have the right amount of clamping pressure.

Also, you need to let the trapped micro air gap get squeezed out -- if you're lucky, the elastomeric strip will "seat" with time.

As for graphite -- graphite lubricating powder is available at home depot -- it's a dirty dusty mess, but takes the squeak out of door hinges -- and perhaps might work for this application, as suggested by others.

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I do a lot of these zebra strip reconnections and it is always problematic.

  1. The strips often leave silicone rubber debris on the transparent glass electrodes and on the PCB contacts. This must be removed with solvent and perhaps an eraser. Chlorinated solvent is good and an old typewriter eraser is good. Careful with the transparent contact and if the PCB ones are gold plated.

  2. Big problem is the zebra's PCB side takes an imprint of the bumps and valleys of the copper contacts on the G10 surface. These ridges and valleys won't go away unless they are sanded off with sandpaper.

  3. Third problem is that the elastomeric strip takes a compression set with time so when it goes back together it has less clamping force to overcome dust and irregularities.

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Isopropanol didn't work for me to clean the rubber remains of the zebra stripes on the LCD glass.. Instead I used Nitro thiner on a cotton bud and it worked like a charm!!!

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