TI-59 Calculator Repair 

It's really a TI-59.

More than a TI-59 repair I would title this TI-59 Battery pack repair, that would be more accurate I believe 😉. Great video anyway, shows some interesting tips. Only cons, from what I've heard it's dangerous for the calculators components integrity to plug and power on the calculator with the wall adapter without a working battery pack, which you precisely show. 😢

These TI-59 calculators also have a built-in magnetic card reader for loading programs and data, with an electric motor to pull the card through using a rubber "gummy wheel". After 40 years, that will have perished. It is possible to repair it using a TI-59 gummy wheel repair kit, but it's quite expensive.

Thanks for the video. I have just started trying to bring my TI-58 back to life, but the battery metal connectors are way gone, due to oxidation. Back in the day, the manual or whatever said that if you used the charger without the battery pack attached, it would burn out its power supply. Mine actually went to a repair shop precisely for this reason, and they (very poorly) changed the 4 diodes you can see beside the battery connectors. The charger is actually just a transformer, from 110/220 to 3.3 VAC. I'm Brazilian, and this was my first programmable device, given to me by my parents in early 1980, as soon as I was accepted to the Civil Engineering course at UFMG. During the months before classes started, I taught myself some programming in it, and it helped me a lot during the next five years. Later on, I became a developer of engineering code, and eventually went on to get a master's and a PhD in Computer Science. The TI-58 was the beginning of all that -- even though it erased all programs and memory content when it was turned off!! (The TI-59 with a magnetic card reader was beyond my parents' budget, and theTI-58C, with constant memory, was launched a few months later.)

The calculator is a TI-59. The ML-25 refers to one of the programs in the master library chip you showed in the early part of the video. You get a bunch of those plastic cards, one for each library program. When you put it in the slot you can see how to use that program. You then enter in PGM 25 and that program is made ready to execute by reading it from the chip. That calculator has a card reader for magnetic cards, but that card (in the video) is just a piece of plastic to refer to since the actual library program is on the chip. Those card readers are hardly ever functional these days after so many years and probably also require repair. There is a problem colloquially called the sticky wheels problem that has something to do with the rubber rings inside the card drive, or so I'm told.

Thanks for the video. The batteries in ALL of the 1970’s SR & TI series calculators using these battery packs have the same issues. Plus they’re 50 years old!!! Your video should help many people interested in these old calculators, they CAN be resuscitated. Modern batteries should last for quite awhile. The power architecture seems not so well thought out. The batteries act as sort of a voltage regulator.

Nice repair and great idea to use HVAC tape. I wish I had thought of that. I’ve got the same calculator and used AAA batteries instead because it’s so tight. The battery AH capacity of today’s NiMH batteries is about 10 times that of those 70’s NiCads.

Both my TI SR50 destroyed due to leaking battery power packs. Looks like the same power pack used on the TI 59. Don't have this problem with the high quality old HPs which I also have.

Any idea what kind of connector I could use to charge the calculator? My power supply is long gone and I'd like to rebuild the battery pack but not sure how I'd charge it.

From what you say I think my ebay purchase of a power lead may've been hasty?