Played with a "7aa" today.

[rca2000]

Today, I played a little, with the ctc-7 set, that will soon(hopefully) be mine. in the past, I had checked the crt, to determine its integrity, on a tester. The tester showed it was in very good condition, but all I could get was a dim reddish raster from the set. It was stuck against a wall, and hard to get at.

NOW-- the set has been moved, and is where I can get behind it, and do some more thorough checking. SO-- I took the back off again, looked around a little, and then, plugged it in. same reddish raster, with compression on bottom, and stretched on top, before.

Took my meter, tested b+. 394v-- pretty good. (this one is a ctc7AA, with silicon diodes instead of 5u4 tube rectifiers.). Looked around, hooked up a makeshift antenna-- could get no sound, just a little hum, and noise, between channels. So I statred to wiggle tubes around a little, thinking some of them had bad connections, or such.

Then, I noticed that the 6aw8 tube looked dark, but was warm. I pulled out the tube-- DEAD!! White getter!! Now, I am a little more excited. SO I began looking foor one, I could only find an 8aw8 at this shop. I put it in anyway, hoping it would warm up enough, to work somewhat.

Well-- the tube DID warm up enough, to give sound, and now, there looked to be some video in the picture. I played with the grey scale a little, and was able to get white. (the CRT a 21cyp22, has a 63-37 date code on it). NOW-- I can ALMOST see a picture, and have sound, albeit a little weak and distorted.

SO-- here is where the set is at-- GOOD CRT, fly, and major parts. The channel indicator, which should show through the front, is missing. I can get some sound, and video, with color, BUT-- I could NOT get the horizontal to lock, It would go into "christmas tree" when I tried to advance the hold control, to get it synced. Is this anythnig to do with the under-voltage on the 6aw8? it looked like it was part of the IF, or low-level video ckt.

OR-- is this ,more likely, because I need to recap the set? I am SURE some caps need changed. The "picture" is compressed, but the brightness is not bad. ALL 3 guns seem to be pretty strong.

After all of this, I returned the set to its "prior" condition, so as not for the owner to see the potential it has-- he assumes the CRT is not too good, and I do NOT want to change his mind on that fact!!

[Steve K]

Jack:

There are a number of 6AW8s in the 7 chassis but even if bad should not cause the horizontal problem. Of course it could be a horizontal tube causing the problem but if you do get the set you will want to recap the horizontal and vertical boards for sure.

Steve

[Bill Cahill]

I reccommend re-capping entire set. Further, if silicon diodes are of old "hat " type, I'd reccommend complete replacement. They are leaky, and tend to suddenly short for no apparent reason. Also, check all electrolytics carefully. They also have a 350v cardboard capacitor used in vert. circuit, mounted on middle board. That one always crapps out.