I just cant see it being the coil, but cant hurt. so the centering rings did not do the trick? you cant adj the horz and get rid of the blanking bar and then center the pic?

I can adjust the rings til almost all of the bar is gone, but the pic still is not centered. I'll play with those rings again tonight. Like you, I really can't see it being the coil. However, sometimes I can bump or wiggle the adj shaft on the coil, and the picture jitters. That's what's leading me towards the coil.
At times the set will play for over an hr and not mess up except the pic won't be centered. Other times the horiz is so unstable, it loses sync every 15 sec or so.

Doug

but can you see another pic far side of the blanking bar?, when its not centered that is.

Dave, I just took 4 pics of the set playing so you can see what I'm facing. Upon firing it up this afternoon, the horizontal was VERY unstable; almost impossible to lock into sync for more than 30 sec.
Image 1 is a commercial, and you can see the lettering is cut off on the left, but the pic is stable.
Image 2 is a show on Amimal planet, and the Animal Planet logo in the top right needs to be over farther to the right thus showing the pic is centered too far to the left.
If I adj the horiz hold to move the pic to the right, it loses horiz sync. Turning it to the left slightly produces Image 3 then eventually Image 4.
If you look closely at Image 1 (commercial) you can make out the bar at the extreme right of the screen.

Doug

Three things come to mind.

You could have a tube making a poor and intermittent connection with it's socket.
You could have a tube with an internal bad connection.
You could have a resistor with an internal fault that causes the resistance to fluctuate erratically.

Try gently wiggling tubes with the set running and see if wiggling one causes the sync to jump around.
Then try gently tapping tubes with a plastic screw driver handle and see if that causes the sync to jump around.
Get some freeze mist (I think that Radio Shack may carry it) and cool down the resistors and other parts looking for a change to the sync.

Will Do Tom.

I have a can of Freeze Mist, so I'll utilize that tonight. I did find another 12CU5 tube for the audio B+ as you suggested, but that didn't help any.

Regarding the 130V source, have you checked R43? Does the 255V source show up shortly after power up? Any broken solder joints on that circuit board?

We need to go back to basics here. When you replaced C3 and 4, did you use the same values? This is your 130 volt source that is derived from the 255 source. The 255 volts has to be correct, and stable. If it changes with the brightness or volume, then your selenium rectifiers are bad or the filtering caps are bad (or R83 is flaky).

Changing the values of C3 or 4 is not a good idea. Is R43 OK (330 ohm)?

Do you have a power supply capable of subbing the 130 volt source?

Guys, thanks for the tips on what to check. Here is what I have come up with. I just replaced R83 since I had another one. The 255V climbs up to about 268 then drops back to around 255. R43, the 330 ohm acutally measures around 410ohms. I assume that's too high. C3 is exact when I replaced it, but on C4, I used a 47 instead of a 40. Do I need to go back down to a 40?

The 130V still drops as I increase the vol unti the set has played for several min.

Doug

I would find out first why the fine tuning isn't working.

Electrolytic caps used as filters can be replaced the next larger available value without any problems.

The 130V dropping with increased volume sounds like a weak audio output tube. If the other tube that you tried is a used tube, both could be weak. But if it stabilizes after a few minutes than this should not be causing problems after the warm up.

The 255V climbing to about 268 and then dropping just sounds like the set is not drawing quite as much current from the power supply at first as it does later. As with the audio output tube, tubes can take a few minutes to draw the full current that they are supposed to.

I just restored an Admiral 21F1 Chassis. After recapping it, I powered it up, and had unstable synch horizontally and vertically. I replaced the synch tube, and presto, stable pic.

When it comes to checking and replacing resistors that have drifted upwards or downwards somewhat, I find that it usually does not make much of a difference. Unless the circuit calls for tight tolerances (like a 5% resistor) It's usually something else simpler, like a leaky mica cap or a bad tube.

After recapping, I usually swap tubes in the affected circuit as a start. Cleaning sockets with DeOxit, wiggling them, etc is a good idea.

