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  #46  
Old 06-29-2011, 10:00 PM
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bgadow bgadow is offline
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I had a set that would always start out with perfect focus, but over the course of about 10 minutes everything would turn into an unfocused blob. I wasted a lot of time in the focus circuit before subbing the H.O.Tube, which fixed it. That was on a Zenith.
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  #47  
Old 06-30-2011, 06:51 AM
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now pull the crt plug off and hv goes up to 22kv, now i have to find out why, this is making me crazy.
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  #48  
Old 06-30-2011, 08:28 AM
dieseljeep dieseljeep is offline
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It sounds like the CRT is being over-driven. I also noticed all the references to this model, such as tube compliment, etc refer to a CTC12. not a CTC15. There's a considerable difference. Look around the blanker and color difference amp circuits as well.
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  #49  
Old 06-30-2011, 09:48 AM
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i checked source voltages on the bench with no hot in and all seem good higher with no load but the 160v source starts out around 200v and drops down to 123v and stays, but should be much higher with no load.
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  #50  
Old 06-30-2011, 01:09 PM
ctc17 ctc17 is offline
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Quote:
Originally Posted by dieseljeep View Post
It sounds like the CRT is being over-driven. I also noticed all the references to this model, such as tube compliment, etc refer to a CTC12. not a CTC15. There's a considerable difference. Look around the blanker and color difference amp circuits as well.
Good point, 15 uses the JE6. I totally spaced that and Im looking at the schematics. Duh....

Take a break from it and come back next week, these things will make you stupid.
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  #51  
Old 06-30-2011, 08:27 PM
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well i was told by someone that repaired these sets in the 60s and he tells me that the crt has shorts on the cathode, the wire that goes to the focus coil and this coil is getting very hot and starts to smell then i have to shut down. so i checked for shorts in the crt and all 3 guns just keep sparking and they say once you get the sparks to stop then all should be ok but to heat up the focus coil like this can this happen? or is there somewhere else i can go to find out why this coil is this hot and why it cannot focus, crt only?????
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  #52  
Old 06-30-2011, 10:16 PM
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Just reduce the Q of the flyback by inserting a series of pre 1982 solid copper pennies.
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  #53  
Old 07-01-2011, 05:39 AM
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Q ? Copper pennies ?
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  #54  
Old 07-01-2011, 10:54 AM
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well i guess i can call this an update it seems that the hv came up some after blasting the so called shorts in the crt and the sparks are just about gone and the focus coil was heating up because it was run in to far but that was a good position for focus in the beginning. so another 6dq5, and focus adjustment run out more,set up the color guns, agc, and now i have 18-22kv on the crt much better picture but the hv regulation still does not work because on scene changes the hv jumps from 18-22kv its not stable and cannot figure out why unless its the crt but i doubt it. tried 3-3a3, 3-6bk4, 2 6dw4, checked the adjust pot ohms as well as the 2- 1.5 meg resistors which were just above slightly but should be ok. there is only 4 wires green yellow and the heater and everything looks ok but i must be missing something again here.
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  #55  
Old 07-01-2011, 11:23 AM
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Were you using the rejuvenate/restore function on the crt tester to do this? If so, the reason the high voltage is higher now is because you seriously degraded your crt. You basically destroyed your crt by over rejuvenating it and there is less load on the high voltage because the crt emissions are much lower.

The 6DQ5 will cause your problem.

Last edited by ctc17; 07-01-2011 at 11:29 AM.
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  #56  
Old 07-01-2011, 11:53 AM
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emissions are still high and i did not use the rejuvenating or restore function only the remove shorts function, it has improved alot. but the hv is still not regulating.
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  #57  
Old 07-01-2011, 12:34 PM
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Ok,
pull the cap off the 6BK4, hang it out of the way so it cant arc to anything. What does the HV measure with the cap off?

Let me explain it this way.... lets say your car has a regulator on it that will not let it go over 55mph....
Lets say there is something wrong with the engine and it doesnt have enough power to make the car go 45 mph, the regulator never kicks in because the car never reaches 55mph.
Now lets say the car will get up to 55mph on the flat (dim picture) and the regulator holds it at 55. No comes a steep hill (bright picture) and the motor does not have enough power to push the car faster than 35mph up the hill, the regulator never kicks in.

The high voltage system needs to have enough capacity to maintain the high voltage through all operating conditions. If it doesnt the regulator never comes into use. If something is overloading the high voltage like a gassy crt or you have the screens up to high.

Why dont you watch my video on a ctc16 i just restored, i go though a hv problem similar to yours, http://www.youtube.com/watch?v=1AWG61TAIHg
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  #58  
Old 07-01-2011, 03:28 PM
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hello again well i messed up and i cant get into it because its involved but i got the hv working by the pot now but only getting 14kv with the pot all the way up, the 2 1.5 meg resistors are 1.615 and the other is 1.600 do these resistors have to be exact 1.5meg or under.arethese values to high and this is why not getting higher kv? is it normal forthe 6bk4 to show alittle blue when the pot is turned down?
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  #59  
Old 07-01-2011, 04:11 PM
ctc17 ctc17 is offline
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Im kinda intrigued by the fact that you are asking for help yet you refuse to do any of the diagnostic tests suggested.
If you keep throwing parts at it your going to end up with a ruin of a set.
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  #60  
Old 07-01-2011, 04:30 PM
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well i mad a dumb mistake from the start but i now corrected it and i cant type that well to explain but what i did made the hv pot not work at all and im glad i picked up on it because anything i was to test would have come back abnormal and i would have been all over this chassis looking for reasons that could have fixed them self had it not been for the stupid thing i did in the first place. im sorry for all the confusion i have caused everyone here.
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