Sprint issue

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I’ve finally got another crt for my sprint 2
I’ve had the pcb repaired but it’s showing this image
Has anyone any experience of this and could help please
I was reliably told it was a problem from the coin door wiring
Had anyone a pic of their coin door wiring they could share so I could copy theirs
 

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Lurch666

Lurch666

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If the game is running then it's not the coin door wiring.
If the coin doors aren't wired properly the game doesn't reset properly.
Looks like you have another problem.
I'm trying to fix a sprint 2 PCB myself but it's been put on one side while I do other fixes since mine doesn't boot even with the coin doors wiring correct.
 
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Cool thanks .its just frozen on that image
If you do get back to the other sprint your repairing and mine could help you or you could help with mine
Gives a shout please .
 
Lurch666

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Not sure then. It looks to me like it's getting somewhere then locking up but I don't have much experience.
The point of the coin mechs is that they have normally open contacts and normally closed contacts (check the manual) if the normally closed contacts aren't connected that causes the freeze so check your normally closed connections.
EDIT:Just checked-It's H and J on the edge connector-make sure they are connected to GND.
 
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no need, you just need to add an extra 74ls04 to the board to create inverted coin signals on games with 3wire coinswitches.
however, old atari boards are usually a socket or tarnished pin problem
i assume you recapped the power section?
 
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so i have had this before on maybe gorf or the sega g80 rack - cant remember which.
normally you have a coinline that is high (from a pullup resistor) and the switch pulls it low
on 3wire games you have a second line that is low and goes high when a coin goes in.
so the 2 must be oposing each other.

if you connect a regular coinmech to the normally high input and also run that to an inverting buffer and then feed the output into the normally low coin input then it solves the problem.

i think the 3wire system was intended to prevent noise or piezo generators etc from gaining credits
 
Lurch666

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That's so a normal coin mech can work with a three wire system but with sprint if the NC isn't connected to GND the game doesn't run so that's a different issue.
 
Lurch666

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No unless you do what you suggested or use a three wire system.
But the issue here is neither of our PCBs are working so coining up is not an issue at the moment.
 
Lurch666

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So since it fixed mine I'm wondering if this could be a ram issue.
It looks like you have corrupt characters at the bottom of the screen. Is the ram in sockets?
It's the eight 2102 chips at locations F4,H4,J4,K4,F3,H3,J3 and K3.
 
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Lurch666 said:
So since it fixed mine I'm wondering if this could be a ram issue.
It looks like you have corrupt characters at the bottom of the screen. Is the ram in sockets?
It's the eight 2102 chips at locations F4,H4,J4,K4,F3,H3,J3 and K3.
Click to expand...

Those do look to be socketed on mine don’t they ? If you can tell from pic I had on phone
 

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Lurch666

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New theory.
I managed to reproduce what you are seeing with my sprint PCB.
I disconnected the coin inputs (H and J on the edge connector) that need to be grounded for the game to run and got a screen of partial garbage.
If I briefly connected those inputs to GND the game would run for a bit then stop again.
Since the screen refreshes from top to bottom it draws the track and positions the cars from top to bottom and I could get it to draw most of the track,position the cars in the correct place then stop just before it finished drawing the screen leaving just a line of garbage at the bottom. Just like how your game appears in your first post.
So you might have a situation where the GND to the coin inputs is somehow only being held down for a brief while (maybe down to the way the PSU works) then because the inputs are no longer being held to GND the game is stopping with most the screen drawn.

So it could be an issue with GND going to pins H and J.
 
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