CBS Columbia b&w

[timmy]

Since I got this set done works nice but when it’s turned on and the picture comes on it’s mostly white like the contrast is not there until about a minute later the picture darkens and looks good any quick ideas what may be the culprit.

[Yamamaya42]

Originally Posted by timmy

Since I got this set done works nice but when it’s turned on and the picture comes on it’s mostly white like the contrast is not there until about a minute later the picture darkens and looks good any quick ideas what may be the culprit.

Most likely a tired picture tube, with poor cutoff, which slowly gets better as it warms up.

[timmy]

That was one thing I thought of but I don’t remember how good the cutoff was I would have to test it again.

[timmy]

So I noticed the focus is lousy when first turned on and I see there is an ion trap and a focus magnet would that be the rings on the neck one for centering and the other for focus ?

[init4fun]

Originally Posted by timmy

So I noticed the focus is lousy when first turned on and I see there is an ion trap and a focus magnet would that be the rings on the neck one for centering and the other for focus ?

If the focus gets better as it runs, I'd leave the adjustments alone. If you adjust it to look good when it's first turned on, wouldn't that make it look worse as it warms up, VS better?

[zeno]

Sounds like the classic soft CRT.

[timmy]

Originally Posted by zeno

Sounds like the classic soft CRT.

Soft ??

[old_tv_nut]

Originally Posted by timmy

Soft ??

"Soft" is a way of referring to a worn-out cathode, so when the video highlights try to draw more current it doesn't provide as much current as it should and makes the spot bigger and out of focus.

[timmy]

So I guess this crt is not soft as we thought I put the tester on it and the needle bearing moved so I did the remove shorts just a quick touch of the button and a little spark inside and immediately the needle jumped up to 500 on the scale which only goes to 600 I didn’t try it yet but I’m sure focus and contrast is good. The cutoff tests excellent so I’ll see shortly. Tin whiskers inside I guess don’t know how these shorts form.

[timmy]

Anyone have a ge crt code book to see what year this tube is 6113 is the code

[old_tv_nut]

Don't know aboout GE for sure, but some makers' 4 digit codes are year and week, so 6113 could be 13th week of 1961.

https://www.ecianow.org/assets/docs/...g%20Format.pdf

[timmy]

This Columbia won’t pick up air waves with an antenna but cable wire works fine it has an agc pot and if that is far out adjusted would this keep it from accepting the antenna signal. All my other b&w sets work with a cable wire and an antenna in house except the Columbia makes no sense