TI 58 Repair 

Cool! I Still have a working Ti55 I bought with all the loot I made cutting lawns and taking care of neighbors pets during the summer when I was 15, in 1979. It was programmable sure but has very few program steps and is lacking in instructions compared to the more advanced programmable calculators. I wanted a HP41C but it was way above my pay grade. I would have settled for a Ti59 or a 58 or even a 57 but again, way more money than I could come up with. About 10 years ago, I nerded out on EBay and picked up a Ti59 with a broken power pin like the one you repaired with a PC100A printer cradle. I also picked up a Ti58C (constant memory) that I repaired the battery for. It works like a champ. I do love these old calculators.

I just got my TI-58 from an online seller. The PCB in my unit has a slightly different arrangement and some of the components are in different places than in yours (including capacitors and the "trimmed" chip in the corner). Clearly they have changed the design over years. My unit came with no battery pack at all and there was no indication on the PCB about the polarity of contacts. I learned from your video which is which - thanks!

It was released May 24, 1977, one day before the first Star wars movie came out...

Oh that's interesting, the board seem to have been the same as the TI-59, bit it's just not populated with the card reader circuitery. You notice there's a whole area without components on the right of the battery contacts. Also the whole space in the head of the case, under the display, is empty... Right where the card reader fits in a TI-59.

The TI-58 and TI-59 were introduced in 1977. The TI-58C was introduced in 1979 with some internal circuit improvements and that's when I bought my TI-58C. Also bought a printing cradle for it (PC-100A). The "wall wart" it came with is the AC9900/H-sw charger that can switch automatically between 120VAC and 240VAC input, and outputs 6.2V @ 200ma (hence the "sw" appended to its model number; models without the "sw" are 22VAC input only). Has a Euro two-pin plug and requires a simple and cheap two-blade adapter for North America (no need to change voltage). I'm betting it's AC in spite of its polarized plug for the calculator, which could make sense if it has a full-wave bridge rectifier circuit . . . which would chop that approximately in half and provide charging for the ~3VDC battery pack (NiCads are 1.2V). If you replace the batteries and get a wall wart made for it, use *only* NiCad as the charging circuit is *not* made for NiMH. I've got two battery packs, one original and a second bought to replace it when it went dead. I'm going to mod the original to take replaceable AA batteries - likely will still go with NiCads, and will mod the second when its cells eventually die. If you use anything other than NiCads, pull them out before plugging in a wall wart! Additional Notes: The US Army was using the TI-59 with the printing cradle on a limited basis to evaluate feasibility in parallel with the M18 FADAC, an ancient solid state field artillery fire direction computer that was fielded in 1960 (FADAC = Field Artillery Automatic Digital Computer). It's not a trivial problem as the trajectory is affected by meteorological conditions including temperature, humidity, air pressure, wind velocity (a vector that includes direction), and precipitation (type and magnitude). The TI-59 fire direction program was fully capable of handling tube (e.g. howitzer) and missile artillery with high precision, and it was faster than the M18 FADAC. the printer was required for record-keeping in the event of an investigation regarding an errant round landing off-target (very serious and extremely thorough). The TI-59 with printer was overtaken by the fielding of TACFIRE. One of the major concerns with the TI-59 was its robustness in a US Army field environment that would subject it to all manner of shock, vibration, dust, moisture, etc. It wasn't hardened for it. Had it been fielded, the contract for it would have requested special hardened models specifically made for those conditions.

Awesome video ! I’m way too young for having ever been near this stuff, but nowadays .. I do find the Casios to be way easier to use ..

When you use USB power, does the polarity matter on the external plug? Thanks!

The TI-58 & TI-59 were introduced to the public on May 24, 1977 Source: datamath.org/index.htm Cool video btw; I have recently acquired a TI-59 and an even older SR-52 from ebay, both of which need repairs, so your video will be a valuable guide. Thanks for posting. Greetings from Denmark.

Is it possible to use it from the currently available Lithium 3.7V batteries? I have one approx 1200mAh, brand new and I do not want any damage of the calculator when I plug the charger.

It is odd to see the chips piggy backed liked that in a professional instrument.