Re: Friden EC132 needs help!

From: Rick Bensene
Email: oldcalc at bensene dot com


Hello, When you say that you replaced the CRT on the 132 after the original was broken, did you replace it with the exact same type of tube? Replacing it with a 'close' replacement could cause problems because the high voltage supply in the 130 and 132 is pretty much designed around the CRT. A CRT with different high-voltage requirements could load down the high-voltage supply, which is derived (through multiple stages of switched capacitor voltage doubles) from the main logic supply. Dragging down the high voltage supply can cause problems with the main logic supplies, which will make the machine act weird. Unfortunately, there isn't much material out there on the insides of these machines. There are some patents that reference the general architecture of the machine, and examples of logic circuitry, but I've found nothing as yet in the way of service documentation for the EC-130 or EC-132. You didn't give much details with regards to the symptoms of the malfunction. With some more details, it might be more possible to make some educated guesses as to what might be out of whack. Regards, Rick Bensene The Old Calculator Web Museum http://oldcalculatormuseum.com