Re: What are these things called?, Newbie question...

Zebra strip is a little rectangular strip of rubber, with lots of conductors perpendicular to the long axis. You lay it down across a set of contacts on the PC board (with spacing much greater than the conductor spacing in the zebra strip) and press the LCD into it. The idea is that you'll pick up at least one zebra-strip conductor on the PCB and LCD, and have at least one insulating layer between contacts. You can't really extend it at all.

The flat strip stuff is a replacement for ribbon cable. It has a much wider conductor spacing than zebra strip and each conductor goes to a pin on the relevant connector. I don't know what it's called beyond the brand names (flex cable?).

I poke around in sci.electronics.misc a lot just out of interest. The other crossposted newsgroups I generally don't. See you 'round comp.cad.solidworks Wayne.

'Sporky'

Wayne Tiffany wrote:

I once had a pile of fluke multimeters, and the assignment of combining the broken ones to make REALLY broken ones and a few working ones... These have a zebra strip in them that is a full inch long by two inches wide. And if you've shifted yours, if you've taken it out to look at it etc... then good luck getting it to work again. They use them because the contacts on the lcd are not solderable (not to mention being transparent and therefore nearly invisible). So you can't just replace them with wires. And the placement tolerance on them is very exact. As in you have to place it accurately to within a few thousandths of an inch, or you will have contacts being touched by two conductors, or two contacts being touched by one conductor... and you have to be this accurate on both ends. Not once did I manage it with the Flukes, even though I had many to try with. When a repair required moving the zebra strip, the display always had an element or two that were always-on or always-off afterward.

On the other hand, your description sounds more like a flexible PCB to me too... because zebra strips look like alternating colored and dark gray rubber. There's nothing metallic looking about them. And if it IS flexible PCB, then you can probably just use twisted pair cable (ribbon cable with every two adjacent conductors twisted around each other) to extend it. They use the flexible PCB in small electronics to make assembly easier, usually, so noise probably won't be a problem. Its not like lcd's are high frequency or anything, and the voltages used to get them to change state are pretty significant. The signal to noise ratio is very high...

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I don't think the problem was one of placement of the strip it is one of static damage to the LCD, been there, got the T shirt.

Yes, the strip is just a conduit, and its placement is fairly non-critical. It's the relative placement of what's touching both sides of it that's critical.