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  #1  
Old 08-23-2014, 02:46 PM
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Predicta

Well I am unable to fill the bottom. Next?


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  #2  
Old 08-23-2014, 03:13 PM
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Have you replaced the paper and electrolytic capacitors yet in this set? If not, that is the next step. Bad capacitors in the vertical deflection circuitry can cause this.

Other things that could cause this would be a weak vertical output tube, a bad resistor in the vertical circuitry, or a bad potentiometer in the vertical circuitry.

And of course I should check to make sure you know where to find the vertical height and linearity controls on a Predicta -- they are inside the shafts of the vertical hold and brightness controls. Pull the knobs and insert a narrow screwdriver down the hollow shafts of these controls to make adjustments.
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Old 08-23-2014, 03:36 PM
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Yup. Forgot to mention that it is all recapped. And I have adjusted the side controls with flat blade screwdriver. That is as good as it gets. I have not checked any tubes. I had full screen prior to replacing CRT. I will take back off and check vertical output tube and socket.
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  #4  
Old 08-24-2014, 09:41 AM
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Have you rebuilt the couplates? There's two of them that are involved in the vertical: K3 and K4, going by SAMs guide. Otherwise, how does the yoke look? Windings ok?

Good luck with this, your Holiday is better than mine at the moment!
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  #5  
Old 08-25-2014, 12:25 PM
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I did a recap a couple years ago. Misplaced my SAMs now I feel somewhat lost. Yoke and windings look great. I am getting closer with a usable set. Thanks for the tips!!
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  #6  
Old 08-25-2014, 12:46 PM
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You can download the Sams for free at the ETF: http://www.earlytelevision.org/tv_sc...ms_pw_n-z.html
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  #7  
Old 08-25-2014, 01:05 PM
DaveWM DaveWM is offline
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based on that schamatic 1st thing I would do is check the boost voltage at C3 the check resistance from there to the vert osc.
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  #8  
Old 08-25-2014, 01:40 PM
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Have you checked the centering yet?
The two round adjusting screws are on the back of the yoke. If it's too far off center you won't be able to adjust the height and linearity properly.
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Old 08-25-2014, 01:47 PM
DaveWM DaveWM is offline
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wow good idea Eric, had not thought of that, esp since he said it happened after changing the CRT.
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  #10  
Old 10-07-2015, 04:45 PM
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Old thread here, got delayed by life, will work on tips stated above, thank you all so much!!
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  #11  
Old 10-07-2015, 04:57 PM
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My finger pointing to one of back of yoke adjusters you mentioned Eric?
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  #12  
Old 10-07-2015, 06:16 PM
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Quote:
Originally Posted by Dan Starnes View Post
My finger pointing to one of back of yoke adjusters you mentioned Eric?
Yes.
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  #13  
Old 10-09-2015, 05:18 PM
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No luck with those adjustments. I am going to pull the chassis.
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  #14  
Old 10-10-2015, 10:47 AM
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Aha!! Old CRT 2.3 volt. New one is 6 volt. So what do I need to do now?
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  #15  
Old 10-10-2015, 12:44 PM
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Probably nothing. It's a series strung filament designed around 117 volts and you likely have 120+ at your outlets.

Back in the day they would short out a section of the big filament dropping resistor. If you have a shorted section, I'd remove the short if possible.

Regardless, the CRT filament isn;t going to cause the problem you have.

Looks to me like the yoke isn't pushed up tight against the CRT or there's an issue with the vertical output circuit.
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