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s-video mod 9 vertical lines on left side


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#26 FABombjoy OFFLINE  

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Posted Thu Nov 21, 2013 7:31 PM

Oh, ha... now that I'm not on Tapatalk I can see the Moon Patrol screenshot icon_biggrin.gif

 

I wouldn't think you have to replace any, just supplement in parallel.  If you look at the 16-bit era, 10uF (Sega / Pioneer) through 22uF (NEC) were typical values for bypass caps.  Again I'm just kind of "writing out loud" here and haven't tested any of this, except for adding caps to the RAMs themselves.  There could be other loop issues present due to the twin 7805s design.  According to the schematic, the RAMs and ANTIC/GTIA aren't even fed by the same regulator.



#27 grips03 OFFLINE  

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Posted Thu Nov 21, 2013 8:33 PM

I did some testing tonight:

 

Same results with Moon Patrol on Atarimax and genuine cart.

 

If cap C1 is removed the 9 lines on left of screen are very bold

 

So I tried various caps at C1 = 10uf, 1uf, .1uf, .1uf and .01uf. All give the same results.

 

Also pause does make the 9 lines less, but they are still there, but just barely.



#28 SoundGammon ONLINE  

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Posted Sun Jan 10, 2016 2:22 PM

Anyone try shielded wire on all the video lines?

 

Keep any outside signals from getting into and amplified into the signal?

 

I remember the old RF days when a bad shield would induce all kinds of video noise.

 

Microphone cables should work well.



#29 grips03 OFFLINE  

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Posted Sun Jan 10, 2016 3:33 PM

i did that too, did not fix the issue



#30 -^CrožBow^- ONLINE  

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Posted Sat Feb 6, 2016 9:09 AM

What is odd is that his moon patrol screenshot looks similar to the banding that occurs on the same left hand side from the 130xe? So could it be the GTIA itself that is causing this? I've done the s-vid mod on 4 different 5200's and have never seen this before other than from the RF on my 130xe.



#31 -^CrožBow^- ONLINE  

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Posted Thu May 18, 2017 1:34 PM

i did that too, did not fix the issue

Did you ever resolve this? Again, I've done several 5200 mods using Joe's board on all of them and they looked great! Then again, it could be a TV thing. I did the simple composite mod on a 7800 for someone and it looked good on my CRT I was using to test it with, but then the guy that I did the mod for hated it because apparently on his Sony WEGA CRT it had bad jailbars in the video? I didn't see them on the JVC i used to test it but he did. So..again, different TVs produce different results. 



#32 grips03 OFFLINE  

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Posted Thu May 18, 2017 7:29 PM

No resolution with Joe's mod.  Bryan's new board might fix the issue, but not sure if they are out yet. 



#33 -^CrožBow^- ONLINE  

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Posted Fri May 19, 2017 7:10 AM

No resolution with Joe's mod.  Bryan's new board might fix the issue, but not sure if they are out yet. 

 

Bryan is making up a batch of UAVs now.. I have 2 on order in fact. Will be putting one of them into my 7800 to see if I can finally get some decent upgraded video quality from it. But yeah, strange with your 5200 mod. Again, I've done several of these all with Joe's board and honestly, the 5200s on s-video look better than any of my other classic consoles upgraded. Been nothing but totally pleased with the results.

 

Send Bryan a PM about getting a UAV and hopefully that will get your 5200 cleaned up as well.



#34 R.Cade OFFLINE  

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Posted Fri May 19, 2017 7:33 AM

"Jailbars" occur on any old system, and largely depends on the display, power and other factors, but mostly the design of the board- i.e. routing of video signals, and filtering.

 

Bypass caps strategically spec'd and placed can reduce them but usually not remove them completely. It's different for every system.


Edited by R.Cade, Fri May 19, 2017 7:34 AM.


#35 DrVenkman OFFLINE  

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Posted Fri May 19, 2017 3:48 PM

I see similar lines on my modded 800XL (using Bryan's Rev C and current Rev D UAV boards). They are nearly imperceptible except during SIO and RAM access. The lines are much better using the Rev D compared to the earlier Rev C board. For what it's worth, I see these lines no matter whether the UAV is powered and grounded by the 4050 socket directly, or if separate ground and power are provided (+5V coming from near the power jack and grounded to the DIN or the RF shielding plane. 

 

There's quite a lot of discussion of these visual effects on the two UAV threads and they just seem to be pretty much the result of very "noisy" board designs and perhaps the aging of those tiny filter caps all over the board.






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