Mighty Monarch of The Air

[Electronic M]

Remember to use a plastic hex tool as not only will a metal one make it harder to adjust right, but it also can crack the slug (and that is quite bad).

[old_coot88]

Originally Posted by vts1134

.
What do you thinks happening on pins 4 and 5?

Pins 4 and 5 are the grid and plate of the oscillator, respectively. They carry a high level, complex waveform which causes a digital meter to go nuts. The voltages are probably OK since the oscillator is obviously running very robustly.

[vts1134]

The horizontal afc is a easily adjustable. This is what I adjusted to get the high side of pin 1 to -1.8. I can adjust it from end to end without any problems (it's a screw tip btw). I cannot seem to lock in the picture no matter where it is though. I am adjusting it in conjunction with the horizontal hold control. I traced most of the capacitors that I replaced in that area and couldn't find one I missed, or misplaced. I'll try to get to the rest of them today. Is there another method to use with the horizontal afc besides turn it until you get a picture?

[Electronic M]

I believe that the AFC tries its darnedest to keep the horiz in synch when it is slightly off frequency. However if it is badly off frequency the AFC can try as hard as it likes and will still fail to make the horizontal sync up. I think you will get better results adjusting the horizontal frequency rather than the AFC.

[old_coot88]

Originally Posted by vts1134

The horizontal afc is a easily adjustable. This is what I adjusted to get the high side of pin 1 to -1.8. I can adjust it from end to end without any problems (it's a screw tip btw). I cannot seem to lock in the picture no matter where it is though. I am adjusting it in conjunction with the horizontal hold control. I traced most of the capacitors that I replaced in that area and couldn't find one I missed, or misplaced. I'll try to get to the rest of them today. Is there another method to use with the horizontal afc besides turn it until you get a picture?

First off, don't be too concerned with the voltage readings on pins 1 and 3. They are at very high impedance, and your meter puts lighter loading on the circuit than the original meter did. Thus you get higher readings than the original meter gave.
In your last vid, it sure looks like the fine tuning adjustment is off. That's the outer shaft concentric to the channel selector shaft. Have you tried turning that stop-to-stop? Once the signal is tuned in properly, it'll be a lot easier to see what's going on with the horizontal.

What channel are you using to feed the signal to the set? Just on the chance that the tuner's tracking might be off, try clicking one channel higher and one channel lower, and fine tune stop-to-stop, and see if you can see a recognizable pattern (even with the horiz. frequency still off).

[vts1134]

Originally Posted by Electronic M

I believe that the AFC tries its darnedest to keep the horiz in synch when it is slightly off frequency. However if it is badly off frequency the AFC can try as hard as it likes and will still fail to make the horizontal sync up. I think you will get better results adjusting the horizontal frequency rather than the AFC.

I thought that the Horizontal AFC was the horizontal frequency adjustment. Is there another adjustment that I'm missing?
Adjusting fine tuning, horizontal hold, and horizontal afc the picture below is as close as I can get. The pattern should only be three vertical white lines on a black background.

[old_coot88]

Originally Posted by vts1134

I thought that the Horizontal AFC was the horizontal frequency adjustment. Is there another adjustment that I'm missing?
Adjusting fine tuning, horizontal hold, and horizontal afc the picture below is as close as I can get. The pattern should only be three vertical white lines on a black background.

Well, AFC stands for "automatic frequency control" which is the function of the first section of the tube (the second section being the oscillator). The AFC section takes the sync signal and compares it to the oscillator's signal and then automatically adjusts the oscillator up or down to lock it to the sync signal. (The 'horiz. hold' control {R7} adjusts the locking range of the AFC).
Anyhow, the oscillator should be running at 15.75khz. If the oscillator is 'waay off but running at some integer of 15.75khz, the AFC section can lock onto that. And that's apparently what's happening.
It's hard to tell from that screen photo if the osc. is running above or below the correct frequency. The oscillator's frequency adjustment is that coil B1. Adjusting B1 should bring the osc. to the correct frequency unless something's seriously out of whack.

[vts1134]

So B1 IS the afc and adjusting it adjusts the horizontal frequency?

[old_coot88]

Originally Posted by vts1134

So B1 IS the afc and adjusting it adjusts the horizontal frequency?

