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Weak video signal on Atari 5200


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#1 dino999 OFFLINE  

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Posted Tue Jun 12, 2018 8:57 PM

My two-port 5200 has a weak video signal. Besides the static, it's so dim that I can't see some images in games like enemy bullets in Space Invaders. Does anyone have any recommendations for troubleshooting? Would composite or s-video mod bypass any problem this RF video is having?

 

I've already swapped A5 (GTIA) and A3 (ANTIC) with known working replacements. They didn't change anything.

 

I took pictures of the board here --> https://imgur.com/a/QOO9QoW

 

Here are thumbnails. Click on them to get a really big picture to open in a new tab.

KBoukk1m.jpg 0MTUBM8m.jpg

dtSX99um.jpg 45MY5LSm.jpg


Edited by dino999, Tue Jun 12, 2018 8:57 PM.


#2 atari-dna OFFLINE  

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Posted Wed Jun 13, 2018 4:40 AM

[quote name="dino999" post="4047693" timestamp="1528858636"]My two-port 5200 has a weak video signal. Besides the static, it's so dim that I can't see some images in games like enemy bullets in Space Invaders. Does anyone have any recommendations for troubleshooting? Would composite or s-video mod bypass any problem this RF video is having?
 
I've already swapped A5 (GTIA) and A3 (ANTIC) with known working replacements. They didn't change anything.

Have you tried tuning the RF modulator to match channel 3’s frequency?

What is your video like on channel 2?


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#3 dino999 OFFLINE  

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Posted Wed Jun 13, 2018 8:46 PM

Have you tried tuning the RF modulator to match channel 3’s frequency?

What is your video like on channel 2?

 

I am using the female phono jack to male coax adapter to connect to my TV. I tested channels 2, 3, and 4, using both circle and square settings of the switch on the back of the system. The video performance did not improve.

 

Here is a screenshot of Space Invaders. Click on it to see the extremely large original image. It's very dim. You can barely see the last row of aliens. Forget seeing their lasers. They're lost in the ether.

IDFqmQam.jpg


Edited by dino999, Wed Jun 13, 2018 8:49 PM.


#4 atari-dna OFFLINE  

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Posted Thu Jun 14, 2018 1:06 PM

 
I am using the female phono jack to male coax adapter to connect to my TV. I tested channels 2, 3, and 4, using both circle and square settings of the switch on the back of the system. The video performance did not improve.
 
Here is a screenshot of Space Invaders. Click on it to see the extremely large original image. It's very dim. You can barely see the last row of aliens. Forget seeing their lasers. They're lost in the ether.
IDFqmQam.jpg


You may want to experiment with adjusting the color delay resistor. I’ve circled this in the photo below.
Can’t hurt to dial through it, maybe it’s out of phase and artificially dark. Otherwise it’s likely transistors/resistors which are failing...

Try tweaking this adjustable potentiometer and report back!

93ff758a27aed12f66efbda10346b450.jpg




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#5 -^CrožBow^- OFFLINE  

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Posted Thu Jun 14, 2018 1:25 PM

 

I am using the female phono jack to male coax adapter to connect to my TV. I tested channels 2, 3, and 4, using both circle and square settings of the switch on the back of the system. The video performance did not improve.

 

Here is a screenshot of Space Invaders. Click on it to see the extremely large original image. It's very dim. You can barely see the last row of aliens. Forget seeing their lasers. They're lost in the ether.

IDFqmQam.jpg

 

Just out of curiosity, what happens if you try and adjust the contrast setting on your TV? Honestly the image while very dark, does look pretty clear otherwise for RF. 



#6 atari-dna OFFLINE  

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Posted Fri Jun 15, 2018 8:07 AM

 
Just out of curiosity, what happens if you try and adjust the contrast setting on your TV? Honestly the image while very dark, does look pretty clear otherwise for RF. 


Good point, the television could be the culprit.


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#7 dino999 OFFLINE  

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Posted Fri Jun 15, 2018 5:32 PM

Just out of curiosity, what happens if you try and adjust the contrast setting on your TV? Honestly the image while very dark, does look pretty clear otherwise for RF.

It seems strange that I didn't adjust the default TV settings for the coax input. Most of the other games I own have a discernible image. My Atari 2600 is even more clear and bright on the same input. Nonetheless, I still feel silly that I didn't try it.
 
