Texas Instruments TI-1750 (3rd design)

Date of introduction:  1978 Display technology:  LCD (yellow)
New price:   Display size:  8
Size:  4.5" x 2.7" x 0.35"
 115 x 68 x 9 mm3
Weight:  2.3 ounces, 65 grams Serial No:  167773
Batteries:  2*LR44 Date of manufacture:  mth 02 year 1978
AC-Adapter:   Origin of manufacture:  Japan
Precision:  8 Integrated circuits:  Toshiba T3709
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner
    Download manual:   (US: 0.8M Bytes)

This TI-1750 looks identical to the 2nd version but uses an even cheaper internal construction. The connection between the LC-display to the printed circuit board (PCB) was changed from the former discrete coil springs to a zebra-stripe (an arrangement of conductive and isolation rubber pieces). 

Before the TI-1750 was later replaced with the similar TI-1750-II it got a massive cost reduction. Don't miss the 4th design of the TI-1750.

Read more about the history of the TI-1750 here.
It is obvious that the 1st design used three batteries instead only two of this 3rd design. TI-1750_Back.jpg (78146 Byte)
The internal construction is totally different. The 1st design uses a huge 42-pin DIL (Dual In Line) plastic housing instead this 43-pin QFP (Quad Flat Pack) housing. TI-1750_V3_PCB.jpg (74296 Byte)
The 3rd design of the TI-1750 uses a battery holder to accommodate 3 coin batteries. One of them is blocked with a dummy battery. TI-1750_V2_BAT.jpg (43109 Byte)
Later models cut the battery holder down to 2 places. TI-1750_V3_BAT.jpg (43326 Byte)

There are different rumors which companies designed and manufactured the TI-1750, usually you get Toshiba and Sharp. Comparing the 4 versions with similar calculators manufactured by Sharp we could reject this speculation. On the other hand we canít believe that Toshiba used a calculator chip from competitor Sharp.

Searching all parts for a hint to possible manufacturers gives you the Sansyu logo.

Sansyu Precision Co., Ltd. (Hieda, Japan) was founded in 1976 and specialized in precision plastic and metal processing. Main products are Injection Molding, Metal Stamping and Assembly. The construction of the TI-1750 makes heavily use of both injection molded plastic parts (display frame, internal frame, on-switch, keys) and sheet metal (housing top and bottom). Fits perfectly ! Let us assume that Toshiba designed the calculator and Sansyu Precision was responsible for both the tooling and manufacturing. It could be possible that the 1st design was changed to both Toshiba and Sharp calculator chips to get a second source in the case of component shortage.

Press the X-RAY button and view the internals of a TI-1750. 
 Watch carefully and you'll notice the odd battery compartment !
 (Pictures provided by Edward Soudentas)

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© Joerg Woerner, May 16, 2002. No reprints without written permission.