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  #61  
Old 04-01-2015, 09:05 AM
DaveWM DaveWM is offline
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Quote:
Originally Posted by andy View Post
That works if you're out of range at the high end of the focus pot. I added a series resistor to the high side of the focus pots in both of my GE 10JA sets to get the focus centered. Interestingly, they were both off by the same amount, and haven't shown any drift yet.

If you're at the low end, you have no choice but to replace the focus divider since you can't add a negative resistor.
that was the prob on mine, could not go low enough, even shorting the 4.7 meg would not get me there.
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  #62  
Old 04-01-2015, 12:21 PM
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I have a plastic cabinet tabletop 19DC12 and my focus pot is in the "vert centering" apron hole as well. I thought it was an upgrade mod.

I also had a 19DC11 set that was otherwise identical and had the divider resistor like Tom's earlier set. The focus control was mounted on a fiberglass board at the fly and the control had a long shaft that stuck out the back.

As I recall, the focus was better on the 19DC11 but I gave it to Bryan Gadow in one our frequent set-swaps.
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  #63  
Old 04-01-2015, 05:52 PM
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Quote:
Originally Posted by DavGoodlin View Post
I have a plastic cabinet tabletop 19DC12 and my focus pot is in the "vert centering" apron hole as well. I thought it was an upgrade mod.

I also had a 19DC11 set that was otherwise identical and had the divider resistor like Tom's earlier set. The focus control was mounted on a fiberglass board at the fly and the control had a long shaft that stuck out the back.

As I recall, the focus was better on the 19DC11 but I gave it to Bryan Gadow in one our frequent set-swaps.
IIRC the ones with the glass board all had a big disc cap that would arc.
The caps were pulled & a tripler kit subbed. The original tripler was
a weird looking thing like a ladder & was red. Not too many
came that way. There were a lot of varieties in the hybrids HV.
I only did one FBT on one & it was a big kit & included a tripler
IIRC.

73 Zeno
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  #64  
Old 04-05-2015, 08:40 PM
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Dreamsbeard Dreamsbeard is offline
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Ok, now I located the 9-27 board. Before I went to adjust the APC control, I went and change the DVD in my player to put back my terminator DVD that has the THX pattern...and that was the last time my TV was able to lock in on the signal that was feed via the RF modulator. Now not only the color won't lock in , but the whole picture won't (see picture).

That occured while the TV was on, and I didn't even touch the TV between the dvd swap...it was ok...then it went bongo.

I tried a different RF modulator, tried to lock the signal by turning the VHF tuner...nada.

At least I have great colors now :P
Attached Images
File Type: jpg 19DC12-12.jpg (61.1 KB, 21 views)
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  #65  
Old 04-05-2015, 09:15 PM
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Looks like a complete loss of horizontal sync. Perhaps that tube you subbed in was not suitable.
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  #66  
Old 04-06-2015, 05:24 AM
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Quote:
Originally Posted by Jon A. View Post
Looks like a complete loss of horizontal sync. Perhaps that tube you subbed in was not suitable.
Possible, but I replaced every tube with same number ones and it worked fine for a couple hours... I will try to sub some of the old ones to see.
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  #67  
Old 04-06-2015, 08:00 AM
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Its the hoz hold on rear, white knob. If its at the end
you can pull back the the sleeve to move it more.
Change channels back & forth when setting so it
syncs right in. Its a coil so it can turn many times.
The lines will get father apart as you go in the right
direction.
Only tube that can do it is the 6U10.
If the horz is near falling out of sync it can cause
color sync probs also.

73 Zeno
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  #68  
Old 04-06-2015, 09:38 AM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by zeno View Post
IIRC the ones with the glass board all had a big disc cap that would arc.
The caps were pulled & a tripler kit subbed. The original tripler was
a weird looking thing like a ladder & was red. Not too many
came that way. There were a lot of varieties in the hybrids HV.
I only did one FBT on one & it was a big kit & included a tripler
IIRC.

73 Zeno
I've seen that trippler and I understand that it was a Selenium stack and German made. I omly saw one Zenith that used it.
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  #69  
Old 04-07-2015, 01:50 AM
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Quote:
Originally Posted by Dreamsbeard View Post
Possible, but I replaced every tube with same number ones and it worked fine for a couple hours... I will try to sub some of the old ones to see.
Oh, I thought you subbed a different tube due to high cost.
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  #70  
Old 04-07-2015, 05:04 PM
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So, finally it only was the horizontal Hold that made the fuzzy picture, everything works now. I redid convergence, and now it got a good picture! I am still not 100% blown away by it as much as I thought I would be, but its definitly is a drastic improvement from where I began.

Now, there are the small issues of : Jail bar, and of course getting rid of that pesky macrovision buzz and color lines! Anyone knows a good macrovision filter? I bet this could get handy with pretty much all the sets made before 1980 or something...?

