For Techies Only!

[Benzman66]

Was working on a newly acquired console today and ran into a unusual situation. When you use any type of RF cord, the picture is a little fuzzy, but if any of you remember the old style Atari cords with the filter box on the end, when that is used, it has a beautiful picture. Can't be the RF cords as I tried 15 of them and they work perfect on other boards, plus I changed the line filters, and the problem remains.

 

Any other techies out there have solutions?

[Synthead]

Was working on a newly acquired console today and ran into a unusual situation. When you use any type of RF cord, the picture is a little fuzzy, but if any of you remember the old style Atari cords with the filter box on the end, when that is used, it has a beautiful picture. Can't be the RF cords as I tried 15 of them and they work perfect on other boards, plus I changed the line filters, and the problem remains.

 

Any other techies out there have solutions?

 

You know, my 2600 never had a good picture on the RF output. There has always been a lot of snow and I feel that the picture was very weak. When I first bought it, it just so happened that my buddy who I was hanging out with at the time had an RF amplifier and it helped clean the picture up a bit, but not anywhere close to my satisfaction. I later did a little soldering and modded it for direct outputs without cutting up the system in any way, shape, or form. I cut up some Radioshack RCA splitters to have three female-RCA-terminated dongles sticking out of the hole the RF cable normally extruded through to provide composite video, analog audio, and the original RF feed. It works very, very good and has an amazingly colorful, rock-solid picture now.

 

That was my solution ... but if you want to get into the really techie side that I avoided ...

 

I have to be ambiguous in answering this as I avoided the problem from the get-go, but looking back, there are only two things that could cause the problem: a defective source or insufficient shielding. In other words, your signal is not strong enough from the beginning on the component level, the components that produce the signal are defective, or the signal is fine but there's too much interference being captured as it sends the signal to your television. Check all your traces for foreign material like spilled drinks, bugs, or any debris, check your electrolytic capacitors to make sure they're not dried up of oil, look for damaged components, and check for cold, weak, or broken solder joints. If everything is clear, make sure that everything is properly grounded (including your television) and that there is a consistent shield that is effectively grounded throughout the entire system.

[potatohead]

Get some really well shielded cable. There is a lot of crap out there. My Atari works best with a cable with a lot of shielding. The stock Atari cable has a copper core, plastic insulator, then foil, then wire mesh, finished by the outer plastic cover.

 

Many of the cheapo RF cables have those things, but scrimp on the inner conductor, offering fewer strands, and the wire mesh is weak. Look for a wire mesh that's very full, with the foil underneath.

 

Finally, get a shorter length, and or make a ferrite filter. You can buy the rings in many places. Get a 1 - 1.5" inner diameter one, and loop the cable through a few times, until you like the picture.

[Benzman66]

 

 

I have to be ambiguous in answering this as I avoided...

 

That's the funny thing, the board is in great shape, no dirt, bugs, rust, etc. I checked everything all over and there are no signs at all of damage, corrosion, but you are right, it seems there is not enough "juice" to get the signal perfect to the tv, unless I am using the cord with the filter box on the end, but I really hate trying to fit that in the console.I changed the caps near the rf modulator, but no difference.

 

Any other thoughts on this from anyone?