Wavy video interference ?

[Charlie_]

My 7800 was having an issue with the RF jack. I think it had a broken solder joint. Lightly moving the wire near the jack would make the signal come and go. So, because I could not see a way to open the modulator and fix that, I removed it and installed a simple Retrofixes composite AV mod. It seems to work well enough except for this. When ever the screen is using a darkish blue (like the maze in pac-man collection) or magenta(ish) color every so often I can see noise or interference in the color. Sort of vertical-diagonal waves that slowly move horizontally. It is very distracting. It comes and goes almost like it is on a timer. I've only really noticed it in 7800 games. I replaced the power supply with the Best Electronics one. All the other systems on the same input through the same switch don't have the issue. What would be causing this cycle of interference?

 

[John Stamos Mullet]

7 minutes ago, Charlie_ said:

My 7800 was having an issue with the RF jack. I think it had a broken solder joint. Lightly moving the wire near the jack would make the signal come and go. So, because I could not see a way to open the modulator and fix that, I removed it and installed a simple Retrofixes composite AV mod. It seems to work well enough except for this. When ever the screen is using a darkish blue (like the maze in pac-man collection) or magenta(ish) color every so often I can see noise or interference in the color. Sort of vertical-diagonal waves that slowly move horizontally. It is very distracting. It comes and goes almost like it is on a timer. I've only really noticed it in 7800 games. I replaced the power supply with the Best Electronics one. All the other systems on the same input through the same switch don't have the issue. What would be causing this cycle of interference?

 

That's common on that type of composite mod, and there really is no fix for it. I would suggest getting a UAV mod in there. The Composite from that has no interference, and the S-video is perfect, if you have that option.

[Charlie_]

1 minute ago, John Stamos Mullet said:

That's common on that type of composite mod, and there really is no fix for it. I would suggest getting a UAV mod in there. The Composite from that has no interference, and the S-video is perfect, if you have that option.

I see! Thank you.

Will the removal of the RF modulator and the few resistors done for this mod interfere with the UAV install?

 

[+-^CrossBow^-]

1 hour ago, Charlie_ said:

I see! Thank you.

Will the removal of the RF modulator and the few resistors done for this mod interfere with the UAV install?

 

No you should be okay assuming that the audio resistors of R5 and R6 are still in place? The taps for the UAV are taken at the bottom of the resistors so it doesn't really need them in place. 

 

Specifically, the issue you are seeing is because of the two chroma (color) signals from the 2600 TIA side and the 7800 Maria side being combined together. This is only seen on 7800 games. The older LHE mod suffered from this as well, and the only real fix on that, was to wire in a switch to disable the color input from the TIA when playing 7800 games. 

 

The UAV isolates the two better to help prevent that.

[John Stamos Mullet]

21 minutes ago, -^CrossBow^- said:

No you should be okay assuming that the audio resistors of R5 and R6 are still in place? The taps for the UAV are taken at the bottom of the resistors so it doesn't really need them in place. 

 

Specifically, the issue you are seeing is because of the two chroma (color) signals from the 2600 TIA side and the 7800 Maria side being combined together. This is only seen on 7800 games. The older LHE mod suffered from this as well, and the only real fix on that, was to wire in a switch to disable the color input from the TIA when playing 7800 games. 

 

The UAV isolates the two better to help prevent that.

Thing is - I used to see that on 2600 games too, specifically Frostbite, and Pressure Cooker. It's the dark blue background color. This was with multiple 7800 consoles with variations of the Best/Easier composite mod.

[Charlie_]

41 minutes ago, -^CrossBow^- said:

No you should be okay assuming that the audio resistors of R5 and R6 are still in place? The taps for the UAV are taken at the bottom of the resistors so it doesn't really need them in place. 

 

Specifically, the issue you are seeing is because of the two chroma (color) signals from the 2600 TIA side and the 7800 Maria side being combined together. This is only seen on 7800 games. The older LHE mod suffered from this as well, and the only real fix on that, was to wire in a switch to disable the color input from the TIA when playing 7800 games. 

 

The UAV isolates the two better to help prevent that.

Thank you for the reply and explanation! 

 

Where can I purchased a UAV? I checked ebay and didn't find it.

 

Here is a picture of the Retrofixes mod I installed. I added a resistor and then a pot to the audio to balance it with the Pokey audio. Does UAV balance with audio itself?

 

[+DrVenkman]

2 minutes ago, Charlie_ said:

Where can I purchased a UAV? I checked ebay and didn't find it.

Note that TBA was closed for inventory and to catch up on backorders but now also is being affected by Covid so be patient.  

 

https://thebrewingacademy.com/collections/ultimate-atari-video-uav

[Charlie_]

21 minutes ago, John Stamos Mullet said:

Thing is - I used to see that on 2600 games too, specifically Frostbite, and Pressure Cooker. It's the dark blue background color. This was with multiple 7800 consoles with variations of the Best/Easier composite mod.

I see noise in the 2600 picture. Specifically the blue in Seaquest. It is different though as it seems the whole screen gets a uniform interference for a few moments and then clears up, comes back, and so on. It is not that distracting. With 7800 games the interference is like ocean waves that wash over the color on screen.?

 

Thank you for the replies! If I can get my hands on a UAV I'll attempt the install.

The 7800 was sort of a secondary Atari system to me as I am a big 5200/VCS user.

Now that I've been playing it more and more, I find myself going to the 7800 a lot!

 

 

[Charlie_]

5 minutes ago, DrVenkman said:

Note that TBA was closed for inventory and to catch up on backorders but now also is being affected by Covid so be patient.  

 

https://thebrewingacademy.com/collections/ultimate-atari-video-uav

Thank you for the link! I was able to order the Kit.

 

[+-^CrossBow^-]

Well, the UAV can be used in a 5200 with great results as well!

 

The audio you should be okay on and won't need to mess with it. The UAV doesn't have anything on it for audio so that has to be handled separately anyway.