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#16
07-01-2020, 10:47 PM
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If L8 is shorted and video is getting through, should still work.
I would agree that the first thing is to check the horizontal oscillator frequency. P.S. Wow - talk about corner cutting - only 2 video IF's and both sound and sync taken off the video output AFTER the contrast control. Yet, they spent money on a noise canceller stage. Must have had an extra tube section they didn't know what to do with. 
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#17
07-01-2020, 11:08 PM
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Agree with old_tv_nut on all points. After you get the horiz on frequency, let's see what the actual video looks like.
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#18
07-02-2020, 11:23 AM
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I’ve tried adjusting the Horiz freq numerous times, following the Sams guide, by centering the Horiz lock and then moving the Horiz freq. Just can never get sync, and always overlapping pictures or “xmas tree” effect.
Wondering if I should put the output of the Hor freq coil on the freq counter. The only thing I can think of is either the coil is bad or there still remains a faulty component or lead that needs to be traced down. Either that or the Horiz osc tube needs replacing. This tube, tested fine for emissions and Gm on both a Hickok 533 and Mercury tester. I have one 5u8 on order anyway, just to make sure it’s not a defect the testers didn’t detect. Last edited by Jon1967us; 07-02-2020 at 11:27 AM.
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#19
07-02-2020, 11:42 AM
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Yes, use a frequency counter, or just use your scope first to see if the frequency is even close.
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#20
07-02-2020, 02:23 PM
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So...progress...in fact, a big step!
Using my trusty counter I did find the Hor freq coil was set very low. The coil after it, which acts as a kind of range setter was way off as well. Having dialed these two coils into range, 15.500-750 ish and the H lock into a mid position, i was able to get rid of this pesky Horiz sync problem and my multiple pictures have gone away. Big learning moment! Give the dang frequency counter some love! Now I can see the line, crosshatch and staircase patterns. Vertical lock remains a problem, especially as the control no longer affects anything. Vert linearity and height work though. Please enjoy these progress pics: https://ibb.co/fY1pqX4 https://ibb.co/5W7QDPd https://ibb.co/rp1WJfg Adding a short video https://youtu.be/9mdcOzbqWaw Last edited by Jon1967us; 07-02-2020 at 02:42 PM.
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#21
07-04-2020, 02:04 PM
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Discovered that pins 3,4 were shorted somehow to each other on the Vert osc / output tube. Fixed that and much of the noise and some instability went away.
Still have the issue of a split vertical picture. Still syncing issues to be addressed. https://ibb.co/rpWHvYR
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Linear Mode
