Dear fellow friends of vintage computing, I likely had the luckiest find of my years in collecting old electronic machinery this week: a Friden EC-132 in almost perfect condition. I took several days to open it up, remove the little dust it had and take some precautions before powering it on. To my extreme joy it works (almost) perfectly!!! What an amazing machine! I am absolutely flabbergasted by this wonderful piece of history.
However, of course there are two things that aren't quite perfect. Firstly, the "Overflow Lock" key light is not shining when engaged, but the functionality is there. I likely will not want to take the risk of replacing that. Secondly, and this is maybe where you can help, it only shows the result register or register 1. The CRT shows four lines or four numbers on the screen. The lowest is the result register and it is also the brightest. In my case it is the only one I see.
Initially, I thought this is a brightness thing. Through age voltages / brightness might have gone down and all I need is a dark room or more intensity. I saw nothing in the dark. I found the intensity & focus knobs on the inside in the CRT section (adjusting voltages for flyback). Adjusting there helped nothing so I tried to educate myself. There is a 400MB+ service manual available for the very similar EC-130 here https://www.oldcalculatormuseum.com/m-f130service.html It seems on page 126 of 161 they start to talk about how the display logic is and how the last line is the brightest. It turns out it draws 5 lines or more precisely it draws the last line twice and that is why it is brighter.
Unfortunately, this is where my expertise comes to an end. I can not comprehend the rest of the writing (FF N M P and all that). Neither do I know where to find this section in the physical machine. As I know there are many capable and helpful enthusiasts here, I ask for your ideas, please.
However, of course there are two things that aren't quite perfect. Firstly, the "Overflow Lock" key light is not shining when engaged, but the functionality is there. I likely will not want to take the risk of replacing that. Secondly, and this is maybe where you can help, it only shows the result register or register 1. The CRT shows four lines or four numbers on the screen. The lowest is the result register and it is also the brightest. In my case it is the only one I see.
Initially, I thought this is a brightness thing. Through age voltages / brightness might have gone down and all I need is a dark room or more intensity. I saw nothing in the dark. I found the intensity & focus knobs on the inside in the CRT section (adjusting voltages for flyback). Adjusting there helped nothing so I tried to educate myself. There is a 400MB+ service manual available for the very similar EC-130 here https://www.oldcalculatormuseum.com/m-f130service.html It seems on page 126 of 161 they start to talk about how the display logic is and how the last line is the brightest. It turns out it draws 5 lines or more precisely it draws the last line twice and that is why it is brighter.
Unfortunately, this is where my expertise comes to an end. I can not comprehend the rest of the writing (FF N M P and all that). Neither do I know where to find this section in the physical machine. As I know there are many capable and helpful enthusiasts here, I ask for your ideas, please.