After restoring 15 TVs, I've learned one immutable law: It's always something simple.

C64, C65, R81 assuming you have subbed tubes for sync and osc. looking for the feedback from the horz osc back to the AFC circuit to be at fault.

First let me correct some bad info that I gave. The fine tuning IS working now. When I got the set, it was missing all of the knobs. I had a set of knobs off a junked chasis, but until I dug them up I was using generic knobs. I guess the one I tried for the fine tuning was just too big for the shaft. Upon finding the correct knob, the fine tuning does indeed work.

I did replaced the 330 ohm resistor with a new one last night but no improvement.
I fired it up today and did some voltage checks. The vol still makes the 130V decrease, but I also found it makes the 255V Increase. At max vol, the 255V reads 270V.
The set is playing now (been playing for about 10-15 min). The 130V reads 170 with no vol. With vol mid way it reads about 155. Max vol reads 123.
At startup (just as the pic comes on) max vol is around 50 volts or so. No vol is around 110. At the set plays the B+ slowly increases.

Tom, I just ordered 2 new 12CU5 tubes.

I still want to lean toards the horix hold/freq coil. I studied my 1956 edition of Sams "TV servicing guide", and that sympton is listed the AFC troubles. However, all the examples they use are more complex sets with an AFC tube instead of a simple circut like mine. However, it did say that one possible cause was a bad coil. The coil is located towards the center of the set (from front to back) and is attached to a long plastic shaft reaching all the way to the backl of the set. Everytime I even bump that shaft, the pic jitters or loses horioz sync. I've got a new coil ordered, and it SB here tomorrow or Sat. I'll put it in my jumper wires and see if that helps before permnently installing it.
Doug

Did you substitute the tubes in the horizontal section with those from one of your sets that is working?

Dave C65 was replaced when I 1st started working on the set. C64 checks fine in my Eico checker, and R81 (33 ohms) reads about 40 ohms.

I do have spare tubes for 6CG7, 6BA8, 5U8, and 12DQ6, but subbing doesn't help any.

Doug

I have just discovered something. On the 130V B+ line, I disconnected the wire going to Pin 8 of 6BA8 Video output tube. Upon 1st applying power, the B+ is still low and climbs, but it is 10V higher with that wire disconneted. While it's climbing 106V with the wire disconnected would be 96V with it connected. Discoinnected kills the pic and audio, but turning up the audio to max does not cause the B+ to fall.\

I checked the voltage on the plate of that tube too. It SB 155V. With that B+ wire connected to pin 8, I have 251 on pin 9. Disconnected I have 279V.

Doug

Check the high voltage caps in the deflection windings, and then work back.

Well I stand corrected. The horiz coil came intoday. I hooked it up with jumper wires, but it didn't make any improvment. Upron trying to hook the wries back up to the old coil, I broke one of the lugs on the old one, so I decided it would be easier to install the new one permanently rather than attempt a repair on the old one.

Blustar1 I also went back and replaced the high voltage caps (C62,C63) in the yoke as well as the 2200 ohm resistor in that circut. No improvement there.

I've got one theory I'd like to run by you guys. It's been stated that my problem may not be originating in the horiz circut. As I said yesterday, when I disconnect the B+ from the 6BA8 tube, the B+ dropping problem seems to go away. I can't understand why I have about 255 V on the plate of the 6BA8 when I should have only 155. C31 (.1) has been replaced. That leads to 30V on pin 11 of the CRT which is what I have. The only other thing between C31 and the plate is L4 peeking coil. I'm wondering if that's may be the culpret?

Doug

a few questions, again its hard to diagnose with out being there.

1) does the vert lock in solid

2) does the horz allow you to flop the diag lines one way and then the other with a solid lock between flops (not the phasing but the lock)

3) have you tried different signal sources

4) you said you checked that one cap I mentioned, it was rated for 1kv voltage, did you test if for leakage at that voltage?