Casio CFX-200 Scientific Calculator Watch

Casio CFX-200 Still running, since 1983 and still worn daily.  The picture was taken June 3, 2006.  It's a great watch.

The liquid crystal display works as good as it did the first day I had it.  A few minor blemishes on the face plate and buttons, but completely functional with the exception of the light bulb which no longer works.  Actually, I disconnected the light bulb early on because I didn't like the idea of the extra battery drain every time I did a 'change sign' with the calculator.  Several years ago the buttons along the sides were beginning to stick, in the pushed in position.  I was able to determine that the cause was hardening of the o-rings used to make the watch water resistant.  After cutting away the hardened o-rings the buttons work perfectly again.  I'm just a little more careful around water now.

It's getting very difficult to find a battery now.  Everyone seems to be dropping the 2020 size.  My usual source, Digi-Key, doesn't even carry them anymore.  Actually, 2020 size batteries are still available, but with attached leads that are intended for soldering into pc boards.  I may try one of those and see how hard it is to remove the leads.  Some people report good success using a BR2016 (or CR2016) as an alternative.  It's the same diameter, but a little thinner.  (April 2007 update: I just bought a BR2020 online from Interstate Batteries.)

Feb 14, 2011 update.  About a year ago my watch started malfunctioning.  The date would spontaneously change to dates that were impossible.  Months with more than 50 days.  I would correct it and it would work okay for a few days, then it would do it again.  It's been steadily getting worse, now with random resets, so I've had to retire it.

Since being discontinued by Casio, I know of no other scientific calculator watch available to replace the breakdowns of the aging watches.  I became aware of the rising value of these unique calculator watches a couple years ago and put up this page just to satisfy my curiosity of how many people would find it with a Google search.  Check out the guestbook, lots of interesting comments.  Sorry, not looking to sell.

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The Manual

Table of Contents:
2 Reading the display
3-4 Stopwatch operation
5 Setting daily alarm time
6 Readjusting an error up to +- 30 seconds, Setting time, Setting calendar
7-11 Calculator operation
12-15 Calculation examples
16-17 How to replace the battery
18-19 Care of your watch
20-22 Specifications
23-25 Warranty certificate

Page links:
2-5
6-9
10-13
14-17
18-21
22-25