RCA 14-S-7070 Vertical Problem

[rwilson]

After a recap I have this. The top part change linearity along with the brightness. There are still a few adjustment problems but this is the main problem. This is only my 2nd rebuild and not sure where to look.

Bob

[Notimetolooz]

The brightness control changes the cathode bias on the CRT.
The linearity control changes the grid bias on the vertical output.
The two should be unrelated, however the two circuits are fed by the same 240V supply. I can't see how the brightness control would change the supply loading unless you got something shorted or mis-wired. However the linearity
could effect the CRT brightness by changing the supply loading. Did you try a new vertical output tube?

[Eric H]

Do your height and linearity controls have any effect?
Sometimes you have to adjust the picture centering rings so you aren't trying to adjust the linearity to fit an off center raster.

Did you replace all the electrolytic capacitors?
Did you check all the resistors in the Vertical circuits?

[kvflyer]

Originally Posted by Eric H

Do your height and linearity controls have any effect?...

I had an issue with an Admiral that I restored. It worked well but then, a snap and the vertical linearity control had no effect. Long story short, tin whiskers in the control. A good brushing and cleaning fixed it.

It took a while to figure that one out, for me.

[rwilson]

I replaced the vertical output tube with no change.
The centering rings do not change it all that much.
There is a lot of interaction between the three vertical controls. I cannot achieve full vertical height. When I try to adjust it to fill the screen I lose vertical hold and the control does not have enough range to lock it back in.
I have a B& K 1077B. Would I prove anything by using it for vertical drive?
Maybe I should check capacitor values closely again to make sure one is not the wrong value. Of course with this set I have to pull the CRT out to gain access to much of the circuitry.

[Eric H]

Check all the resistors in the vertical circuits, at least one of them is a 5% tolerance. Some of the caps are odd values and the close enough standard values may not be close enough.

[JohnCT]

Originally Posted by rwilson

There is a lot of interaction between the three vertical controls. I cannot achieve full vertical height. When I try to adjust it to fill the screen I lose vertical hold and the control does not have enough range to lock it back in.
I have a B& K 1077B. Would I prove anything by using it for vertical drive?

There is generally interaction between the vertical adjustment controls. I'll never forget the first time I adjusted the height on an early XL-100 (solid state) and was amazed that it had perfect linearity (no lin control either) and the linearity didn't change no matter where the height controls was set for. Before solid state, it was always a dance between the three controls to get proper deflection and centering, while trying to keep it more or less linear.

Yes, with the 1077B you can drive the yoke directly, then move back and drive the vertical output transformer to see if that's OK.

John