Odyssey 2: Black picture (but has audio)

[Jron]

Greetings!

 

I just acquired my first Odyssey 2 console this weekend while at the Retro Game Con in Syracuse. Unfortunately, my adventures with KC Munchkin are on hold while I figure out a video issue.

 

When turned on the picture is black with or without a cartridge in it. I can hear the audio from the game when I press a number key so I know code is being executed and that the CPU is probably fine.

 

I've reset both CPU and AV chips in their sockets a few times. I also re-flowed the socket pins. I also added a composite amp to remove the RF modulator from equation. I get audio through it but the video is still black through composite. The TV does see a composite video signal.

 

Next I want to re-flow some more pins, check some continuity, signals (AV and Color chips), and maybe replace the electrolytic caps (the seem ok though).

 

Before I do that I wanted to tap the knowledge base here. Does anyone have any recommendations on how I should go about debugging/fixing this? I do have an oscilloscope available.

 

Composite amp schematics:

http://solarfox.triluminary.net/hwh_o2avc_p2.php

 

Odyssey 2 schematics I'm using:

https://console5.com/wiki/Odyssey2

 

I found this thread, but it was a dead-end:

http://atariage.com/forums/topic/170540-magnavox-odyssey-2-picture-problem/