Hello
I recently acquired a Overkal (Spanish clone of the Magnavox Odyssey), and have been tested in 3 TVs (one TV Thomson 21DC320 a Sony Trinitron 14 "and Thomson television early 80s), but the screen is completely black, is not the "square" representing the players, or the network nor the ball.
The Overkal've opened and I saw that the motherboard is in good condition (no burned parts or dirt or anything), the only thing worse is the battery connectors, which are quite rusty.
I've been adjusting various knobs there on the motherboard, but he has not served.
I wonder what component fails, if the signal type you use and my TVs are not able to support ...
PS: I have connected Overkal on batteries as a power transformer Atari 2600, and also shows exactly the same.
Sorry for my bad English, I used Google Translate to translate.
Thank You.