Casio FX-201P, 202P & PRO fx-1: the trilogy

[Geoff Quickfall]

Just a light note,

It started with a non functional Casio fx-201P. Easy fix, corroded battery contacts. So full disassembly, cleaning of PCB and case then reassembly.

Then along came the PRO fx-1 with the cards. Fortunately there is a card manufacturer out there (see link below). Here is the thread on the Pro

CASIO PRO FX-1

Next the Casio fx-202p arrived in non functioning condition. No display, but power was getting to the PCB. Trouble shooting the PCB especially the electrolytic caps and I could not find any obvious problems, other then one corroded battery contact which was not the issue.

So I was testing the PCB further, continuity checks, solder joints and visually when I got called away. I did not realize I had left the ON switch in the ON position. Since there was no display reminding me that the ON switch was ON, I put the calculator on the trouble shooting desk. My next step was to remove and test the caps and replace all of them.

Well I came back to the calculator and realized it had been on for the last 5 days. Batteries completely drained. Installed new batteries with the intent to bridge the caps with appropriate caps as a test until I hopefully found the offending cap.

Selected the calculator to ON and without any further ado, it functioned with a crisp bright display. Tested the various functions including the continuous memory. All functions are perfect!

So, I can only imagine that it may have been one of the electrolytic caps which reformed over the few days that the switch was in the ON position.

Can’t think of any thing else but now day 5 since the “repair” and still perfectly functional.

1) Casio fx-201P 127 lines of code in semi FORTRAN.

2) Casio fx-202P same as 201 but with continuous memory supplied by two 357 button cells.

3) Casio Pro fx-1 same functions as other two but with card reader.

[BobVA]

I think you're probably right - an electrolytic cap reformed. A very Zen repair! :-)

The PRO is way cool. Are those little hash marks next to the mag stripe on the cards just decorative? Or are they for clocking?

[Geoff Quickfall]

80 cut holes for clocking!

Doesn’t matter what speed you pull the card through, within reason. So unlike the 71b or 75!

Cheers, Geoff

[BobVA]

(04-15-2020 01:10 AM)Geoff Quickfall Wrote:  80 cut holes for clocking!

That is crazy! A “hard sectored” mag card :-) Thanks for the photos.

[Massimo Gnerucci]

(04-16-2020 08:12 AM)BobVA Wrote:  

(04-15-2020 01:10 AM)Geoff Quickfall Wrote:  80 cut holes for clocking!

That is crazy! A “hard sectored” mag card :-) Thanks for the photos.

Like on old floppy disks, with all those holes around the inner ring...

[jjohnson873]

It always seems that Geoff has a very pristine looking table to show off his treasures. By-the-way, the vacuum fluorescent displays are awesome! Thank you for sharing. But I'm curious if, somewhere in Geoff's home, are the multi-shelf racks that hold the hundreds, ney, thousands, of boxes containing the calculator and watches that he has accumulated, collected and repaired. You know there is a 12-step program for this affliction.

[Geoff Quickfall]

Prepare yours self,

Gunter and his son stopped by on the way to HHC a couple of years ago and it was a little neater then.

My wife rarely goes into this room although there are a lot of books. Now the books have all been read and the room is going to be gutted and redone. The shelving will be matching boxes all labelled with various projects, tools, and etc.

You will see two spectrum analyzer, two oscilloscopes, signal generator, capacitor tester, tube and transistor radios and of course a plethora of calculators.

[edryer]

Amazing Geoff

I'd never heard of the fx-202P

Assume was around '76 therefore just after the HP "C" models by a year or so.

[Guenter Schink]

(04-16-2020 10:13 PM)Geoff Quickfall Wrote:  Prepare yours self,

Gunter and his son stopped by on the way to HHC a couple of years ago and it was a little neater then.

Yes, that was most impressive. It's not only the vast collection of our beloved calculators but also the plethora of sophisticated equipment to get repaired almost everything that has some kind of electronic chips and/or wires.

And I had a draft of the almost completed The Book in my hands.

Günter

Geoff, what a great afternoon that was in September 2018!!!