1976 Atari stunt cycle

Grhart1010

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I was recently handed down a stunt cycle that had been sitting for years. It would not function at all and only had 3.6 V after the regulator so I replaced that and now I'm getting a good 5 V. Now the game starts up and coins up and everything is good until the bottom of the screen where the buses take up the entire bottom row. They will not reset and the bike crashes before it even gets to the ramp every time.. with my limited experience and research I'm gathering it is an issue with a TTL chip. Anyone have an idea of which one could be causing this? Are the 74 LS series compatible?
 

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with my limited experience and research I'm gathering it is an issue with a TTL chip. Anyone have an idea of which one could be causing this? Are the 74 LS series compatible?

Considering the board is all TTL chips -- yes, it's an issue with a TTL chip.

Looks like OBJECT ZONE is stuck high... I'd try the 7474 @ J7 first.

LS74 might work, but you're better off using the original 74 series.
 
Thanks! New to arcade games… any recommendations on where to get the original 7400 series?? I see some on eBay but not sure how much I can trust them
 
No luck on the j7, replaced with original 74 series…

anyone know what the next best one to check would be?

Looking at the drawings, I was thinking N7. If not maybe L5 or L8??
 
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Considering the board is all TTL chips -- yes, it's an issue with a TTL chip.

Looks like OBJECT ZONE is stuck high... I'd try the 7474 @ J7 first.

LS74 might work, but you're better off using the original 74 series.
Replaced J7, H5, D2, E6, C8 all with no change..

I also noticed I don't have a score in the top left window for player one.. looking through the drawings maybe this could be related to the busses not resetting??

Any ideas? Lol
 
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