Canon Palmtronic F-6 scientific calculator from 1975 (kind of rare now?)

[jebem]

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




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




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.




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



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.

[jebem]

A single screw holds the back cover that also have plastic notches to maintain structural rigidity.



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.



Injection molded keys.




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



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).



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.




The 12 digit VFD is soldered to the Processor PCB.

[Terje Vallestad]

Thanks Jose

Another interesting read

Cheers, Terje

[Bob Patton]

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