Dove right in! Help with RCA 21-D-8628

Originally Posted by Kevin Kuehn

If that is still a VHS player you're using for a signal source it could very well be your problem. It almost appears like a video tape not tracking. And the sync pulses are dependent on the head speed. Does the vertical hold control on top the TV have any influence on moving that black bar near the center screen up or down? I would suggest trying a DVD player though an rf modulator. You could probably even run the DVD player into an auxiliary input on the VHF player and still use it's rf output.

The vertical knob on top does very little as far as I can tell. The flicker doesn't disappear at all, no matter how often I adjust anything. I can hear the feedback in the speakers, the frequency of the hum and the flicker practically sync. Something is causing enough disturbance, and it isn't getting filtered or properly syncronized. Also- the horizontal lines stay no matter what.

I don't know enough to figure this out. Time for the crt to probably rest a bit.

I can hear the flickering in the screen without volume

[Kevin Kuehn]

Originally Posted by BandDirector

I can hear the flickering in the screen without volume

You've got a really strange problem going on there. Don't fiddle with this while the set is on, but how is the dag coating on the outside bell of the CRT? There should be some type of contact from chassis ground that presses against the dag so that it's grounded. The dag coating forms one side of your HV filter cap, the other side is a similar coating on the inside of the glass.

[Kevin Kuehn]

I drew a red arrow pointing to what "I think" is the dag ground contact wire that likely should have a tensioning spring pulling it taunt against the conductive coating. That wire should have some means of connecting to the chassis so that the outside coating is at chassis ground. If it's not grounded you'll have all sorts of bizarre artifacts because of the noise being radiated from the high voltage supply into the other circuits.

There is a wire bale around the bell of the tube, where should it ground to the chassis?

Is there an adjustment to increase the scanning rate of the screen, perhaps the sweep is too slow? Is sweep the same thing as saying scan rate? Someone said that earlier I think

[Kevin Kuehn]

Ordinarily that wire would be connected to the CRT mounting hardware and then a wire would go between the hardware and some point on the metal chassis. I can't say exactly where on the chassis but it should be a secure connection using a lug under a screw. Hopefully someone that's more recently worked on one of these sets can shed more light on what that hookup originally looked like.

Horizontal hold controls the scanning frequency, and from your video it sure appears to be locked.

Originally Posted by Kevin Kuehn

Ordinarily that wire would be connected to the CRT mounting hardware and then a wire would go between the hardware and some point on the metal chassis. I can't say exactly where on the chassis but it should be a secure connection using a lug under a screw. Hopefully someone that's more recently worked on one of these sets can shed more light on what that hookup originally looked like.

Horizontal hold controls the scanning frequency, and from your video it sure appears to be locked.

Locked? And why can I not adjust vertical? The frame line is evident between DVD or VHS.

I cannot make the vertical fill the screen, there is a fold of the horizontal that appears to take up a small 1/3 of the bottom image. The fold disappears if I adjust the dual lugs on the vertical board. That creates hard, bright lines in the center of the screen or mid top, or mid bottom. There must be some other bad components?

[Kevin Kuehn]

Originally Posted by BandDirector

Locked? And why can I not adjust vertical? The frame line is evident between DVD or VHS.

I cannot make the vertical fill the screen, there is a fold of the horizontal that appears to take up a small 1/3 of the bottom image. The fold disappears if I adjust the dual lugs on the vertical board. That creates hard, bright lines in the center of the screen or mid top, or mid bottom. There must be some other bad components?

The horizontal and vertical have separate oscillators. One can be locked in without the other. I'm not sure what you mean by dual lugs on the vertical board. But besides that there's a difference between vertical hold locking in and being able to adjust size/linearity. With all the flickering I suspect some kind of electrical interference, which is why I've sidetracked to the Dag grounding connection on the CRT.

Back to the CRT dag grounding; With the set turned off take an ohm meter and check if there's continuity between the chassis and that wire that's suppose to be grounding the dag coating.

The bell reads around 450 ohms, the wire about half.

The lugs are below in a pic, I think they are verticals.

Discovery: Top (left) is height, bottom (right) is vertical linerity. I couldn't read the words until now.

Height will backtrack as I turn towards the extreme end, instead of continuing to the bottom or past bottom of screen.

[Kevin Kuehn]

Originally Posted by BandDirector

The bell reads around 450 ohms, the wire about half.

By half do you mean a 1/2 ohm, or 225 ohms? If 1/2 ohm you have a reasonable connection going to ground and you can cross that off as a problem.

Originally Posted by BandDirector

The lugs are below in a pic, I think they are verticals.

OK those controls are potentiometers generally refereed to as pots.

Originally Posted by BandDirector

Discovery: Top (left) is height, bottom (right) is vertical linerity. I couldn't read the words until now.

Height will backtrack as I turn towards the extreme end, instead of continuing to the bottom or past bottom of screen.

So how close are you to a full vertical picture now?

Originally Posted by Kevin Kuehn

By half do you mean a 1/2 ohm, or 225 ohms? If 1/2 ohm you have a reasonable connection going to ground and you can cross that off as a problem.

Nope, around 225 ohms. So I guess a bad connection to the bell, and bad connection to the chassis/ground?

The image will not fill the screen, but it will get close, leaves about an inch gap at the bottom.

[Kevin Kuehn]

Originally Posted by BandDirector

Nope, around 225 ohms. So I guess a bad connection to the bell, and bad connection to the chassis/ground?

The Dag coating itself will have resistance across itself, but from the chassis to the wire that contacts the Dag should be very low resistance. There's got to be a wire or sometimes a length of foil that makes that connection between the CRT mounting hardware and the chassis. I would think when you swapped chassis' that you may have run across it.

Originally Posted by BandDirector

The image will not fill the screen, but it will get close, leaves about an inch gap at the bottom.

And you still have the constant flicker?

[Kevin Kuehn]

If you have a clip lead(length of wire with alligator clips at each end), you could clip one end to the wire that contacts the Dag and the other to the chassis. If that makes no difference to the flicker then you can rule that connection out as a concern.

[Electronic M]

You see the silver rings with tabs pointing up and down on the back of the yoke?....Those are called centering rings and you adjust them by moving both tabs. The centering rings adjust both horizontal and vertical centering at the same time. When adjusting the vertical you have to juggle 4 controls: vertical hold(the user control near the tone knob), vertical linearity (inside chassis compartment), vertical height (near linearity), and centering....the goal is to get the most linear, centered image that fills the screen and doesn't roll...to do this you need a pattern of evenly spaced horizontal lines (which won't display even with the set out of adjustment as it is presently) preferably with some indication of the center of the video signal in the image. Then you adjust controls to center, even line spacing and fill screen on the TV (this may require going back and forth between each control repeatedly).