Scrambled video on OutRun

mikenj73

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The video on my outrun is scrambled. It keeps scolling vertically but looks like it has diagonal lines running through it. I'm pretty sure it's not the monitor, because it's happened on two other monitors I've tried. Any advice on what to try next?
 
You have connected multiple monitors to the subject OutRun PCB. Are any or all of those monitors known to work properly? (i.e. do they display a normal picture when connected to other game boards?)

Does the OutRun PCB seen to generally function, other than the video output? (i.e. can you coin it up, start a game, hear the music and sounds, accelerate, turn off the road, get the steering wheel to shake, etc?)

Can you post a picture of the "scrambled" screen? And identify the monitor model(s) you've tried using?
 
You have connected multiple monitors to the subject OutRun PCB. Are any or all of those monitors known to work properly? (i.e. do they display a normal picture when connected to other game boards?)

Does the OutRun PCB seen to generally function, other than the video output? (i.e. can you coin it up, start a game, hear the music and sounds, accelerate, turn off the road, get the steering wheel to shake, etc?)

Can you post a picture of the "scrambled" screen? And identify the monitor model(s) you've tried using?

I have used other monitors that have worked fine with other games. This is at least the 3rd monitor that I have tried, and all of them have the same scrambled picture on them.
The game seems to play fine otherwise. I can coin up and play the game, and all the sounds work. The picture is the only real issue at this point. I couldnt get a pic of the monitor chassis or the make or model, but it is out of a Pole Position if that helps.
One other thing i noticed: it seems there is a part missing from one of the boards. I'm not sure it is causing the screen issue, but i figured id mention it (in pics below).
 

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I have used other monitors that have worked fine with other games. This is at least the 3rd monitor that I have tried, and all of them have the same scrambled picture on them.
The game seems to play fine otherwise. I can coin up and play the game, and all the sounds work. The picture is the only real issue at this point. I couldnt get a pic of the monitor chassis or the make or model, but it is out of a Pole Position if that helps.
One other thing i noticed: it seems there is a part missing from one of the boards. I'm not sure it is causing the screen issue, but i figured id mention it (in pics below).

I agree with the assessment that this looks like a sync issue. It's good that the board seems to fully work other than this problem.

There are a few possibilties to consider:
0) a sync problem with the monitor. Seems extremely unlikely, as you've tried several known-working monitors.

1) (no offense intended, but perhaps) you are incorrectly connecting the monitor. The game PCB outputs a composite sync, which is both vertical and horizontal sync combined onto a single wire. Some monitors need this hooked up slightly differently. Often, a single (composite) sync wire goes to the monitor, and it is "looped" to connect to both the H & V sync inputs of the monitor. As Bob describes, the K7000 is a little different; composite sync should be connected ONLY to the H input on that monitor. Read up here: http://arcadecontrols.com/BBBB/sync.html

2) A connector/wiring problem between your PCB and the monitor. Find the video output on the PCB; check the edge connectors (both the PCB fingers, and the pins inside the connector). Check the other end. Check continuity from one end to the other on each pin. Check the connectors/pins on the other end (that connects to the monitor) too.

3) A PCB problem. These come in a few sub-varieties:

3a) physical damage; a scratch or gouge or something else has broken a the trace with the sync signal on it. If it suddenly stopped working, without possible cause of such damage, this is unlikely. But if someone was working inside the cabinet, or doing anything which could have caused damage... look carefully for it.

3b) the 74LS125 @ IC91 on the video (bottom) PCB. This buffers the sync signal just before it leaves the PCB.

3c) We really hope you've found the problem before here. Because almost the only other thing it could be (IMHO) is the large custom IC 106. It generates the sync signal. However, it's likely almost impossible to find, and expensive/difficult to replace. If the problem isn't fixed before (3b), it's pretty much a lost cause.
 
I will check all the things you mentioned to make sure i didnt miss anything. i went ahead and ordered the missing capacitor for the pcb. hopefully that's all it is. thanks for the help!
 
I will check all the things you mentioned to make sure i didnt miss anything. i went ahead and ordered the missing capacitor for the pcb. hopefully that's all it is. thanks for the help!

Oh, yes, I forgot to mention the cap.

Feel free to replace it, of course. But I don't expect it to effect your problem. Those are just caps to filter noise off of the 5V line for TTL ICs in that section of the board. There will likely be several of them per PCB. Anyway, that one is on your top (CPU) PCB, and the video output is on the bottom PCB. There's a small chance it's the problem... but my estimate is that it's unlikely to be.
 
UPDATE: I have figued out the scrambled video issue (mostly). It turns out that I did not have the horizontal and ground wires attached to the correct terminals. I got it working to the point that you can see the screen and play the game. I now see that i have some graphics issues somewhere in the board, I guess. You'll notice it in the trees on the high score screen, the hand is all but missing on the music screen, and it's pretty much all over the place during the game. I carefully removed all the chips off the bottom (video) board and cleaned the legs and put them back on the board, but the problem still remains. I am still waiting for the capacitor to be delivered to replace my missing one (mentioned in previous posts), so I'll post another update when i get that done.
 

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I was out in the garage messing with this thing again. I went into diagnostics and found that IC 95 is showing up as bad. Could this be causing the video problem in the pics above?
 

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I was out in the garage messing with this thing again. I went into diagnostics and found that IC 95 is showing up as bad. Could this be causing the video problem in the pics above?

IC95 (on the bottom board) looks to be a palette RAM. So in short, yes, a bad one will likely cause wacky video problems.
 
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