admiral 24c15 with 20b1 chassis attempt at restore

[old_tv_nut]

The horizontal sweep is not folding, but is stopping for a short time when the drive is misadjusted. What happens is that the flyback pulse occurs at the right of the picture, then the sweep current sawtooth for the left side of the picture comes from current reversing through the damper. If the reverse current ends before the horizontal output turns on again to make the right side sweep, the beam just stops in place until the horizontal output turns on. The correct horizontal drive waveform will turn on the horiontal output a short time before the damper stops conducting, so the sweep doesn't stop and there is no bright line.

If a flyback/yoke circuit could be lossless, the point where the line might appear would be centered left and right, but energy is lost in the resistance of the coils and by generating the high voltage, the energy left after retrace is less than was put in by the horizontal output, the left side sweep current through the damper does not last to the middle of the scan, and the horizontal drive has to turn on early and supply more than half the sweep, from somewhere left of center to the right edge.

[bandersen]

Beat me to it

[fumplet]

I guess IM just not seeing the point of horizontal drive if the adjustment needs to be basically tight to get rid of the lines, unless theres somewhere else to look. Drive is tight now and its a super soft line spread out about an inch almost not noticable. pictures still more left than it should be but I dont think thats fixable, other than focus coil messing with. I just need to hook up my scope which I suck at setting up, maybe that will get me on the downward slope of things. pictures definetly watchable but I really wanna understand this till my brain starts figuring this out on my own with out blowing up this tv.

[old_tv_nut]

Ok, I downloaded the schematic now.
I see the H drive is a variable capacitor. It would be interesting to know if the best setting is max or min.
Also: what components in the Hor. Osc and Hor. output stages have you measured or replaced?
Unfortunately the schematic I found has no voltages or waveforms - they would be helpful.

Have you adjusted the horizontal lock to get things synced with the horizontal hold centered?

I see that different valus of C419 are specified for different chassis. This seems to indicate that C419 and the attached capacitor C420 are critical.

[old_tv_nut]

Can you make parallel lists of resistors, capacitors, and tubes you have and have not tested or substituted in the hor. osc. and hor. out?

[fumplet]

I havnt messed with c419 or c420 which should be 330 and 270 pico farads. Quite possable that a few micas are bad. I have replaced the 6w4 with another one I had. 6bg6 replaced evilbay new. 68 ohm resistor on 6bg6 replaced. 100 ohm off 6bg6 replaced. All the paper caps replaced I could find. 1b3 replaced because the old one I saw orange on the metal disc below the hat inside of it that some said thats normal. 6v6 output tube on power supply replaced because it had a 6k6. also I do believe the 6ac7 and 6sn7. Also the sand resistor in series with the focus rheostat replaced. Focus adjustment sweet spot is sorta close to midway on rheostat so thats good.

[fumplet]

Dont remember if i adjusted horiz lock with the hold centered so i willl try that

[old_tv_nut]

Originally Posted by fumplet

Dont remember if i adjusted horiz lock with the hold centered so i willl try that

OK.
Then I would check all resistor values specifically in the Hor. oscillator and Hor. Output circuits. If no discrepancies, then I would try subbing those small caps or changing their value slightly to see if one fixes the drive line problem.

[bandersen]

Drive cap needs to be fairly tight. Most of the change is going to happen when it is very tight t0 snug. That's only about a quarter to half a turn. The tighter it is, the less drive signal you have. Too much drive and the horizontal output stage is pushed too hard and you'll get distortions.

Have you checked/replaced the 68, 82, 100 and 1M resistors on the 6BG6?

[Electronic M]

Delete.

[fumplet]

68 ohm replaced. 82 checked was93.4 and replaced. 100 was way out at 228 so replaced. 1meg was 448k replaced(under 1b3). 82 i might check again to be sure and other resistor under 1b3 was ok but should check alll again as test leads on one merer turned out to be intermittent

[Yamamaya42]

Originally Posted by Electronic M

Delete.

https://www.youtube.com/watch?v=CniafOgpiW8

[fumplet]

Well 82 ohm is now 84 instead of 93.4. Didnt seem to make a difference

[fumplet]

Bought new 6w4..which it is 6w4gt so i willl put that in sunday but other than that i dont know. Swapped in 6w4 i just had from other tvso if thats causing issues then the new 6w4gt should make a difference. Still think crt also might have something to do with it along with possable crt centering is more than one issue.
Ok I wasnt aware that the swapped in 6w4 the first time was actually a 6w4gt and I think it was also new. I know the schematic says too much focus coil adjustment then something else is wrong but whats acceptable tweaking of the focus coil to get left right center and still have focus equal all over the screen? I do know that when everything was super way out I had the center of the screen focused and away from center it was out of focus and I couldnt get both adjusting focus, but now that I made focus coil square to the neck of tube and no left or right or up and down tweaking, I could then get the whole screen focused. I need more knowledge tools to be able to figure this out.

[fumplet]

Checked resistors again. Found 1.8K cathode bias off 6k6 was about 2.4k and also a couple of the 47k were about 55k or above. Also the two 100k off of the 6al5 were 111k and 105k at 5 percent tolerance thats out so I replaced them. An alternate solution would be to shift the whole chassis in the wooden cabinet to the right and hog out all the knob holes, crude but effective. Strange things enter the mind when running out of options.