Vader Showing Dark Vertical Lines In Certain Games

[thecrypticodor]

Interference like that can be caused by bad power filtering. The first thing that I would try is replacing the filter caps. That big 2200uf 16v the .1uf 100v underneath it and also the 4.7uf 35v near the modulator.

Edited June 16, 2015 by thecrypticodor

[7800]

I noticed the 45 degree RCA adapter has a longer stinger than the stock RF cable plug. Could that have anything to do with it? Could that be trimmed down so it fits all the way in the RF jack?

[DanOliver]

I'm as from a hardware dude as one can get get...but here's my experience.

 

If you move the cable around and the pattern on screen changes then the cable is picking up the (some) of the interference and maybe a different cable and/or ferrite can help.

 

If walking around the unit changes the pattern the interference source is likely some other electrical device in the room.

 

Because the pattern doesn't change I'd assume the cart or VCS is producing the interference and also picking up the interference and sending out through the cable. It was a little before my time but I think first games from Apollo produced interference and they had to add a shield. Later I think they changed the board layout to reduce interference and that saved the cost of having to add a shield. All this shield stuff is more art than science. It's not really a matter of encasing everything in steel. Like you found with the "better"cable. In this case I assume the interference signal is transmitted from the VCS thru the cable. So a better cable keeps the interference signal better intact and what you see on screen is worst. The cheaper cable can pick up other interference and maybe cancel out some of the original interference and produce what you see as a better screen image but really just might be more washed out because of the way vision works. Human vision is very strange and not what most people think. Never believe what you see.

 

So if you can add a shield to the cart, to ground like with a piece of wire and then move the shield around the cart while running and observe the pattern on the screen you might be able to find the right position to grab the interference signal and send it to ground before some other part of the machine can pick it up. A better name for "shield" imo would be "antenna". You're not blocking interference, you're trying to direct it to ground before it goes to some other place you don't want.

 

If you don't see any change on screen while doing this to the cart I would assume the interference in coming from the VCS motherboard. You can do the same deal to the motherboard. Could be the interference is being produced in the VCS and picked up on some carts so fixing it for one cart might not fix it for all carts. And there are degrees of "fix".

 

Of course grounded metal...electric...running units...I assume you understand the risks. If not, you will.

Edited June 19, 2015 by DanOliver

[thecrypticodor]

 

I took some pictures of the effect of the 4.7uf capacitor taken in and out of circuit. So If I were you I'd definetly try replacing that cap.

 

 

 

My LCD has really long image retention so ignore the obvious Minecraft HUD.

[Skippy B. Coyote]

I noticed the 45 degree RCA adapter has a longer stinger than the stock RF cable plug. Could that have anything to do with it? Could that be trimmed down so it fits all the way in the RF jack?

 

Indeed it can! Just this afternoon I filed down the plug on the 90° adapter so that it was the exact same length as the original stock plug, allowing it to be fully inserted into the RCA jack on the board for a solid flush fit. Sadly that did not reduce the interference at all, but it is nice to have a more secure connection between the RCA cable and the board.

 

 

 

I took some pictures of the effect of the 4.7uf capacitor taken in and out of circuit. So If I were you I'd definetly try replacing that cap.

 

IMG_1528.JPGIMG_1530.JPGIMG_1531.JPGIMG_1532.JPG

 

 

My LCD has really long image retention so ignore the obvious Minecraft HUD.

 

Thanks a lot for the advice! I wanted to wait until the ferrite beads had arrived from Hong Kong and I tried installing them on both ends of the shielded cable before I replied to this thread, but as you probably expected the ferrite beads did not get rid of the strange interference patterns. What they did do though was clean up the video signal so that all the colors and pixels sharpness look quite a bit better than they do with the stock cable, even if though odd interference pattern still remains.

 

Another thing I've noticed is that the interference pattern (which is very similar to the one pictured above) actually shows up in every single game I play on the VCS, it's just very obvious in some of the games (such as Princess Rescue, Halloween, and Reactor) and difficult to see in others. But, if I take a really close look at the screen, it's still there in every game. I think it's pretty safe to say that the problem is indeed the above mentioned capacitor.

