I've probably had the tab with the following link open in my browser for six months or more, reminding me to try out this technique for fixing fine-pitched LCD ribbon cables. However, I brought it up on IRC last night, and CVSoft indicated that he has tried this exact tutorial, and found it to fail after a few weeks. Sad news for prospective repair of those fine-pitched cable issues like missing rows and columns.

http://www.instructables.com/id/How-to-remove-and-re-attach-LCD-Ribbon-from-a-PCB-/

The TI-81 featured a couple of posfs back failed again, with two ribbon cable connections going bad. I did yet another partial repair, and it works again!

I've repaired a few ti 83 screens myself but in a quite different way. I don't use wire at all. I just use the legs of resistors and leds. Here's how to do it this way:

Prelim.) Completely remove ribbon cable, use flathead screwdriver to scrape off residual adhesive, pre-tin all contacts, and obtain lots of led/resistor legs. (I have a bunch from my 3D printer led soldering adventures.)

1.) Cut 1cm off of the leg DON'T BEND IT YET
2.) Solder one end of the leg to the screen contact with the rest of the leg sticking off over the motherboard (you may need a pair of needlenose pliers so you don't burn yourself)
3.) Using a flathead screwdriver push the leg down towards the mother board so it bends in to a └┐ shape and touches the respective contact
4.) Solder the other end of the leg to the contact but do it FAST because the other end will melt off if you stay on the leg for more than a second.
5.) Repeat for all contacts

That's it. Here's what it looks like when it's done:

Interesting, thanks for sharing that technique! As long as you keep the LCD and mainboard within the case while you do it, it seems like it would be a little bit easier, especially depending on people's soldering experience. I wish we had a reliable way to repair the conductive glue on the fine-grained ribbon cable so we could once and for all have a definitive guide to graphing calculator repair. CVSoft, didn't you say you had something semi-reliable?

Only for TI-82s and dark blue TI-81s.
Apply more pressure to the LCD board by putting more foam / soft, even stuff on the foam block on the rear housing. The foam tends to flatten over time, causing the LCD to sag in the housing and lose pressure against the fine ribbon cable. I would only recommend it if there are many rows/columns permanently missing.

This works but I have one issue with it. There is no stress relief. A calculator in say a school bag,repaired that way, will probably fail sooner then later due to the pads lifting. There is quite a bit of play on the LCD that your now are putting on the copper pads. the ribbon cable was there to keep that off the joints. Just some food for thought. Still a beautiful job though!

After yet another failure, I finally replaced the entire ribbon cable on that TI-81. I used 32-gauge enameled magnet wire because it's easy to work with (you don't strip it, the enamel melts away).

There's been no action in this thread in some time. I was wondering if any new improvements have been tried and proven on replacing/substituting the fine black LED display ribbon cable? I've been repairing TI-83's/84's/86's for some time now, and lurked this thread over the years. My niece brought me her older hand-me-down TI-86 which she's been using for Jr High school work because it has 4 horizontal lines of missing pixels and slowly increasing the number. I know they're only like $25 for a used one on Eb but I've been looking for a solution for this for years on other models as well. I've tried the usual tricks I do with compressing the foam/cable connection, hair-drying, etc. and got two to go away intermittently, but they come back fairly quickly. The top-most one, I can get to go away by pressing the glass and board together, but it comes back within a week or two. The bottom-most one I can play with the cable midway, and get it to work, but not long enough to even close the case.
Has anyone tried say sacrificing an already broken one to try methods of removing the LCD to access the cable connectors beneath it? It appears both ends are inaccessible beneath the foam and boards. Maybe heat or some solvent like goo-gone or alcohol, or stronger?
Any known methods to shorten or "jump" the thin cable either midway or connect just one or two full strands? The way it is wrapped around and folded multiple times seems like just ASKING for quick deterioration.

Don't let this thread perish, it's been quite useful. Love the photos too.

BTW, along the lines of using the old hard drive cable for the coarse cable, has anyone considered substituting an easily obtainable flat ribbon cable, say from an obsolete printer. Those are quite durable and one of those cut into pieces could probably substitute for 3 or 4 TI cables, burn or dissolve off the plastic on the ends, and tinned) or from an old 10Mb hard drive. Don't know how well they'd take a very sharp bend though. Or maybe find a source for one for use with another brand of device. Has anyone considered contacting the manufacturing company (in China likely) to get OEM replacements. I'm sure they'd be willing to sell them to you super cheap if you buy a bunch. You could then split the order or sell them online. Would they be interchangeable enough to use one type on multiple calculators? I don't do enough of them to take the time right now or I would look into it more.

