Calculator Texas Inst. TI-30 (old model) some keys not responding?

[Peter63]

Hello

My old Texas Instrument TI-30 calculator, not working. Some keys not responding?  Any tips for cleaning or ....

Peter

[shakalnokturn]

I do not know the model well enough to advise on the keyboard,  if they are soft rubber contact keys usually a little abrasion on a cotton textile is enough, you need to get any "shine" off the rubber, make them look even and dull.
Keyboards with metal domes are more annoying, you'll usually have a brown/black layer of oxidation where the dome circumference rests on the PCB, that needs cleaning off.
The most delicate still are keyboards with conductive deposit on mylar, they also suffer from brown oxidation.
Avoid solvents/contact cleaners on any keyboard that uses silver or carbon deposits on plastic.
Usually IPA is ok for carbon deposits on a PCB.

In any case start by looking for a cut track due to battery corrosion.

My tool of choice for cleaning contacts (Notice I have no tool of choice for cleaning my workbench...):

[Peter63]

Yeeehaa!!
After some cleaning tips from shakalnokturn, my Texas Instrument TI-30 from 1979 is now up and running   

[drussell]

Hmm...  I have one of those red-bubble-display TI-30s somewhere.  It was my first REAL calculator.  I wonder where it is, as I don't recall seeing it for many years, though it is probably around here someplace. 

I love how the digits kind of "roll up" on themselves when it calculates something, then you see it shift the answer back in.  A really nifty unit and a true classic.

I should see if I can figure out where I've stashed it. 

[rsjsouza]

One additional tip: if the operations on the calculator seem erratic, change (or charge) the battery - the calculator gets to a brownout state and can't properly discriminate between a single or multiple button presses, or sometimes it gets confused by which key was actually pressed.

Brownout circuity was not yet invented at that time...

[Peter63]

After 30 sec the calculator scrolls a decimal point on the screen (power saving mode). I recall that sometimes in the 80' when i used this
calculator most, it was irritating short power saving time (still it is). I measure some current consumtion used my power supply:
Power supply setting 7V, 0.100A  ( calculator 9V battery normally )
Current  Display status
0.006     Power saving mode (scrolled dots)
0.009     1 char
0.014     2 char
0.017     3 char
0.020     4 char
0.025     5 char
0.028     6 char
0.036     7 char
0.041     8 char

used 0.041 if display is filled with character 8, need to by some 9v battery