TI-83 Plus screen calculator fix

DSC_9788The other day I found my TI-83 Plus calculator which I used in college and I hadn’t powered up for years, so I put some batteries in and turned it on. Did I see black smoke? No…instead the screen was all garbled up with all kinds of junk, sometimes it would only have a horizontal line, or take a lot of button pressing to get it to even show anything on the screen. Turns out it was a¬†perfectly good calculator, brought back to life with a simple 10 minute soldering job.

Initially I thought, maybe that’s what $100 worth of calculator should last, a couple years, you’re not in college forever right? But before throwing it out I had to try to at least crack it open and see what’s inside and who knows maybe there’s a simple fix to bring it back to life, it was actually a really nice calculator.

The PCB and all SMD parts looked like brand new. Since it would clearly turn on and off using the designated keyboard buttons and was slightly responsive I though maybe the screen controller went bad but a closer look at the flex ribbon cable between the main board and the LCD screen caught my attention. So I did some continuity testing and it was a dead giveaway, most of the connections were in the megaohm range.DSC_9790

 

So I removed the ribbon cable Рwhich was a very thin plastic with just leftovers of what once were traces (you could almost see through). There was some residue left on the pads from the flex cable РI applied some flux and pre-tinned the pads with the soldering iron. Then I soldered some thin stranded wires to replace the flex ribbon cable.

Turn it back on and … it lives!!!
I’m greeted by a RAM cleared message – probably because the CR1620 battery was disconnected in this process. A little testing reveals it’s in perfectly good working order. Things like these make my day sometimes…