Kudos to TI...

[blackjetrock]

(11-27-2023 01:32 PM)Jeff_Birt Wrote:  I suspect that if an LCD is run for an extended period of time with missing segments it may be permanently damaged. I had new zebra strips made for the TRS-80 Model 100 LCDs and while this fixes many problems I have still run into the issue of a missing row. Since these LCDs are symmetrical you can rotate them 180 and the same row, now flipped top to bottom is still missing. This may also be from some damage to the conductive coating on the glass. I don't have the equipment to try and get a good view of the conductive pads on the glass.

I don't think a disconnected LCD row would suffer from anything, if you apply DC it's not happy, but applying nothing? More likely LCD coating, as you say.

Quote:I have had good success resealing FFCs that have not moved. A few I have had to try a few tries at it. As you say alignment is a bear. I have noticed that several sellers on Aliexpress are now selling ends of rolls of the Anisotropic Conductive tape. Perhaps only a meter or so per roll and supposedly they are not yet pat their expiration date. I will order some to try when I get a good repair candidate I don't mind sacrificing to the gods of learning and knowledge.

If you mean 3M 9703, then yes, you can get bits of it. I have tried it and it does work, but the cells are too big for the PC-G850 connector pitch, so it didn't work for me.

Quote:In the TRS-80 PC-2 service manual they show an interesting technique for reattaching the FFC on the cassette/printer interface. (Providing you can detach it without damage.) They show offsetting it ~1mm from the edge of the pad. This gives an exposed bit of copper to touch your iron to solder the FFC to the PCB.

Can you solder to heat seal cables? The ones I have seen are carbon traces, as opposed to the FFC which is a copper trace.