 

At this point I have a decision to make. I don't know how to solder, I don't own a soldering iron, and even if I did I have no idea where the 4.7uf capacitor is located on the board or where I should go to buy a replacement once the original has been de-soldered and removed. So I can either search around online and attempt to figure all that out then buy a soldering iron and the needed accessories to perform the repair, or I can just go on eBay and spend $30 to buy a new bare bones Atari 2600. It seems like it would be relatively the same price regardless of which option I choose, and while buying an entirely new Atari 2600 would be the easier option I think in the long run I'd probably be better off learning how to solder and having the tools to do future soldering work should it be needed. It just seems like the smart way to go, since I'm guessing this will not be the last time I find a capacitor in need of replacement in one of my many different retro systems.

 

So... any recommendations for a good budget friendly soldering iron kit and somewhere to buy a replacement 4.7uf capacitor?

[7800]

If you want to send out your unit to get fixed, talk to Zylon. He recently did some work on my H6, he might be willing to help.

[thecrypticodor]

 

I pulled out my four switcher and tried Reactor on it and it does displays a bit of that interference pattern. Not nearly as bad as the picture I posted which is was on a six switch with that cap out of circut yet it's there. I replaced all the caps in it a number of years ago so that isn't the problem. That pattern isn't noticeable on any of my other systems including my 7800. So some degree of those lines could actually be normal for four switchers.

[+RichG1972]

Another thing you might try as well is turning the brightness and contrast of your TV down Jin for one, and for 2 if the TV has an AUTOPROGRAM setting to lock onto channel signals, run it with the Atari powered ON, it will clear up any remaining static

[+RichG1972]

To properly calibrate the colors on your TV after running the AUTOPROGRAM setting of it, use these bars, if not calibrated correctly, below the red line and black rectangle 3 black bars will be visible, turn your brightness and contrast down until only ONE of those 3 bars shows, then turn the color setting down until the colors do not seem to "glow" like they are trying to jump off the screen. Then you will be playing Atari at the correct setting, not only that but this extends the life of your TV as well

Edited June 28, 2015 by RichG1972

[7800]

Another thing you might try as well is turning the brightness and contrast of your TV down Jin for one, and for 2 if the TV has an AUTOPROGRAM setting to lock onto channel signals, run it with the Atari powered ON, it will clear up any remaining static

 

To properly calibrate the colors on your TV after running the AUTOPROGRAM setting of it, use these bars, if not calibrated correctly, below the red line and black rectangle 3 black bars will be visible, turn your brightness and contrast down until only ONE of those 3 bars shows, then turn the color setting down until the colors do not seem to "glow" like they are trying to jump off the screen. Then you will be playing Atari at the correct setting, not only that but this extends the life of your TV as well

 

Very interesting.

[Keatah]

A higher quality cable with lower losses will pick up artifacts generated by the equipment. Whereas a cheap cable has losses and subtle interference doesn't have the strength to make it through.

[John Saeger]

This is kind of an old topic but I was doing a composite video mod to one of my 2600s and I saw the weird pattern in Reactor. I thought it was so unusual I searched for Reactor and found this thread. In any case I found it to be pretty easy to get rid of the pattern. Just add some large electrolytic capacitors to the main board. I have a bag of 470uf capacitors so I used those. Simply putting a capacitor across the voltage regulator goes a long way toward making the pattern go away. Another good place is right across the TIA chip between pins 1 and 20, and at the same time putting one in parallel with the 4.7 uf capacitor near the RF modulator. Another cap between pins 2 and 4 of the 6507 did no harm but by the time you get to this point the video is pretty much squeaky clean. Of course my 2600 no longer has the RF modulator. I removed it and used the left over holes as a convenient spot to plug in my transistor, so, as usual, YMMV.

 

Having said all of that I decided I liked it better when I could see the weirdness so I took the capacitors back out again. But to each his own and I may change my mind later. Or maybe I'll set up one 2600 with capacitors and have another one without. We'll see... It's only a hand full of games where the pattern is particularly distracting. And by the way you can add Jedi Arena, Qbert, and Planet Patrol to the list of particularly weird games.

 

So what this says to me is that the weirdness is caused by noise on the power supply lines leaking into the (analog) video signal. It also tells me that some carts cause more noise than others. For the folks who enjoy writing games and packaging them in carts I think it would be nice to figure out why some carts are different. Maybe some carts need a bigger decoupling capacitor depending on what kind of ROM chip they are using. For example, maybe Reactor would be quieter with a larger, possibly electrolytic capacitor in parallel with the 0.1uf capacitor that seems to be on that board. But I'm just guessing...