I increased the brightness from 50 to 80 and now the image is good. Hnh, I didn't know the bases in Space Invaders have a shifting rainbow pattern. Neat.
 
I still think there is something weak about the output given the 2600 looks great at the default settings.

 

You may want to experiment with adjusting the color delay resistor. I’ve circled this in the photo below.
Can’t hurt to dial through it, maybe it’s out of phase and artificially dark. Otherwise it’s likely transistors/resistors which are failing...

Try tweaking this adjustable potentiometer and report back!


Could this brighten the picture? What does it actually do to the components? Does it cause some component to draw more current?

 

I know I may be stepping ahead, but could replacing the voltage regulators improve the picture? In my search for info to help with the repair, I found this video where the voltage regulators and their heatsink are removed and replaced:

I only ask since I remember reading something about a faulty NES voltage regulator (same type used in the 5200) causing some similar problems.



#8 atari-dna OFFLINE  

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Posted Fri Jun 15, 2018 5:43 PM

It seems strange that I didn't adjust the default TV settings for the coax input. Most of the other games I own have a discernible image. My Atari 2600 is even more clear and bright on the same input. Nonetheless, I still feel silly that I didn't try it.
 
I increased the brightness from 50 to 80 and now the image is good. Hnh, I didn't know the bases in Space Invaders have a shifting rainbow pattern. Neat.
 
I still think there is something weak about the output given the 2600 looks great at the default settings.

 

Could this brighten the picture? What does it actually do to the components? Does it cause some component to draw more current?
 
I know I may be stepping ahead, but could replacing the voltage regulators improve the picture? In my search for info to help with the repair, I found this video where the voltage regulators and their heatsink are removed and replaced: https://www.youtube....h?v=2rSlqt_VmjY
I only ask since I remember reading something about a faulty NES voltage regulator (same type used in the 5200) causing some similar problems.

Yes the bases are subtlety animated. It’s kinda cool.
Adjusting that potentiometer adds or decreases the color delay in the burst signal. It won’t harm any components. If it’s been tweaked, a darker an image could result. It’s an adjustment, specifically built in for color correction. Simple enough to check. Use your fingers.

There’s nothing wrong with your voltage regulators as they are. If your system powers up (which it obviously does) there is no fault here. The 7805s and the MJE220s are doing their jobs, and they would have zero impact on color reproduction. This is a go / no go condition. They work or they don’t.

Try some other games that don’t have such a dark background, like Dig Dug or Moon Patrol etc. to see if they are more vibrant than the dark background in Space Invaders.

Also, what does the system look like on a different Television? Same “dark/dim” problem? If this condition doesn’t travel to another TV, you can rule out the console

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Edited by atari-dna, Fri Jun 15, 2018 6:29 PM.


#9 atari-dna OFFLINE  

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Posted Fri Jun 15, 2018 6:20 PM

I forgot to mention,

The buck converter replacements are silly. These may be more electrically efficient, but they are oscillators—utilizing transistors and diodes to step up current and retard voltage.
Oscillators can introduce high frequencies and noise where you most definitely don’t want it—your DC power rail.
This concern doesn’t exist with a linear voltage regulator.
From an economy standpoint, the BC is ten times more expensive than the humble VR.



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Edited by atari-dna, Fri Jun 15, 2018 6:36 PM.


#10 -^CrožBow^- OFFLINE  

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Posted Fri Jun 15, 2018 9:09 PM

I forgot to mention,

The buck converter replacements are silly. These may be more electrically efficient, but they are oscillators—utilizing transistors and diodes to step up current and retard voltage.
Oscillators can introduce high frequencies and noise where you most definitely don’t want it—your DC power rail.
This concern doesn’t exist with a linear voltage regulator.
From an economy standpoint, the BC is ten times more expensive than the humble VR.



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Actually the DC-DC converter used in that video he linked to cost about $7 currently and is internally filtered to prevent the noise you are talking about. I have two of them in my 5200 which means the only heat inside of it now is that caused by the ICs themselves. And..there is no issues with the video or audio on my 5200.

 

Now..having said that there was 1 console where I did specifically have issues using these in it. That was my Sega Genesis. It worked just fine, but at least on some of the older games like Thunderforce II as an example, there was audible noise that wasn't there before. It sounded like the digital interference of the logic itself. So I install the higher amp rated linears back into my Genesis. All my other systems from my Intellivision, 2600s, 7800, 5200, and my Turbo Duo all have these Traco DC-DC converters in them. The power requirements are reduced, and there is little heat inside the consoles which can only extend the life of all the components inside them.

