Ctc-16

[andy]

---

[Phil Nelson]

Originally Posted by DaveWM

with the pot pegged (its working just not enough range).

In my limited experience, if the pot moves but is pegged all the way, it's probably OK and there is some other problem. You can check the pot in place to get some idea of its value. Cleaning them can't hurt, but may not be a miracle cure.

If you want a laugh, you can read about my convergence fun at http://antiqueradio.org/RCACTC-11Television.htm .

I discovered about halfway through that my convergence board & assembly were for a later model than mine. I finally solved the worst problem when I found a hidden break in a wire to the green coil. It still isn't perfect, though, and probably never will be.

You are right to change only one thing at a time. Make sure there is a way to get back to Kansas if you change something and it gets worse.

Maybe it is the nature of this design that you can get the central area good, but may have to accept some kind of compromise at the farthest edges. It sounds like you're already very close, if you have only one problem at the bottom.

Phil

[Charlie]

Originally Posted by Phil Nelson

...but may have to accept some kind of compromise at the farthest edges.

Phil

I've read similar comments in a couple of old color TV books. If you can get good convergence over most of the screen, then you did good. With some sets, there will always be areas that you might not be 100% satisfied with. I guess you can say it's just the nature of the beast.

[DaveWM]

good read Phil. I think if I read enough it will become clear. Funny its like I am slowly coming up to speed on all this, must be my limited intellect, the fact that I need to read it over and over and over for all these concepts to stick.

what would be good is a VIDEO tutorial on the proper setup a set, from lineariy thru convergence.

[Phil Nelson]

I learn faster by doing something hands-on rather than just reading. One book I've found useful is the RCA Color Television Pict-O-Guide by John Meagher, published by RCA. I have the 1957 edition. It has great explanations of adjusting purity, convergence, etc. -- with lots of pictures! Many used copies are floating around.

Phil

[DaveWM]

I will keep an eye out for it Phil thx.

ok another session of convergence. I did tweek the blue center magnet, helped some. The picture is very good, I just need to stop looking at the grid, normal tv showing its very nice.

I am going to give it a break now, not sure if I want to mess with the diodes at this point. have to think about that. I still run out of bottom blue horz, but its closer after pulling up that magnet some. My color bars look funky colorwize but the flesh tones and normal viewing seems fine. Not sure what is going on there. I think I will start the filter cap restuffing next.

[DaveWM]

more pics, note the fuzziness is the cataract on the edge of the screen where the PVA has brokendown.

interesting how the old shows from the 70's (thats the hulk i think) seem to have faded in color.

Geez I want to watch Rockford but its so darn hot out in the garage, must be 90+ and its 10pm...

[Charlie]

Hey, that's looking quite impressive, Dave!

Loooking at that crosshatch and then looking at a normal picture... there's a big difference. You may not notice certain things as quickly just watching normal video.

We try very hard to get things just right on these sets. Most other people wouldn't even notice if something was off a little.

[andy]

---

[DaveWM]

I still have not tried the purity setup, I know that is suppose to be the 1st thing, guess I am just a bit nervous about pulling back the yoke.

I am still wondering if those diodes could be part of the issue. I have not studied the schematic, but if they are there to rectify the currend from the secondary of the vert output, and if they are weak, then maybe the magnetic field is not as strong as it should be. Again just guessing I reall dont have a clue as to what is going on in the convergence circuit.

Also have a real tough time with linearity, both vert and horz are way off.

I did not see a horz linearity adj, so figured I would start with checking the horz osc/damper/HOT for starters.

The vert is tough also cant get it to fill out the screen unless I mis adjust the vert linearity. I think maybe its a vert centering adj that needs to be done, to bring it all down 1st. Need to look over the set instructions again.

[Bill R]

Originally Posted by DaveWM

I still have not tried the purity setup, I know that is suppose to be the 1st thing, guess I am just a bit nervous about pulling back the yoke.

I am still wondering if those diodes could be part of the issue. I have not studied the schematic, but if they are there to rectify the currend from the secondary of the vert output, and if they are weak, then maybe the magnetic field is not as strong as it should be. Again just guessing I reall dont have a clue as to what is going on in the convergence circuit.

Also have a real tough time with linearity, both vert and horz are way off.

