#61
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There is no change in resistance on pin 2 of v13 when the horizontal size pot is turned . but the voltage tests do vary with the movement of the size and hold pots.
Last edited by timmy; 03-22-2017 at 02:52 PM. |
#62
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Are you measuring the resistance from pin 4 of M-5, like the note at the bottom of the table says?
jr |
#63
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Sure did
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#64
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C-75 could be shorted, but I doubt that the horizontal would work ok if it was... a real head-scratcher.
jr |
#65
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That's a 900mmf that cap along with the other Micas were changed but each one I replaced I tried the set and after all of them were replaced I was left with the same problem. I checked the horiz afc and block trans and ohms are perfect. So I don't know what it is with pin 2 or if it even has to do with this odd problem.
Last edited by timmy; 03-22-2017 at 04:14 PM. |
Audiokarma |
#66
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Could the blocking trans have a primary to secondary or windings to frame short?
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#67
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These transformers are small round things dipped in wax and the one trans is on a tie strap and the other is in a can on top and I took that apart and that one has insulating paper wrapped around it. So I guess it's safe to say I don't think there is a winding short to ground unless the ground was leaking in from somewhere else , I don't even know where to start to look for a possible ground leak into the verticle, and There is no 60hz hum in the audio.
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#68
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Still didn't figure this out, but there is 2 10meg resistors at the 6sl7 that I checked and also tried others and didn't work was the same no different but the one 10meg that is across pin 4 and 6 if I put a 1 meg across the 10meg I get a picture and vert hold the linearity is off on top and the hold is Alittle touchy. pin 6 is wired for ground and the one end of the .004 is also tacked to ground. It seems as if the tube is not conducting by why with a 1 meg it calls for 10 meg. If I try a 1 meg across the other 10meg it works very little bad picture and no response from vert hold or size. All this changes with the one resistor at 4 and 6 . I can't measure the voltage on the plates of the 6sl7 with a Dvom I won't get an accurate reading but measuring I do get a reading of 120 Vdc and 75 Vdc the SAMs shows a lot more so my meter won't tell but changing that resistor to a 1 meg I'm thinking lowering that resistor seems to allow the tube to conduct with possibly low voltage on the plates but the screen is super bright. The plates get voltage from the hv with the resistors which check ok. This is nuts already, I'm open to anything at this point
Last edited by timmy; 03-23-2017 at 11:23 AM. Reason: Added more info |
#69
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Have you tried a different 6SL7? Possibly this one has grid emission.
Could there be a carbon path in the tube socket between pins 5 and 4 that is pulling the grid more positive than it should be? You really need to get better voltage measurements... can you get another HV probe or fix the one you have? jr |
#70
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Quote:
Last edited by timmy; 03-23-2017 at 01:26 PM. |
Audiokarma |
#71
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I would unsolder all of the connections to either pin 4 or pin 5 and mesure resistance between the two pins... leakage as high as 10 meg or so could mess up the bias on the tube.
You really need to get another HV probe, as low HV could be te main source of the problem. jr |
#72
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Quote:
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#73
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The tube shouldn't make any difference, unless it is the cause of leakage... try it both ways. You could also check the tube itself for any leakage between pins, but since you have tried several different tubes without changing the symptoms, it is unlikely that you will find any leakage unless they all have the same fault.
jr |
#74
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Timmy,
Did you ever try spraying any cleaner into the vertical hold and size control to see if it would stabilize the vertical roll? Did you try wiggling V9, V11, or V12 while the set is on to see if it helped? I come across worn and dirty contacts all the time in old equipment. The cause of all sorts of issues. Just because parts are swapped or tested doesn't always eliminate the root cause. Do you understand how the vertical feedback loop works with this set? If you have a scope, check to see if you are getting the proper trigger signal to your vertical oscillator grid from the sync separator/ integrator network. Ed |
#75
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Quote:
Last edited by timmy; 03-23-2017 at 07:58 PM. |
Audiokarma |
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