Keep up the great work!

The coarse cable isn't very critical, so it's probably just a matter of what you have handy. If you were planning to replace a lot you could buy a large quantity of bare ribbon cable matching the pitch and width, but I don't think anybody's dedicated enough to do so.

Probably not; they're not really designed to be serviced. It's basically COG assembly, which is engineered for cost and size rather than serviceability.

In general, I'm convinced a more useful approach to mass repairs of fine ribbon failures would be designing a replacement LCD assembly (driver and display) that can be dropped in rather than trying to repair those microscopic fragile cables.

You intrigue me, sir. I suspect the hardest part would be finding a matching LCD; I expect a 128x64 pixel panel might be the easiest way to go.

Has it been identified which conductor trace will cause the solid black screen?

What do I do? Do I simply check resistance across all conductors and splice a jumper into any one showing high resistance?

You guys who are doing this (have done this) Have you tried to just remelt the solder joint or have you identified a break in the ribbon?

It sounds like the joints aren't soldered but rather glued making it a more difficult repair than just remelting.

I've worked with LCD's that the conductors are a neat piece of carbon impregnated rubber formed in segments. The above conductor material is then pressed between the LCD contacts and the PCB contacts.

The LCD screen on the Chevrolet Corvettes has troubles including the sun damage to the polarized film. There is quite a bit of information about repairing them. Yet not for the average sausage fingered grease monkey...

When i finally get my micro torx drivers and get into it, perhaps I'll figure out something.

I just got in two TI-83 Plus calculators from eBay with screen issues. They had blue and purple polycarbonate cases. These seemed somewhat rare so I figured, worst case, I'd transfer another calculator into the colored shells. But I'm handy with a soldering iron so figured I would try my hand at repairing or replacing the ribbon cables.

I was looking into repairing a friend's GameBoy and saw this video: https://www.youtube.com/watch?v=-Cj5Pzuz06M . Long story short, he uses a soldering iron to attempt to re-bond the ribbons.

After disassembling my TI-83s and cleaning all of the display contacts with 91% isopropanol (can't discredit someone spilling something on the calculator), I took my Weller WES51 soldering iron with a PES51 pencil and a wide tip, set it to 375 F, and applied gentle pressure to the back side of the ribbon and PCB. I spent about 4 seconds on each individual pin, then, worked back and forth across the whole ribbon.

While I was doing that, the calculator shells, buttons, and silicone domes took a bath in my cheap Chinese ultrasonic cleaner, in reverse-osmosis water with a denture tab or two. I rinse with tap water and do a final rinse with distilled water to prevent spotting, then dry thoroughly with microfiber towels and a fan. I gave the screen a wipe with isopropanol and a finishing wipe with the micro fiber cloth.

After this, both calculators looked and worked like new. Success! I'll try my hand at others in the future - maybe a TI-68? (Not a typo, 68, not 86.)

Excellent work - have you thought about documenting your process on video?

I'm pretty surprised that worked. From what I understand, the Game Boy's ribbon cable is soldered to the LCD, and the calc screens are basically taped on. Did both the 83+s have problems with lines across the screen? in my experience, that's relatively rare, though I don't have much experience with the later 83+ revisions.

Maybe if the joints are glued, they are thermoplastic enough to rebond with some heat. Let us know how it holds up. Thanks for posting.

I've done some reading, and it seems like the ribbon cable is the main culprit of the screen malfunction. I am going to do a fix for a friend and I was wondering what gauge wire to use? I've checked the continuity and it seems that the whole ribbon cable needs replacing. Any insight is appricated!

Is this ribbon connector also at fault for when there are a few "squiggly" clumps of pixels on the screen that are always black even when the calculator is off? I loaned it to my daughter and when she brought it back she said it just started doing that...I'm hoping she didn't drop it or something sharp poked the screen. The glass looks fine, its just got a clump of tiny lines that look like molecules or tiny trees in the winter (heh) in one spot always visible. I pulled all batteries (even the backup) and let it sit for a few days and the clump of pixels are still showing on the display without batteries. Any ideas on fixing this, or even troubleshooting?

I'd assume that this is a damaged LCD issue, and I don't think it can be fixed. I'm no expert, but this has happened to a lot of the LCDs of calculators that I've seen and there's not really anything you can do about it. I think most likely one of the pixels burst but that could be completely stupid on my part so don't listen to what I've said if it's all completely wrong