Quote:
Originally Posted by Jon A. View Post
Oh, I thought you subbed a different tube due to high cost.
I did, but the subs where also marked as alternative right in the back cover of the TV. By the way, what would be the effect of replacing an 6LX6 by a 6LF6 other than it would have cost me twice as much haha?

Last edited by Dreamsbeard; 04-07-2015 at 09:47 PM.
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  #71  
Old 04-08-2015, 07:04 AM
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zeno zeno is offline
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Quote:
Originally Posted by Dreamsbeard View Post
I did, but the subs where also marked as alternative right in the back cover of the TV. By the way, what would be the effect of replacing an 6LX6 by a 6LF6 other than it would have cost me twice as much haha?
The sub makes no difference. IIRC all Zenith came with a
6LX6 or 26LX6 on series sets. Only other sets I recall were
Motorola hybrids came 6LF6 or 20LF6. Others probably used it.
I dont remember on Motorola but Zenith can sub 20LF6 for
26LX6.

Price difference probably due to most hoz outputs are used by
hams for amplifiers One tube probably has specs that are better
so more demand.

73 Zeno
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  #72  
Old 04-18-2015, 09:32 AM
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Good morning everyone,

So in the light of the thread about my newly aquired flatchassis, I decided to go back to my hybrid and redo convergence with colors off to see if I could improove things a bit. What bothers me with my hybrid is the same thing that bothers me with my flatchassis : Both got great colors, but I think that the picture is washed out, and color is blooming even if convergence is accetable. So this time I did a side by side comparaison shot with my daily watcher (1986 Hitachi console).

Here's are the results. Picture 1/2 crosshatch pattern colors off/on on my hybrid, picture 3 and 4 are comparaison shot hybrid/Hitachi. You will notice how much sharper the text is on the Hitachi. I did ajust the focus on the hybrid more than once to make sure it was spot on.

At this point, I wonder if it has anything to do with bad convergence at all...could it be chroma bandpass as Electronic M said in the flatchassis thread?
Attached Images
File Type: jpg hybrid-1.jpg (81.2 KB, 14 views)
File Type: jpg hybrid-2.jpg (67.4 KB, 16 views)
File Type: jpg hybrid-3.jpg (122.9 KB, 18 views)
File Type: jpg hitachi-comp.jpg (111.1 KB, 20 views)

Last edited by Dreamsbeard; 04-18-2015 at 09:38 AM.
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  #73  
Old 04-18-2015, 12:44 PM
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Electronic M Electronic M is offline
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That blush of color in the lower multi-burst pattern shows the color circuits reacting to what should be a monochrome signal. It would be interesting to know the frequency at which this is occurring. It could be alignment issues or it could be a design limitation of the set lacking a comb/notch filter.
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  #74  
Old 04-18-2015, 10:50 PM
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Quote:
Originally Posted by Electronic M View Post
That blush of color in the lower multi-burst pattern shows the color circuits reacting to what should be a monochrome signal. It would be interesting to know the frequency at which this is occurring. It could be alignment issues or it could be a design limitation of the set lacking a comb/notch filter.
A notch filter is only applied to luma, never to chroma (it would eliminate the color signal from the color circuits!). So, you are seeing the expected effect with a notch filter set, with luma in the color bandpass showing as flickering color.The short shutter time used for the picture captures one phase of the cross color instead of averaging it out, making it look worse.

In both shots (color on and color off), the black level (don't know if it's labeled "brightness" on this set) is set too low. This makes the darker gray scale chips all look black, and may have prompted the chroma to be turned up too high to bring up the red and blue bars, also increasing the visibility of the cross color.
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  #75  
Old 04-19-2015, 09:46 AM
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Quote:
Originally Posted by old_tv_nut View Post
A notch filter is only applied to luma, never to chroma (it would eliminate the color signal from the color circuits!). So, you are seeing the expected effect with a notch filter set, with luma in the color bandpass showing as flickering color.The short shutter time used for the picture captures one phase of the cross color instead of averaging it out, making it look worse.

In both shots (color on and color off), the black level (don't know if it's labeled "brightness" on this set) is set too low. This makes the darker gray scale chips all look black, and may have prompted the chroma to be turned up too high to bring up the red and blue bars, also increasing the visibility of the cross color.
I tried, various setup of brightness/contrast , and it is true that higher contrast (lower brightness) seems to help a bit, but the worst offender here is the "color" ajusting. I can get the color where it's not blooming that much anymore...but the picture gets very dull (not much colors).

Could it be that, a mix of cheap RF modulation and macrovision fed to a television that wasn't desing to receive and process that kind of signal could "degrade" the picture like that? How do you guys with roundy go about to get the very best image on your sets?

Oh and BTW, I am still not getting any snow when the TV receive no signal, only a white uniform picture. Could it give a clue to what's wrong?

Thanks!
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