Picked up and Admiral 20X122

[Bill Cahill]

Lucky guy. I have an imcomplete one that I got working, and, it broke down. They do show a very nice picture.

[Doug66]

I've got too many other TV projects going now to start on another, but I couldn't resist the urge to pull the chassis out of the cabinet and have a look. It appears unmolested. I think I can only see one capacitor that's been replaced during the life of the set.

I'm waiting on parts for my Hoffman, and just about to finish up my Emerson portable with the picture jitter; so I may go as far as replacing a paper cap or two in this Admiral before I set the chassis back in the cabinet.

[Doug66]

I didn't have anything to do yesterday, so I decided to start recapping this set. I've got most of the paper caps replaced and 2 of the 3 electrolytics done.

I'm still getting good sound but no raster. My HV probe shows only about 1KV of HV I started checking voltages in the horizontal section and found them way off.

V15 the 6BG6 is as follows 6SN7 Horiz Osc V14
Pin SB I have Pin SB I have
1 -.5 0 1 -3.1 -10
3 9.6 2.4 2 100 38
6 190 105 3 -18 -6
8 260 221 4 -55 -24
5 190 120
Have tried another 6SN7 and another 5U4.

[Doug66]

My voltages got messed up when I posted, so I will redo it.

6BG6 Pin 1 SB -.5. I have 0
Pin 3 SB 9.6 I have 2.4
Pin 6 SB 190. I have 105
Pin 8 SB 280. I have 220

6SN7 Pin 1 SB -3.1. I have -10
Pin 2 SB 100. I have 38
Pin 3 SB -18. I have -6
Pin 4 SB -55. I have -24
Pin 5 SB 190. I have 120

[Doug66]

Ok, I have replaced everything in the horizontal osc & output sections with the exception of C71 (7.5pf @ 1500V) and the 500pf doorknob cap. I still have no high voltage. Most positive DC voltages on both the 6SN7 and 6BG6 tubes are way low except pin 8 on 6BG6 is right (about 270V). I have no negative voltage on the grid of the 6BG6. Replaced R78 and R79 and C54. I don't hear the horiz osc running and adjusting the horiz drive timrrer screw has no effect.
Any ideas?

Thanks
Doug

[Doug66]

I finally got a picture this morning. A 75K ohm resistor in the horiz osc circuit was open. I'm getting a good pic now but with vertical issues. It looks like I'm getting a double pic and it will not fill the screen vertically. I'll keep poking at it.

[Kevin Kuehn]

Originally Posted by Doug66

I finally got a picture this morning. A 75K ohm resistor in the horiz osc circuit was open. I'm getting a good pic now but with vertical issues. It looks like I'm getting a double pic and it will not fill the screen vertically. I'll keep poking at it.

Your actually not too far from the correct vertical height. Keep in mind that the top and bottom of the CRT should be covered by the mask for a 4:3 aspect ratio.