Friden EC-130 Help

jwsmobile jws at
Mon Feb 2 01:44:16 CST 2015

On 2/1/2015 9:03 PM, drlegendre . wrote:
> Hi Kyle,
> While I certainly cannot claim any level of expertise in the matter, I do
> happen to have a functional EC-130 here. Or I should say, it was functional
> the last time I examined it, which was around one year ago. My machine was,
> likely still is, suffering from one malady that yours is not - my keys will
> not hold-down during long computations. As you might be aware, the keypad
> lock-out feature was implemented due to the fact that a talented keypunch
> operator could frequently get 'ahead' of the machine - which would result
> in errant output.
> Likewise, I have no service documentation for it. But if I can be of any
> assistance, so far as providing voltage / resistance / component readings,
> I'll try to do my best as time allows.
> They are fascinating machines - all the more amazing, considering that they
> were almost entirely designed by a single engineer.. save the analog /
> display portions, as I understand it.
This block diagram may help at least the discussion.

I'd try to trace back if there is any possibility of doing so, on the 
display matrix, or maybe the blanking.  Your display looks like the 
deflection is pretty much well adjusted, but the display matrix logic 
isn't working to scoot the beam around when it counted to the position 
of a digit.

Maybe try scoping with care to see how the input to the CRT on the 
display drive works.

Hams broke up a huge number of these calculators in the past to harvest 
just the CRT and junked the rest.  I got my three from a guy who had 
been a singer / friden service guy, and beat out a number of hams 
answering a classified ad for his sale.  The CRT may be a well known 
commodity if you can find it, or know some older hams who might know who 
to ask.  ISTR there was a sheet on how to hook them up.

(OT) Sorry, Al, he had a lot of documentation, but I was not in collect 
everything mode then.  It was all for the take free., and he had a test 
machine in his living room (Singer system with a 10 platter drive.)  
Rare to unknown now days.

Nice find.
> On Sun, Feb 1, 2015 at 10:23 PM, Kyle Owen <kylevowen at> wrote:
>> A friend of mine gave me a Friden EC-130. It's in pretty good shape, though
>> it's missing quite a number of screws, as well as the bottom plate.
>> Pictures here:
>> As you can see from the pictures, I don't get any distinguishable digits on
>> the CRT. Thankfully, most of the logic does seem to be working; entering
>> too many digits before the decimal place as set by the rotary switch
>> results in an overflow upon hitting enter. Entering thirteen 9s and
>> dividing by 1 takes about 2 seconds (the button stays depressed; quite
>> cool), whereas simple adding and subtracting returns the result right away.
>> Keyboard feels good, and you can see the CRT modulate differently depending
>> on what's to be displayed.
>> I've tried the obvious thing of reseating boards and rotating the pots back
>> and forth a bit, to no avail.
>> My understanding is that schematics are not available for the unit. Is that
>> still correct? It wouldn't be a hard unit to reverse engineer; it's just a
>> whole lot of components.
>> If anyone has any advice to offer, it would be much appreciated.
>> Thanks,
>> Kyle

More information about the cctech mailing list