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  #16  
Old 03-30-2012, 04:44 PM
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Keep yr chin up, Timmy, you'll get it !
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  #17  
Old 03-30-2012, 05:18 PM
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pulling those tubes did nothing so back to the drawing board. and i really dont want to touch the micas as they say these sets usually dont need them and replacements cause more problems.
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  #18  
Old 03-30-2012, 08:29 PM
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Try pulling the first two (not the osc tube) out and see if your cathode current goes up to 150 milliamps of so. Without the schemo, I'm not sure. Ill see if I have it.
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  #19  
Old 03-31-2012, 12:03 AM
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Quote:
Originally Posted by Electronic M View Post

The horizontal AFC is meant to compare the oscillator frequency to the synch, and pull the horizontal oscillator frequency to match the synch. If the horizontal AFC circuit is bad it can pull the horizontal oscillator waaaay off normal operating frequency. The horizontal AFC circuit comprises all tubes on the schematic that are between the synch tube and horizontal oscillator tube. Pulling the tubes in the AFC will disable it and make trouble shooting oscillator issues easier.
Its a primitive type of phase lock loop.
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  #20  
Old 03-31-2012, 12:06 AM
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Quote:
Originally Posted by timmy View Post
pulling those tubes did nothing so back to the drawing board. and i really dont want to touch the micas as they say these sets usually dont need them and replacements cause more problems.
ANY MICAS IN THE HORIZONTAL SECTION MUST BE CHANGED!!!! AND YES I AM YELLING THAT.

They are ALWAYS bad, the only ones that dont need to be change are the ones in the IF that dont have much dc voltage across them.
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  #21  
Old 03-31-2012, 08:54 AM
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well just now im hearing that the micas are infact not bullet proof and i guess they should be changed. are there any substitute caps to use in place of the values of the micas like mylar caps?
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  #22  
Old 03-31-2012, 07:34 PM
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Even though it wont be popular, I use disc caps to replace micas. Keep them away from any heat source and they work great.

If you look at newer sets they all use discs where the old ones use micas.
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  #23  
Old 04-06-2012, 08:21 AM
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well changed the micas in the horiz circuit and still no drive on the hot. i have been working with don lindsly and we checked voltages and it seems that there is a frequency but its to low to drive the hot. and now we cannot do anything else unless i have a scope which i dont have so im in the dark now with this set. i checked all the resistors in and around the horiz circuit and and found nothing out of tolarance. dont know where to go from here. tried other tubes and nothing. simple b&w is turning into a nightmare.
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  #24  
Old 04-06-2012, 09:47 AM
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What is the screen voltage on the hot and what is it spost to be?
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  #25  
Old 04-06-2012, 10:03 AM
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well i got the chassis out now but the voltages were close to what they spost.. to be but the neg voltages were high. i dont remember what they were as i was on the phone with don doing this. he thinks the problem is around the horiz discharge tube but cant find anything wrong. the only thing i have left to try is i had to sub the horiz reactance tube 6ac7 for a 6ab7 which is said to be a match for a sub but maybe i should get the right tube rather then the 6ab7 maybe they are different.
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  #26  
Old 04-06-2012, 12:43 PM
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with the chassis on bench no crt control grid pin 5 of hot is neg 101 vdc and screen grid 205 vdc. pin 5 should be neg 94 vdc pin 8 should be 165 vdc.
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  #27  
Old 04-06-2012, 03:49 PM
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Originally Posted by timmy View Post
with the chassis on bench no crt control grid pin 5 of hot is neg 101 vdc and screen grid 205 vdc. pin 5 should be neg 94 vdc pin 8 should be 165 vdc.
If the screen should be 165 and is measuring 205..

The tube is weak or there is excessive plate current.
Some kind of overload in the output like shorted fly, bad linearity coil, bad yoke, bad caps, bad damper, something causing the fly to be overloaded.
I guess if the frequency was way off it could cause that but if it was low you should hear it squeeling
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  #28  
Old 04-06-2012, 04:02 PM
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the fly dont even get warm neither does the yoke and the cathode currant is 110ma. the 6ac7 tube is a sharp cutoff where the 6ab7 i am using is a remote cutoff as i am thinking maybe this could be a problem? and no squealing going on. and i tried 2 other tubes.
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  #29  
Old 04-06-2012, 11:14 PM
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Timmy flavored jelly beans.

Im looking at a schematic for a TV30 cuz thats all I can find, where are you getting a TV125 schematic? What are you looking at?

The TV30 has a very confusing damper/output side of the flyback.
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  #30  
Old 04-07-2012, 05:58 AM
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this fada set is called tv 125 because it dont have channel 1 and its got the rca clone 630 chassis. i have the sams photofact for rca 630 chassis.
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