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 download 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

[Mjim]

Thanks jebem for this teardown, I just got a hold of the 2nd edition of this TI-34 (blue buttons instead of red); it's in better condition, but far from perfect.



One thing that got my attention was the fact that the front cover on yours was metallic. The 2nd version I have is just a plastic front cover and even some of the ones I've seen online with the red buttons appear to be plastic as well (maybe they are just much better condition?).

Also my one has a 10uF Electrolytic @ 6.3v instead of the 22uF, which is a little odd as I've seen the links at datamath and they seem to still be 22uF in later versions.
http://www.datamath.org/Sci/Modern/TI-34_5.htm

Really love the contrast on this display, and it's low-light performance is really good. Persistent engineering mode is nice plus on a pure solar-powered calculator.

[Dave Britten]

This is a pretty nice model that was popular in schools back when I was in around 7th grade. It falls somewhere in between the TI-30 Solar and TI-36X Solar in terms of functions. I recently got one via ebay, along with the included TI-34 Computer Math Book. It's a nice collection of math explorations and problems intended for use with the 34.

[Benjer]

(08-03-2021 04:34 AM)Mjim Wrote:  One thing that got my attention was the fact that the front cover on yours was metallic. The 2nd version I have is just a plastic front cover and even some of the ones I've seen online with the red buttons appear to be plastic as well (maybe they are just much better condition?).

I know of one other TI model that switched from metal faceplate to plastic during its production run, and that's the TI-68. The earlier models were painted metal like Jebem's and the later models were all plastic.

Similar date of production and similar (but not identical) button appearance too.

[Mjim]

It seems newer revisions were about cost-cutting, with a reduction in the size in solar panel (which is a shame since it's low-light performance is pretty good). Version 1 & 2 (Op's and the one I posted), were both made from the same company in Taiwan, but then production bounced around a few different companies with the later versions.

Still the loss of the metal front and a reduction in the size of the electrolytic from 22uF to 10uF (would the savings even matter?!), even version 2 was cutting costs.

I spotted a few version 1's on ebay and they had the metallic front panels, so I must of been confusing version 1 with version 4 when I first looked.

@Dave Britten
Nice that it comes with a TI-34 math book! I'm waiting on a Sharp EL-506A to arrive which also comes with it's own version of a math book on top of the manual. I love the big manuals that older PC games came with and the same holds true for calculators

[Xorand]

The TI-34 was my go-to device when starting my computer programming career in the mid-1980s. I started out with the older LED display TI Programmer towards the end of college, but switched as soon as I saw the solar-powered TI-34. I kept it for a while but sold it a few years later.

[80sTI34]

I have a TI-34 that only works if the region between the solar panel and the display is lightly pressed down. Any suggestions on what the issue could be and how to fix it?

[LEDfan]

@80sTI34
From the teardown this area is exactly where the zebra strip makes contact between the solar panel and the PCB. Zebra strips rely on a tight fit between component and PCB. If the tolerances aren’t quite right in your calculator, then pushing in this area might be making a connection, and powering the calculator.

If the calculator stays on for a few seconds after you have pressed down, sufficiently long enough for the capacitor to charge, then it is likely this that is causing the issue.

If you’re able to enter digits, and they reappear when you press down, then it might be a similar issue but with the connection to the liquid crystal display, as this would suggest that power is getting to the board.

Also in this area, there is the chip. This might have a poor connection to the board, perhaps a dry solder joint or mechanical damage from dropping.

[Eddie W. Shore]

I have a TI-34 and clone of that TI-34: Victor 930-2

[AMiguelTrindade]

That was my first scientific calculator and it still works! :-)