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  #46  
Old 02-11-2019, 06:25 AM
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You will see in the schematic the values of the Micas, IIRC there a couple of 100mmf and I think one 250mmf but check the schematic. What did you use for the hv defection caps.

Last edited by timmy; 02-11-2019 at 06:28 AM.
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  #47  
Old 02-16-2019, 11:05 PM
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Quote:
Originally Posted by timmy View Post
You will see in the schematic the values of the Micas, IIRC there a couple of 100mmf and I think one 250mmf but check the schematic. What did you use for the hv defection caps.
I used .0047 and .001 film caps at 6kv (From JustRadios)



Well, got the new caps and replaced most of the components in both the vertical and horizontal sections. There's still a significant jitter, and the picture quality appears to be getting worse the longer I troubleshoot. Any ideas?
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Last edited by Zsuttle; 02-16-2019 at 11:08 PM.
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  #48  
Old 02-17-2019, 02:32 AM
EdKozk2 EdKozk2 is offline
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Hi,
What kind of jitter are you seeing, vertical or horizontal? Many of the tv's and radio equipment I repair have flaky potentiometers. They can be a source of erratic operation. A little electrical contact spray helps sometimes.
Ed
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  #49  
Old 02-17-2019, 09:48 AM
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I've had Tin whisker issues in pots in TS-4 Motos before. Also the Mica caps in the sweep can be problematic.
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  #50  
Old 02-17-2019, 10:26 AM
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I changed the value of the resistor on the wiper of the vertical lock form 3.3m to 4.7m and was able to get a lock on the vertical. However, by replacing other components, the image now looks like this and this.
20190217_111017_004_01.jpg
20190217_111017_005_01.jpg

I think it's something in the video sections affecting the sync signal before it gets stripped?

I've replaced most of the components in the vertical and horizontal sections, though that's made the video worse than what it was before.
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  #51  
Old 02-17-2019, 02:01 PM
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There is also a mica under the 12sn7, horizontal sweep, don't know if you changed that one but if you didn't be careful when changing make sure it's the right value and don't make a mistake putting the legs back in the correct position otherwise the horiz won't run and it will burn up the horiz hold pot. At one point I had changed the resistor to get vert to lock only to realize that I missed a mica in the verticle section and once changed I put back the right resistor and it was fine. Look in the schematic at the vert and horiz section and write down all the caps that are marked MMF those are the ones to change. The one under the horiz tube looks like a dogbone. Although some look like dog bones and others look like a domino.

Last edited by timmy; 02-17-2019 at 04:48 PM.
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  #52  
Old 02-17-2019, 04:46 PM
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Just for the heck of it run the set and turn the horiz hold pot all the way to one end then start back to get the best pic because you can get a pic but will have distortion if turned to much in the opposite position, it's happened to me .
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  #53  
Old 02-17-2019, 05:59 PM
TonyP TonyP is offline
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Ive recapped my VT71 and it has a case of slight horizontal and vertical jitters. then again, every tv where i use the dvd plaver has the same jitter issue. i wish i had ann over the air signal to use. maybe it the video source causing the jitters
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  #54  
Old 02-17-2019, 06:29 PM
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Ive recapped my VT71 and it has a case of slight horizontal and vertical jitters. then again, every tv where i use the dvd plaver has the same jitter issue. i wish i had ann over the air signal to use. maybe it the video source causing the jitters
did you try one of those 75-300 ohm transformers where it has the threads on one end and the 2 wires on the other, that's what I use and it's perfect.
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  #55  
Old 02-19-2019, 02:52 PM
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Well, I had replaced all of the caps in the sweep circuits. Later today I'll try injecting a composite signal and seeing where that gets me.

~Zach
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  #56  
Old 02-19-2019, 03:43 PM
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Well, I had replaced all of the caps in the sweep circuits. Later today I'll try injecting a composite signal and seeing where that gets me.

~Zach
It may be possible that the alignment is out just a little, if you check the schematic you can very slightly move the channel 3 adjustment on top of the chassis, but do make sure you have a good signal to start with.
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  #57  
Old 02-19-2019, 07:04 PM
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Well, tried injecting a signal, couldn't get it to go through the way I wanted. I've combed over the horizontal, vertical, and sync and cannot seem to locate the problem. Is it possible that it's emanating from earlier in the circuit in one of the video sections? The picture appears darkened and has the horizontal jitter. The frame is not centered all of the way, with a little black bar at the bottom.
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  #58  
Old 02-20-2019, 05:27 AM
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More pics.. You said the pic is on the dark side and Alittle jittery, have you checked the contrast/ agc adjustment on the front right. There may be 2 caps off that pot, maybe check them.

Last edited by timmy; 02-20-2019 at 06:25 AM.
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  #59  
Old 02-20-2019, 08:49 AM
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May want to scope the sync separator...if it is letting video or noise through that could be freaking out the sweep.
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  #60  
Old 02-20-2019, 02:42 PM
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Quote:
Originally Posted by timmy View Post
More pics.. You said the pic is on the dark side and Alittle jittery, have you checked the contrast/ agc adjustment on the front right. There may be 2 caps off that pot, maybe check them.
It could be, the when the contrast is all of the way up, the picture goes out of control. I'll replace the three that are there. EDIT: I was able to successfully get the picture back to normal by replacing the three capacitors around the contrast control. However, the slight shudder is still there along with the uncontrollableness created by turning the contrast or brightness to full.

Quote:
Originally Posted by Electronic M View Post
May want to scope the sync separator...if it is letting video or noise through that could be freaking out the sweep.
Not entirely sure what to look for, however, here's the output of the plate on the sync. Hopefully that helps.

20190220_153323[1].jpg


I've also purchased a TV analyst for troubleshooting, seems like a useful tool. WOn't be here for another week
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Last edited by Zsuttle; 02-20-2019 at 03:03 PM. Reason: Partial fix on issue.
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