Adding composite video to a PONG system.

ral-clan · Post by **ral-clan** » Thu Oct 04, 2007 6:02 am

I had been reading on the internet how many people add composite video output to their old pong consoles. Apparently, it's really eassy. By merely finding the video signal wire that feeds the RF modulator with a signal and diverting this to an RCA jack (then connecting ground wires) you have a composite video output.

I tried it with two of my Radio Shack pong consoles (both clearly by different manufacturers when opened). It didn't work though. I got some sort of black and white video signal, but it is very garbled, and rolls around vertically.

Can anyone help me out? It almost seems like the signal needs some sort of SYNC to work with the video input on my NTSC TVs (I tried to different TVs by the way).

Too bad it wasn't as straightforward as it seems for other people's PONG systems.

nbla000 · Post by **nbla000** » Thu Oct 04, 2007 6:42 am

I think to have an Odissey 2001 clone that use these chips:

Model: MAS SIL-COM

LM1889N /\/ 810 9x2=18 Pin
MM-57105N /\/ 811 12x2=24 Pin (Main Chip)
MM53114N /\/ 820 4x2=8 Pin

I'm not hardware expert but an Audio/Video repairer says me that is not possible to add RC output for this Pong clone model because the video signal in RF format exit from a pin of the main chip, i don't know if is true or simply he don't want to spend time for this work.

I wish to add Audio/Video RC output to my Pong clone, someone think is possible ? other information required ?

I may send the internal board photo if required.

carlsson · Post by **carlsson** » Fri Oct 05, 2007 5:24 am

If the video circuit outputs RF on its own instead of using a separate RF circuit, I think your repairman could be correct. You would need to reverse-engineer the circuit in question, to see if you can tap another video signal at some point, but it doesn't sound like an option...

nbla000 · Post by **nbla000** » Fri Oct 05, 2007 5:33 am

carlsson wrote:If the video circuit outputs RF on its own instead of using a separate RF circuit, I think your repairman could be correct. You would need to reverse-engineer the circuit in question, to see if you can tap another video signal at some point, but it doesn't sound like an option...

Thank's Carlsson but i'm not able to reverse-engineer the circuit or to see if what you say is right, i will take some images may be can help you.

carlsson · Post by **carlsson** » Fri Oct 05, 2007 6:09 am

Well, I'm no electronics guy neither. The other people in this forum will be able to help you further. I know as much as if there is one chip that generates a video signal (perhaps the LM1889 ?) and that chip only has a RF output on one of its pins, you may be in tough luck. As an alternative, you could try a RF to composite splitter, which though will not result in a better image quality than the RF signal already has.

nbla000 · Post by **nbla000** » Fri Oct 05, 2007 9:36 am

OK, here there are some detailed photos of my PONG clone.

ral-clan · Post by **ral-clan** » Fri Oct 05, 2007 9:52 am

My pong console uses the very common and famous AY-3-8500 (NTSC?).

http://www.pong-story.com/gi8500.htm

That page has a pinout diagram.

Interestingly enough, in my poking about the board to find pinouts for video, I did discover all the seperate video outputs (for the ball, paddles, etc.). You can see each one on the screen by itself if you connect the TV to that point on the board, but as I mentioned above, it is quite skewed to the side and rools - I am sure there is some sort of sync problem.

I will upload pictures of my console soon.

ral-clan · Post by **ral-clan** » Sat Oct 06, 2007 6:49 am

Here is the schematic for a PONG game using the AY-3600-1 chip I have. It is basically the same as the PONG game I own:

You can see the video signal from following pins are merged to some sort of OR gate at the bottom of the schematic:

Pin 6 - ball video
pin 9 - left paddle video
pin 10 - right paddle video
pin 25 - playfield video

Then the output of pin 16 (SYNC) is sent to another sort of OR gate (I don't understand why - I would have thought an OR gate needs at least two inputs to be useful).

Then both the four merged video signals and the SYNC signal go through respective resistors and are merged, then sent to ground and to the RF modulator.

I am very much a novice in electronics, but this is what I can glean from the schematic. So you WOULD think that simply taking this signal before it goes to the RF modulator would result in a B&W composite video signal.....but it's all jumbled.

Any insight?

wiskow · Post by **wiskow** » Tue Oct 04, 2011 7:46 pm

ral-clan, did you ever solve this mystery? I have an old Sears Hockey-Pong system that I'd love to set up with composite video instead of having to use the game-TV switch box.

ral-clan · Post by **ral-clan** » Sun Oct 23, 2011 10:51 am

No, I never got it to work. Sorry.