[bergfex]

Hello, is it possible to adjust akb? The blue tube of my 1270 started to flicker and now its running on maximum brightness. This looks really ugly! Shorting pins CF2-2 reduces brightness of blue to normal. The crt is in good condition with no burn visible and there is no reason for akb to push up brighness to max. Can this be adjusted instead of deactivating akb?

 

[Tim Smith]

Did you try to adjust the G2 setting of the blue tube?

 

[bergfex]

Yes, I disabled akb and did the G2 adjustment (this was recommended - thread in HT-forum). But after removing the jumper akb (as I think) forces the blue tube to run maximum brightness. Even setting bias and gain to min (blue) gives me a blue screen instead of black.

 

[Genocide1]

do a picture funtion reset first

Turn all the g2 controls all the way down

put a jumper on the cf2 board

pull up the pluge patter and adjust til u can just barely see the gray box on the right. If you see the black box my guess is your tube is blooming at that point


turn slow or fry the tube

 

[Tim Smith]

Sounds like you need a tech to come out and look at it or just perminently disable akb.

 

[bergfex]

Thank you all, I'll try it again and do a reset and new adjustment of G2 settings. And- look for a nice jumper fitting into CF2-board. It's better than fry the tube.

 

[bergfex]

Yesterday I had enough time to play with my pj. I don?t know how to do a picture function reset. But I adjusted the pluge patter until I got slightly shining white boxes on a beautiful black background. Removing the jumper increases blue brightness and finally I adjusted with AKB on. The blue tube has NO akb-scan-lines, red/green have! It?s crazy. Does anybody know, what the reason is? Can I use akb on only two tubes, or is it better to disable it completely? May this cause problems with greyscale?

 

[Tim Smith]

Let me preface this with, I'm not a technician. But it might be a bad CB board attached to the blue tube. Maybe you could attempt to switch the CB board with one of the other tubes to determine if that is the problem. If it is you could probably just replace the board.