I just picked one of these up at an estate sale I stopped into. I believe this unit was made in 1968 or 9. Upon getting it home, as with old radios and TV's, I did my usual take the covers off for a look see before dim bulb power on. Unfortunately, it has a seriously wasted electrolytic can cap. This can is covered by clear plastic. The electrolyte pushed it's way up completely around the can under the plastic, making the values unreadable. Good thing is, none of the stuff got on the circuit board as far as I can see from the top. Would anybody happen to have a service manual, or a lead to the service information for this unit? I don't see anything right off the bat online or at the antique calculator sites. I guess my next stop is one of the calculator forums. Thanks

Here's a site with some info and pics, they own a couple Friden calculators. Might be source of further info if you wrote to them.

http://www.oldcalculatormuseum.com/friden1162.html

If you know the approximate voltage of the circuit you should be able to make a fairly accurate guess as to the value just by the size of the cap. Can you take a picture of it?

The cap is 3" high x 1" across. Voltages that I can see on other caps range from 40V to 300V.
I can't get at the bottom of the board the cap is mounted to until I remove a large delay line assembly.

I would suggest removing the cap and cutting the plastic off, then carefully wash it. The value may still be readable.

If you can't read it, you can try connecting an electrolytic of about 350 volts at 20uf and measure the voltage. If it is around 40 volts I would expect a capacitor of that size to be around 1000uf; if it is closer to 300 volts I would guess around 20-30uf.

Thankyou for the info. I think I will restuff or replace all those before I try to power it on, with the looks of that cap, I don't trust any of 'em.

Well I got the cap out, removed the plastic and cleaned up the area of the nomenclature with a Dremmel wire wheel. I can see that the cap is rated at 200uf, unfortunately, the breach in the can is precisely where the voltage rating is. So, I'll do as suggested, see what I have in likely caps to tack on there temporarily, and bring it up to where I nan measure what the voltage is. If I don't have the caps to do this experiment, I guess I'm off to one of the calculator forums to see if they have a spec for this cap

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Are you sure that is 200uf; looks like 2000uf to me. If it is the voltage rating is probably 50 or less.

delete.

That thing is really neat, never saw a calculator with a CRT before!

I've seen a few late 60's desk calculators. Even a few with CRTs. From the looks of it, it appears to be an electrostatically deflected tube. I would have expected to see deflection yokes (magnetically deflected) ! ... real cool !

+1

It could be 2000 mfd, I was kind of undecided looking at it, with all the corrosion, but now that I look at it, that could be another zero there.

Johnnysan, ya nailed it! A member of the oldcalculatorforum Google group came through, 2000mfd @ 35v. I went off to Abel Electronics to pick up a replacement. 2200mfd @ 50v radial. Once the new cap is in, then comes powering it up with the dim bulb and variac, and if it seems to basically work and has promise, I'll go the rest of the way and invest in replacing all the e-caps. Thank you again for your guidance.

I temporarily tacked the new capacitor in...



Hooked it up to my dim bulb, and brought the voltage up over an hour or so...



And, at about 90v, the display popped on, it works!



Reverse Polish Notation, RPN, 22/7: press 22... press first number key... press 7... press divide... = pi.



Now to purchase the rest of the caps, install them, and fix various minor issues like sticking keys and small plastics cracks. And it will be ready for end of the month checkbook duty!

http://www.oldcalculatormuseum.com/friden1162.html

Nice to see it working !

I did a little reading on that machine. Its display is a 3WP1 tube. Electrostatic deflection. I have one of those in my tube stash. Only $1195 in 1971 !

That thing is off the hook!

Awesome calculator. I wouldn't mind having something like that.