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Full Version: Canon Palmtronic F-6 scientific calculator from 1975 (kind of rare now?)
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Found this one during my last trip to Porto city last week, when looking for vintage books in a old bookstore.

This machine uses a green Vacuum Fluorescent Display with 12 x 7-segment digits.
However, two digits are reserved for minus signals and "memory in use" and "Error" annunciations.
Another two digits are used for exponent.
This leaves 8 digits for mantissa.

After power on, the calculator shows a "0.^00".
2^5 (a^x) produces a good enough result of: 31.999974^00

[Image: Canon_Palmtronic_F-6_001.jpg] [Image: Canon_Palmtronic_F-6_002.jpg]

The usual forensic check gives this result: 12.199423^00
(Degrees mode. 9 sin cos tan tan^1 cos^1 sin^1)

[Image: Canon_Palmtronic_F-6_003.jpg]

Trying 1000 ln followed by e^x result in: 999.99964^00

And the classic 1 / 3 followed by * 3 gives a result of: 0.9999999^00
A honest result from this 1975 calculator.

[Image: Canon_Palmtronic_F-6_004.jpg] [Image: Canon_Palmtronic_F-6_005.jpg]

Pi internal constant stored value of: 3.1415926^00
Clearing the calculator and doing e^x twice results in: 2.7182804^00

[Image: Canon_Palmtronic_F-6_006.jpg] [Image: Canon_Palmtronic_F-6_007.jpg]

Not as good as a HP-35 machine, but it is not that bad either.
The case is very robust and well built and the keys have a good travel when pressed despite having no mechanical clicking, but at least they never fail to register.

[Image: Canon_Palmtronic_F-6_008.jpg] [Image: Canon_Palmtronic_F-6_009.jpg] [Image: Canon_Palmtronic_F-6_010.jpg]
A single screw holds the back cover that also have plastic notches to maintain structural rigidity.

[Image: Canon_Palmtronic_F-6_011.jpg]

Does anyone understand what is written in this white label on the back cover?
I suppose it is Japanese, and I saw another calculator picture in the Internet with the same label.
Although my calculator is missing the English label that I can see in that other Internet picture.

EDIT - Used ABBY Fine Reader and some Japanese text was recognized and later googled:

CANON 保証書 = CANON Warranty card
197 年 月 日 = 197 year month day

内容は使用I兑明赛に驴鲛れてい = I use content wa ni donkey race against the next shark made me cry te い ???

Obviously the label printing is worn to the point that it is impossible now to be machine readable.

[Image: Canon_Palmtronic_F-6_012.jpg]

Injection molded keys.

[Image: Canon_Palmtronic_F-6_013.jpg] [Image: Canon_Palmtronic_F-6_014.jpg] [Image: Canon_Palmtronic_F-6_015.jpg]

Shielding spring connector detail.
It connects the metal front plate to the machine PCB ground.

[Image: Canon_Palmtronic_F-6_015A.jpg]

The Hitachi HD3699 SoC processor is complemented by a DC-DC power supply converter to generate the required high voltage to illuminate the VFD.
The PCA set includes:
- The Processor/Power Supply/VFD main PCB, which in turn holds the Power Supply PCB;
- The Keyboard PCB;
All the three PCB's are soldered to each other by using single core wiring.

I measured the current consumption using a 4.5V power supply.
After power: 60mA
All digits on: 82mA
Calculating sin: 65mA.

This translates to a power consumption of a minimum of 270mW and a maximum of 370mW, much less than the declared 0.6W value in the English back cover label (the one missing in my machine).

[Image: Canon_Palmtronic_F-6_016.jpg]

The VFD terminals are clearly identified.
Terminals "1" to "12" for the digits selection, then "a" to "g" and "dp" for the 7-segments plus decimal point selectors.

The electrolytic capacitors have a working voltage of 50V. I didn't care to check them as the machine works flawlessly with a bright steady VFD light emission..
From the two power supply transistors, only one have a identification label, with "D467" (2SD467 NPN Si).
The TDK transformer has a code of CD-1015, Japan.

The date codes in the transistor and in the SoC processor is "5L".

Visible in the picture is one broken black plastic pin that I couldn't find its original place.
This machine was opened before by others, but apparently nothing was modified or repaired as all components solder joints looks tom be untouched.

[Image: Canon_Palmtronic_F-6_017.jpg]

The 12 digit VFD is soldered to the Processor PCB.

[Image: Canon_Palmtronic_F-6_018.jpg] [Image: Canon_Palmtronic_F-6_0209.jpg]
Thanks Jose

Another interesting read

Cheers, Terje
How very curious. I once had a Teal SR82 that gave that same 12.199423 forensic test result. Must have been the same chip.
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