Atari Breakout - Composite Video

[Vond]

I am trying to fix my Walls Down arcade cabinet (which is an exact clone of Atari's Breakout) together with a friend of mine and we are having issues with the video signal.

It seems the signal we are getting from the PCB is neither PAL nor NTSC in terms of sync timing and high video output voltage (PP 0.5/2.5)
We hooked it up and got nothing more then horizontal stripes rolling vertically, but there definitely signs of game play components in the stripes displayed on screen!

Now in the (Atari Breakout) manual it says that "Because the composite video signal sent to the monitor by the game control circuitry differs in certain important aspects from the signal derived from commercial TV broadcasts, the picture appearing on the screen is unlike that of a home TV set..." does this mean the monitor itself adjusts the signal to something usable? (the original monitor in a Breakout cabinet is a B/W Motorola XM501 19")

The original monitor that was in my cab is absolutely broken so that is not an option at all.

Is it possible at all to hook up a Atari Breakout PCB to any T.V./Monitor that accepts a video signal?

[level42]

There IS no matter of PAL of NTSC because it's a a black & white signal.

PAL and NTSC are color encoding systems

Yes you can hook it up to anything with a composite video input.

What Atari means is that the composite video signal is much better in quality on a monitor. there is no HF (high frequency) antenna signals involved, hence no "snow" or other stuff that came with analogue broadcast signals.

[Vond]

Wow thanks for the fast reply
So that means that its basically a PCB problem I am experiencing at the moment?

[vernimark]

Check the board clock frequency first and then be sure you have all V and H signals

[Vond]

Will do that as soon as possible! Left the PCB + Power Supply at work.
I found the part in the manual referring to the clock and H-sync and V-Sync. Will dive into it
tomorrow. I'll keep you guys updated 

[PaulSwan]

You still need the monitor to support the correct timing. The composite signal contains both the pixel intensity and sync information encoded within it. That encoding needs to be compatible with the monitor you're trying to drive.

What monitor are you trying to use?

Paul.

[Vond]

Tbh I haven't got a monitor yet. We've been trying to get the signal on some LCD Screens where it displayed as white stripes and nothing more.
At home I had it hooked up to a NEC Multisync XM2960 (Also for testing purposes obviously as its a monstrous-wonderful scanline bearing beast!  )
I'm trying to get my PCB to work correctly and then i'll try to get a 19" Television for it that i'll get converted to a monitor for in my cabinet.

[PaulSwan]

I'm not sure you'll be able to get a B+W composite signal to work with any of those colour monitors. B+W composite is none interlaced (different sync) so they might not lock onto this type of video if they only expect a set of "standard" video signals. TV's may or may not support it (don't know on that).
However, most old CRT monitors with composite inputs might be able to display it. Philips CM8833 and Sony PVM's for example are known to work fine.
Paul.

[Vond]

I have got my hands on a Commodore 1701 (Monitor) which supports: PAL separate and PAL composite.
Might be worth a shot? I'll give it a try unless one of you strongly urges me not to or can already tell me outcome

[level42]

Yes that should work !

Hook it up to the Luma input my friend !




(and slide that switch to "REAR"...........duhhhhhh

[Vond]

Excelent!
Now I need to get my PCB back home again from my workplace in this horrid weather
I'll keep you updated! Thanks for the support!! 

[level42]

Horrid weather ? Where ? Nice and dry here...no frost, no snow, no ice......great ! 

[level42]

Hmmm, something just struck me: Where is the syncing when using Luma & Chroma ? I bet it's in the Luma signal (would make sense) but I never actually read about it.

The reason why I think this will work is that the Luma contains the brightness (or B/W) signal only. All the color is in the chroma signal.

[Vond]

No dice 

However, I think I got a glimpse of the ball every now and then:



I had to bend space and time to be able to get this picture of the suspected "ball" in action
André, you were right, I had to hook it up to Luma as suspected

Anyways, Back to the PCB I think, might be something off with the signal.

Btw, I have overlayed the two sides of the PCB in Photoshop (aligned perfectly!!) to be able to follow the physical paths over the board more easily
if anyone's interested in the PSD don't hesitate to contact me.

[level42]

Cool (the overlaying). Those processor-less boards are bitches.....