[TinCanAlley]

Originally Posted by DaveWM

Perhaps this has been asked and answered but will bring it up.

I presume the jail bars are caused by either of the below:

video info (lack of blanking during retrace)

video info (ringing happening during trace)

non linear sweep during trace (not likely) if this was the case I would think holding the scope prob near the horz leads of the yoke should give a wave pattern that would have the ringing during the rise time, but that is just a guess.

Did you ever try putting on a blanked out screen and scoping the G1's (and may was well look at the cathodes and G2 for that matter, even though they should not have video info).

with an blanked out screen you should have no AC signal at the G1 (or cathodes and G2 for that matter).

You should adjust the brightness and contrast on the blank screen to make the jail bars as bad as possible.


This should be done with a blank screen image being fed to the tuner so you can see the horz sync pulse (the blanking period) followed by a burst pulse.

If there in no AC signal between H sync pulses, then is seems it would HAVE to be insufficent blanking during retrace.

If that's the case I would still be hung up on how you have the brightness/contrast/screen drives setup. I think this is the same set that you said you could not get the CRT setup done when using the described SAMs method using the setup switch and G2 adjustments.

You are correct. I am unable to get any drive other than blue to produce a faint line in setup. The other two don't show up at all. Well, they might if I could completely black out my room (guess I could try it at night). Still, if the line doesn't show up in a dim room, that not normal, right?

I had to pull the IF and adjust the G2s for a dim raster. Checking the voltages, they are within the range noted by Sams.

My new pattern generator allows me to pretty much blank everything out and just leave the jail bars (IQW off, chroma off and luminance off).

So I should pull the socket back a bit, put the probe's j-hook on each of the G1s and the cathodes. My scope is not designed for the voltage found on the G2s and I don't have a HV probe.

As for the ringing around the yoke, I see a ringing type pattern in that whole area, especially the focus wire (just having the probe near, not touching). I don't know if it's actual ringing or just a normal electrical field the scope is picking up. I'm attaching a pic of what the scope sees in the general HV area and around the yoke wires, focus wire and FB.