B1 adjusts the oscillator's frequency.

B1 is not the AFC.

The term AFC (automatic frequency control) is a bit misleading as it's used here, because it does not control frequency; it controls locking action, locking the oscillator to the incoming sync signal once the oscillator is close enough to be "grabbed" and locked in. A better term might be "automatic lock control" or "automatic hold control".

As mentioned before, the oscillator can be running at an entirely different frequency and still be grabbed and locked to the sync signal, which appears to be the case in that last screen shot.

[vts1134]

A bit misleading indeed. At any rate, the last picture I posted was as close as I could get through adjusting B1. Something else must be outa whack. I've checked the connections in and around the horizontal oscillator and sync tubes, nothing jumped out as misconnected or wrong. I also swapped out the horizontal oscillator tube for good measure.
So close yet so far.

[old_coot88]

What about the 8.2K resistor (R81) which parallels the B1 coil? Have you verified its value? And the 330pf cap (C57)? Could it possibly have been replaced with a different value?

Any chance you could post a vid of the screen while turning the B1 adjustment all the way in and out, while narrating what you're doing? This might give a better handle on whether the osc. is running too high or too low.

BTW, you're also trying the horiz. hold control (R7) along with the B1 adjustments, right?

Does the genny's three-stripe pattern display correctly on another TV?
Or better yet, can you feed the Majestic with actual program material from something like a DVD player or a VCR?

[vts1134]

R81's value is on target.
I've got the video below. It starts with the slug all of the way "out." I found that I could adjust the slug a bit more after the end of the video and when I did the picture looked a lot like it did in the beginning of the video.
http://www.youtube.com/watch?v=74tfWbkOgH0
Just out of curiosity, for those of us without super human horizontal frequency identification vision. Would measuring the frequency of the oscillator be something I could use a scope for? I don't have my probe yet so I couldn't do it now, but it sure seems like that'd be something I'd use it for in the future.

[old_coot88]

Originally Posted by vts1134

R81's value is on target.
I've got the video below. It starts with the slug all of the way "out." I found that I could adjust the slug a bit more after the end of the video and when I did the picture looked a lot like it did in the beginning of the video.
http://www.youtube.com/watch?v=74tfWbkOgH0

It looks to be spot-on at :02-:06, :09-:13, :19-:21, :26-:30, and :35-:37 in the vid. Set B1 back to where you had it there. There appears to be nothing wrong with the horiz. frequency. But the fine tuning is still off. The set wants to make a picture when the signal is tuned in properly. Are you turning the fine tuning stop-to-stop? On the chance the tuner's tracking might be off, click the channel selector to the next higher channel and try the F.T. stop-to-stop. Then try the same thing one channel lower. If the VCR is outputting on Ch.3, try it on Ch.4 (or vice versa).
The vert. hold is also gonna need adjusting when the pic is tuned in.
Yer aaaalmost there.
oc

[vts1134]

I've tried fine tuning the signal as much as I can and I still can't get it any better. I changed the output of the VCR from channel 3 to 4. When I changed channels up and down away from the modulated channel I noticed that when I was one channel lower I got strong audio but not picture. One channel higher gave me neither sound nor picture. Maybe I'll take the tuner apart and give it a good cleaning. I did notice some things tonight that I thought I'd share. The set can only lock onto a picture when the horizontal frequency slug is 1/8 of a turn from completely out or 1/8 of a turn from completely in. When it is in that position, although the picture locks on, the horizontal does not fill the screen. I removed the resistors we had in place on the horizontal output tube to reduce voltage to the 1X2 to see if that would A. bring the picture back to full horizontal and B. cause the 1X2 to spark again now that the frequency was so different. It did succeed in making the horizontal size increase somewhat, although not back to full screen. The set is now also back on full line voltage without the additional resistors on the horizontal output tube and there is no sparking problem in the 1X2. I also went back to the video generator to see if I could get the set to lock on to a pattern now that the horizontal frequency is where it wants it to be. I injected at the point where M4 would connect. After much adjustment the picture below is the best that I could tune it in.

[Electronic M]

Looks good on the horizontal synch/frequency front, but the vertical probably needs some work.
I'd say you're within spittin distance of getting a watchable picture.