I have some cheap device with a small color TFT display conncted to the board with some tapelike conductor -- which has broken 1 or maybe even 2 conducting lines (I can actually see the tiny gap with a lense I use).

(By the way: they've got broken because a control button is strangely close to the conductor -- so it was pressing it and slowly damaging it over time... figure that design error...)

Now the question -- how to repair it?
(if there is not some known (adequate) procedure, consider it a philosophical question -- just for the cause of wisdom) :)

Come on people...

What's that material tape is made of? Maybe I can find some solvent to expose conducting lines...

The tape is usually made of MYLAR.
Can you disolve it - NO

And depends on how steady your hands are, and skilled with a low wattage soldering iron and exacto knife can you fix it.

If you could strip back 1/16" of the mylar and had a conductive ink pen, that may fix it. (then re-cover with SCOTCH brand tape)

But those are only possible solutions. The easiest way is to find a broken unit- same model on eBay, and replace the wire.

Questions:
Did you do a continuity check from the test points on the board to the other end of the connector?

Is the other end of the connector directly connected to the TFT?


Also that site doesn't allow external image linking

(thanks for reply)

So THAT orange transparent stuff from the picture is mylar! ...

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The TFT LCD is soldered to the board (20 pins or something), and I can't figure how to reach the other end of the tape conductor (on the LCD) without damaging it. So I can't even test the lines end-to-end.

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I will try to scratch that stuff from the conducting line, although it's to glossy, to traction at all...

...What about melting it?

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I don't have a conducting ink marker.

I soldered a tiny wire to a component on the tape (resistor or something) which originaly led to the severed line, but when I tried to solder the other end of that tiny wire to the severed line leading to LCD the drop couldn't stick to it... How to tackle this problem?

Use the conductive ink pen. You may cause irrepairable damage doing it your way.

I gave the solution and I cannot tell you how to do it wrong. I only know the right way.