 

So...they are more expensive than a $1 7805 yes, but $7 each is small price if I don't have to worry about much else in the console going forward. 


Edited by -^CrožBow^-, Fri Jun 15, 2018 9:11 PM.


#11 atari-dna OFFLINE  

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Posted Sat Jun 16, 2018 5:26 AM

 
Actually the DC-DC converter used in that video he linked to cost about $7 currently and is internally filtered to prevent the noise you are talking about. I have two of them in my 5200 which means the only heat inside of it now is that caused by the ICs themselves. And..there is no issues with the video or audio on my 5200.
 
Now..having said that there was 1 console where I did specifically have issues using these in it. That was my Sega Genesis. It worked just fine, but at least on some of the older games like Thunderforce II as an example, there was audible noise that wasn't there before. It sounded like the digital interference of the logic itself. So I install the higher amp rated linears back into my Genesis. All my other systems from my Intellivision, 2600s, 7800, 5200, and my Turbo Duo all have these Traco DC-DC converters in them. The power requirements are reduced, and there is little heat inside the consoles which can only extend the life of all the components inside them.
 
So...they are more expensive than a $1 7805 yes, but $7 each is small price if I don't have to worry about much else in the console going forward. 


I chose to invest that same $14 in a desk fan, an easy upgrade to all consoles.


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#12 zylon OFFLINE  

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Posted Sat Jun 16, 2018 5:51 AM

I think you need a new RF modulator.

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#13 atari-dna OFFLINE  

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Posted Sat Jun 16, 2018 6:35 PM

Here’s a picture of a properly adjusted unit:
99f189edaf9142f4e7e9996f19fbf86c.jpg



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#14 BIGHMW OFFLINE  

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Posted Wed Jun 27, 2018 3:51 PM

Here’s a picture of a properly adjusted unit:
99f189edaf9142f4e7e9996f19fbf86c.jpg

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I would send my 2-port 5200 to atari-dna, he fixed and readjusted mine, back when I gave up on using an a/v/power-modded 5200 only due to a lack of compatibility with my VCS adapter (I still own both that a/v/power-modded 5200 and my deadstock non-modded 2600 Jr short rainbow just in case I need them), he also made sure I could use my VCS adapter and also tested it before sending it back to me, and although I'm not too much into the traditional RF buzzing of our non-modded (channel 2/3/4) vintage systems I enjoy the fact that I only need ONE system to do the job of both (and using only two wall plugs, one for the 5200 and one for my Insignia 39" TV), and yes, I DO have ROMs of the 2-port-hacks of Pitfall!, Mountain King and K-Razy Shoot-Out so I can play those too using my Atarimax Ultimate SD multicart and I also own an AtariAge Harmony Encore 2600 SD multicart as well as tons of games on both!!!

 

The only thing I wish for is that someone would make a 5200 clone that would work like a 2-port unit so I can also use my VCS adapter with it, as much as I like Big Sexy (and I have ever since getting my first 5200, a US-made 4-port, Serial No. 141101, back for my 17th birthday on May 19th, 1983), we can do without the excess bulk nowadays thanks :)

 

BTW, I also own two AtariAge/Pixels past Redemption 5200 interfaces (2 each) for 2600 controllers and also 7800 controllers, whenever I need that second fire button for games like Defender (for the smart bombs), and also some Wico Command Control 2600 ball sticks and 5200 joysticks and also the touch-tone-quality keypads too.

 

Just a few things left to get and that's it, all I need now are some Best Electronics gold CX24 joysticks, another gold CX52 stick to go with the one I own, and also to get my 2 CX53 Trak-Ball controllers fixed and/or recalibrated, as the bubble fire buttons do not work and the circuits on the keypads don't seem to work too well.

 

Also on my dream list are some 5200 paddle controllers which utilize the CX52 chassis with either a paddle or driving controller put in place of the joystick (for Kaboom!, Super Breakout, Tempest, etc.) and with the Best gold flex circuits already installed in them too (I have plenty of cores for the CX52 and CX24 sticks I want, and I just need price quotes to get two 5200 paddle controllers, like this one:

 

5200Paddle.jpg






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