HP50G display tape - conducting paths

[mipa83]

Hi,

please help me with fixing my broken HP50G.
Batterie got leak and corroded the conducting paths between CPU and display.

I took of the tape for wathing:
* the connecting glue is now missing
* some conducting paths are broken

Do you have any idea how I could fix the conducting paths? Is there a solution for the glued connection?

Thank's a lot
Michael

[cruff]

Maybe you could use conductive epoxy to repair the traces, obviously you'd have to mask off each broken trace individually. You might not be able to solder a wire to effect the repair, unless you had a low temperature solder. Those types of display connections are terrible for repair.

[mipa83]

Hi cruff,
thank you for your advice.
Do you have any idea how i could repair the end of the cable? The conducting paths where glued somehow to the display. After I took them off, the adhesive/glue property was gone. Do you know how to repair the glue/adhesive?
thanks a lot
Michael

[ijabbott]

(02-26-2020 06:41 AM)mipa83 Wrote:  Hi cruff,
thank you for your advice.
Do you have any idea how i could repair the end of the cable? The conducting paths where glued somehow to the display. After I took them off, the adhesive/glue property was gone. Do you know how to repair the glue/adhesive?
thanks a lot
Michael

It's a heat-seal film connector (although the exact wording varies). The glue is hot melt glue and the traces are some some sort of carbon-based thermosetting resin.

You could try and iron it back on, but I wouldn't rate your chances of a successful outcome.

[Nigel (UK)]

For heat seal repairs you might find this helpful.

Nigel (UK)

[mfleming]

If the original flex has a standard conductor pitch (distance between traces & trace width) then it is possible to buy a ready-made jumper replacement. Look for one from a suppler like Mouser - search on ffc/fpc jumper cable. You'll likely have to settle on one with more traces and slightly longer than the original. Sealing the cable to the board would be a very different problem though. One would normally use a surface mount connector, but hand soldering one to the board yourself would be tricky.

[cruff]

(02-26-2020 09:43 AM)Nigel (UK) Wrote:  For heat seal repairs you might find this helpful.

That procedure looks similar to how Dave Jones of the EEVBlog has tried to repair LCD displays on various items, some as large as big screen TVs. The success rate is probably very low. If you can find a suitable replacement cable, that might be the best chance of managing to effect a working repair.

[mipa83]

thank you for your advices - I haven't tried yet to fix the display.
I extend the calculator with bluetooth:

https://www.instructables.com/id/Bluetoo...ken-HP50G/