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#1
10-29-2009, 05:16 PM
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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 
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#2
10-29-2009, 10:24 AM
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If I'm not mistaken, modern sets go thru the menus to get to convergence. Seems that big screen sets have a menu that the user can get to and perform convergence, and from what I've seen, it's quite easy and just about anyone can do it as long as they have decent vision. I made some convergence adjustments on my neighbor's big screen a few years ago... it was rather easy. Certainly came out better than a roundie!
 I believe smaller sets have a secret menu that is not available to the set's owner. If you bring the set in for repair, the repair man knows a certain sequence of buttons to push to bring up the service menu... and I would think convergence would be in there. We've had discussions here before about the secret service menu... they were pretty interesting.
__________________
Charlie Trahan He who dies with the most toys still dies.
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#5
10-29-2009, 08:52 PM
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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... Last edited by DaveWM; 03-18-2013 at 12:04 PM.
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#6
10-29-2009, 09:01 PM
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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.
__________________
Charlie Trahan He who dies with the most toys still dies.
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#8
10-29-2009, 10:21 PM
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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.
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#9
10-30-2009, 12:11 PM
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Quote:
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
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#10
10-30-2009, 07:25 PM
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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. Last edited by DaveWM; 10-30-2009 at 07:32 PM.
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#12
10-30-2009, 10:10 PM
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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.
__________________
Charlie Trahan He who dies with the most toys still dies.
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#13
10-30-2009, 10:20 PM
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that was the only one I did (since the vert output tranny was smoked I did repalce that one, it was leaky, IIRC the resistance measurement was correct as well), that was the cathode bypass cap I think, it was on the board. I have not touched any of the big can caps yet.
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#14
11-01-2009, 08:37 PM
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pic of the hot fuse location. quick easy to check the HOT current just pull the fuse and take a reading, sorry for the blur.
No holes drilled easy to undo if for some reason a future restorer does not like it. Last edited by DaveWM; 03-18-2013 at 12:04 PM.
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#15
10-31-2009, 12:46 AM
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I would adjust for correct linearity and look for the problem in the vertical sweep circuit. Probably a bad cap. Check B+ in the vert circuit as well. You just do not have enough vertical sweep. This will also effect convergence.
With their age the Selenium rectifiers on the convergance board should probably be replaced. I don't recall changing many in the day, but they are much older now. I think those are more reliable than ones used in the power supply. I would change them. If for no other reason to make the set more reliable. Bill R
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