I did not see a horz linearity adj, so figured I would start with checking the horz osc/damper/HOT for starters.

The vert is tough also cant get it to fill out the screen unless I mis adjust the vert linearity. I think maybe its a vert centering adj that needs to be done, to bring it all down 1st. Need to look over the set instructions again.

Stop. Take a deep breath. Be patient. It will be good.

Convergence depends on multiple things being right. You should not (without lots of experience) try to do it out of order. Each adjustment interacts with the others. You must get purity first. That will put the yoke in the proper position as well. A slight movement either way may be just what you need to get the proper range on the convergence controls.

Then you do the static center convergence. This is what Phil was refering to by turning the blue magnet. You adjusted it and that helped, but you should pull the bar completely out of the assembly and turn it around 180 degres and reinsert it. That may help it bring blue back in range. When the center convergence is right none of the magnets should be at either end of their range. If they are you will have a hard time with dynamic convergence.
At this time go back and check purity. If it is still good move on. If it is off a little start over. Center convergence can impact purity, but not as much as purity affects center convergence.

When you do the dynamic convergence sometimes the lines will converge in the center, but not at the edges, or they will converge at the edges and center will be off. When this happens adjust the controls to make the lines straight. Then start over. Purity, then center convergence, then dynamic convergence. This sounds like a lot, but as you gain experience it will get easier. When you reach the point that it is as good as it will get and you still have issue with control range then start changing componants. The diodes first and any bad caps. Then start all over. Isn't this fun yet.

Now after saying all this, you said you are still having linerarity problems.
Linerarity, both vertical and horizontal, must be right before you do any dynamic convergence.

To adjust vertical you center the raster first using the vert center control, then use vert height and vert lin to adjust the top and bottom of the picture. I do not remember which control the top and which the bottom, I think the height adjument affects the bottom and the lin adjustment affects the top but it could be the other way around. You will need a crosshatch to do this. When it is correct all the squares will be the same size vertically. You may get the squares all the same size then notice that it doesn't fill the screen at the bottom. This indicates you still have a problem in the vertical output circuit. Usually a bad cap or out of spec resistor. If you do not have enough vertical sweep you will never get good convergence.

Horizontal linerarity is a function of the Horiz output and flyback circuits. Horiz efficency affects the width of the raster as well as the flyback current. The idea is to get sufficent width with the least Horizontal cathode current. If you have an acceptable HO cathode current, but the raster does not fill the screen you need to look for weak tubes, bad caps, and out of spec resistors in the Horizontal drive and output circuits. Try a new Horizontal output tube, since a tired tube may work but not fill the screen.

What you have is looking good. Be patient and good luck.

Bill R

[DaveWM]

Thanks Bill for the encouragement. Taking a deep breath.... ahhhh

fortunitly we have a swap meet to divert me for a bit tomorrow.

What do you think about the Se rectifier on the conv board? I know those can break down over time (Se that is I have no idea about on the conv board).

The blue centering magnet on the top needs to be at the extreme range, it just gets worse as it goes in on the bottom. So that says something is out of whack.

I will give it a break and revisit the purity, guess I as just scared of losing ground.

good news is the pots on the convergence board turn smoothly.

[DaveWM]

oh and got out the wizard of oz disk, that was fun... rubby slippers are fantastic as was the green witch..

[DaveWM]

ok I pulled out the top magnet (blue) and turned it 180 and reinserted, that gave me much better horz blue control on the board. Got the best all white grid pattern yet (and the over the air stuff looks great)


Now I just have to deal with the vert height. if I adj for correct lineairity I come up about 1" short on both the bottom and the top. I if I increase the height adj, then I cant adj the linearity. its like I cant make the circle wide enough to fill out the screen without it becoming a tall oval.

the raster fills out the screen horz, just the image does not get wide enough to match the height, if that make since.

I am using a indian head to do this. Mostly I get a tall skinny circle, again unless I back down the vert, then I can adj lineairity for a nice round circle.

I am going to pickup some new tubes tomorrow vert and horz sweep.

I still have not recapped the filter caps...

[Charlie]

Isn't there a 50@150 electrolytic on the deflection board? Seems I remember changing this particular lytic would always stretch the picture back out to normal.