TI-59 card reader note

[Hiwi]

Hi John,
yes i have a nice working TI-59.

I like the Ti-59 very much but my focus is more on HP caclulators.

Some friends of mine collect all kinds of TI-59/58 stuff and I have to repair all these calcs and PC-100 printers, ouch.

Actually they are very cheap in comparison to HP calcs.

So meanwhile i have a huge 'collection' of spareparts.

Common problems are corrosion, problems with the cardreader, keyboard and memory and bad soldering. The PC100 has often problems with the powersupply, bad soldering shorted zeners...

The TI cardreader is a very robust construction, that could last forever. I had working calcs with capstans looking like new and others totally squished. I don't know why.

Cleaning the capstan with alcohol destroys the original rubber in any case! Bad experience.

Regarding the caps there are two kinds of tantalums on the board, the standard "teardrop-shaped" and the silver cylindric ones. These are very high quality and my experience is that they also last forever. The series resistance is always perfect. I never had a fail.
They are very expensive and hard to get. I bought a small stock from a german distributor in standard values.

Completely different than the cylindric type are the teardrop-shaped caps.
They often show a good cap value but a high serial resistance.
I replace them. But there are quality issues on the market. I prefer high quality Vishay or Kemet.
Sometimes i use smd versions.

I have done lubrication of the gears as a standard service with - guess what - moly-di!

I have a little tube of moly-di which is an oil additive for the gearbox of my Moto Guzzi motorcycle. I had nothing else on hand :-)

Ralf