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Old 11-23-2016, 01:30 PM
madlabs madlabs is offline
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Eico 633 CRT tester, operation question

Hi All,

I want to use my Eico 633 to test a 21FDP4 I just picked up. Right underneath the settings in the manual it says "connect jumper between pins 2&6". It isn't appended next to the 21FDP4, but below it and centered like this:

21FDP4 - data in line here
Connect jumper between pins 2&6
21FAP4 = data in line here

As it happens I want to be able to test a 21FAP4 as well. The way I would read this would be that tubes listed under the connect jumper line would have pins 2&6 jumpered to test. So 21FDP4 no jumper, 21FAP4 with jumper. Is this correct?

And if one did get it wrong and jumpered one you shouldn't or vice versa, would any grief causing destruction ensue?

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Old 11-23-2016, 05:45 PM
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Tubejunke Tubejunke is offline
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Sounds like you are reading the manual right. I got out my Sylvania Technical (tube) Manual from 1958 to look up the pin configuration for the tubes. I could only find reference to the 21FDP4 and it only uses pins 1,3,4,6,7 & 8. No #2 there to worry about causing destruction by mis-jumpering .

There may be a physical pin #2 on your tube, but it has nothing connected internally. No worries there. Pin 6 on this tube is the G2. I don't know how similar the two tubes are, but this information at least confirms your interpretation of the book is correct. I wonder if the AP4 is electrostatic focus and

By reading my book it looks as if what you have was the cutting edge of technology in 1958. There is a whole list of "perks" if you will to each tube listed. This one is "light weight, extremely short, 1 1/8" gun diameter, no ion trap etc. The descriptions remind me of those really shallow sets I used to see quite often in smaller homes when I was a kid. Heck, it didn't look like there was more than a foot and a half or so of cabinet top. They looked to be from the early 60s and were always black and white. Sort of odd looking frankly. They were marketed I believe as "space savers." They did do that, but often looked easy (and tempting) to topple over.
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
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Old 11-24-2016, 10:12 AM
madlabs madlabs is offline
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Thanks for the confirmation. As a TV noob, don't want to do something that ends up with me crying. I ended up connecting the CRT to a set and it works OK, it's a little brighter that my 21EAP4. I think with a little on time it will do OK. Now I'll also test it with the Eico and see what it reads.
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