Texas TI-34 solar scientific calculator from 1987

[jebem]

Recently I have acquired a bunch of old used machines in a local flea market.

This model is a nice calculator powered by a single power source based on a four elements solar panel.
This one was made in 1987, November.

This machine was heavily used and abused, showing dents and marks all over the place, and heavy paint worn on the metallic front panel.
It was even opened and the PCB removed by destroying the plastic rivets and later fixed back with cyanolit glue that have also stuck the keyboard membrane to the PCB because the glue leaked thru the PCB holes.

But it still works fine after all these years and misuse.
I have dismantled it and reassembled it with success as well.
However I didn't fix the plastic rivets for now, because the back cover have several points of contact with the PCB, forcing it to be in place against the keyboard.




Forensics result (9 sin cos tan atan acos asin): 8.999998637




Switching to Mode Hex: NOT(FFFF) = FFFFFF0000
Switching back to Mode Dec = -65536




Back cover label:
Texas Instruments
I-1187
Assembled in Taiwan
R.O.C

[jebem]

The PCB is fixed by plastic rivets in the keyboard area, and screws in the processor/display/solar panel area.



Unfortunately it is not possible to remove the keyboard membrane because someone made a mistake when using strong glue to do a repair.




SoC processor: Toshiba T7988 8740H Japan
PCB ref. 10TI34-21B

EDIT: Amazingly, the T7988 processor datasheet can still be found!



Power supply limiter/regulator: a 1.75V LED and a 22uF capacitor in parallel with the 2.2V solar panel.




LCD display. Zebra strip used to connect it to the PCB.

[jebem]

Four elements 2.2V solar panel from National. Two zebra strips used to connect it to the PCB.



General parts view.



Power supply details.
The solar panel generates 2.2V unloaded (off-circuit) under strong light conditions, and 1.75V under load (in-circuit), due to the tiny axial 1.75V LED installed in parallel acting as a limiter/regulator.
The 22uF capacitor gives about 10 to 20 seconds memory contents retention under zero light conditions.



The tiny axial 1.75V LED can be seen here being tested off-circuit.
Check the bright red light at 3 seconds mark.

[DavidM]

Nice write-up, Jose!

I've got one of those as well, apparently one month younger than yours (I-1287). I recall finding it on sale somewhere (no longer remember where), and thought it would be handy to have at work. I ended up getting more use out of it than I thought I would, mostly for occasional base conversions while coding.

You didn't mention a slip cover, and the condition of your unit makes me think you might not have received one with it. Mine came with one, as well as a quick reference card that fits in that same cover. Let me know if you'd like a scan of it.

[jebem]

(05-04-2016 06:26 PM)DavidM Wrote:  Nice write-up, Jose!

I've got one of those as well, apparently one month younger than yours (I-1287). I recall finding it on sale somewhere (no longer remember where), and thought it would be handy to have at work. I ended up getting more use out of it than I thought I would, mostly for occasional base conversions while coding.

You didn't mention a slip cover, and the condition of your unit makes me think you might not have received one with it. Mine came with one, as well as a quick reference card that fits in that same cover. Let me know if you'd like a scan of it.

Hi, David, Thanks for your kind words and additional information.

Yes, the slip cover is missing. My machine is really in bad shape, I probably will look for another one in the future.

I searched for the quick reference card in the net and failed to find it.
So I would appreciate your offer when you have the time to scan it.
We usually kindly ask Kate to upload these legacy documents to her website. I can do it or you may directly contact Kate.

[DavidM]

(05-04-2016 06:56 PM)jebem Wrote:  Hi, David, Thanks for your kind words and additional information.

Yes, the slip cover is missing. My machine is really in bad shape, I probably will look for another one in the future.

I searched for the quick reference card in the net and failed to find it.
So I would appreciate your offer when you have the time to scan it.
We usually kindly ask Kate to upload these legacy documents to her website. I can do it or you may directly contact Kate.

Here's a google drive link for the scans: TI-34 QRC. The card has info on both sides, so there's two pages.

I've also included grayscale conversions of both pages (with enhanced contrast), as the original background is very dark which tends to make the cards less readable IMHO.

Enjoy!
- David

[jebem]

(05-04-2016 08:39 PM)DavidM Wrote:  Here's a google drive link for the scans: TI-34 QRC. The card has info on both sides, so there's two pages.

Enjoy!
- David

Thank you so much, David!

[kordewiner]

I found this thread via Google, thank You Jose Mesquita. I still own the TI-34, the quick chart and the German manual booklet with 51 pages. Photos: https://photos.app.goo.gl/rGzswiDQPngYvVAh8

       

[ijabbott]

Various cheapo scientific calculators such as the Texet Albert2 seem to be 100% TI-34 compatible function-wise (I'm not sure if numerical results are identical), but with different key layout and legends, and slightly faster than the original.

[Eddie W. Shore]

Jose,

I love your posts on vintage calculators.

Eddie