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Atari Stunt Cycle Repair Log


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When first powered up with +5v and Gnd there was just a faint image on screen, I found the 1k resistor on the composite video final output stage (which had been added by an op) was of too higher value for the TV I'm using.

A 5k pot was substituted and I was able to dial it in to get a good image up on screen.

There was some activity on screen but the bike was static on the left side top level and would just pop wheelies.

 

kZ9mHf2.jpg

 

I wired up the +12v (audio supply), -5v (audio and throttle supply), some switches for credit and start as well as 5k pot for the throttle.

In attract mode the bike would just keep going from left to right on the top level only.

When you credit the game up the audio would make a short buzz every time the bike returned to the left side of the screen.

After a bit of looking around the board and starting with the direction change issue, I found that if I injected a pulse into the 74194 on pin 1 at E1.

 

KmT0Q20.jpg

 

The game would start, you could accelerate and the cycle would go down two levels but when it jumped the buses, it would shoot upwards and go from the top of the screen and reappear just below the bottom line instead of landing.

 

I traced /CYCLE RESET A back to the 7404 at K8 and found there was no output at Pin 4.

 

yVFFYYT.jpg

 

I swapped it out with a used vintage 7404 and the game is now fully working.

:cool:

 

Edited by Kaizen
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Awesome. Cool game!

 

Now all you need to do is buy this on ebay and you're set!!!!!!!!!!!!

 

$_57.JPG

 

Bit pricey though. You could probably make your own??

 

I wonder how this game would do on site? I know I would want to have a good go at it.

Probably be a decent money spinner until each punter could jump all the buses.

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  • 3 months later...

I picked up another two Stunt Cycle PCBs a few months ago and finally got a chance to look at them.

 

The first board had a few IC's removed and was missing a capacitor for the engine sound.

After replacing the missing parts it was tested and is fully working. :)

 

The second board had some serious impact damage with broken chips, broken traces and was missing a few IC's and the crystal.

 

ufi3PlB.jpg

 

FLeMlTc.jpg

 

j3g6lu2.jpg

 

68SxuI9.jpg

 

2jOAdKM.jpg

 

After repairing the broken traces with Kynar wire and replacing the missing components the board booted up to this...

 

2bU500l.jpg

 

The first thing was to look at why there was some blanked out sections on the screen.

I thought the 7474 at A4 was faulty but turns out it was okay, I ended up finding a cut trace that supplies the clock to the 7474 at A5, after repairing it I now have the score working and the blanked sections are gone as well.

 

r5UUZ6V.jpg

 

 

More to come...

Edited by Kaizen
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A bit more probing around and I found the 9316 (74161) at K1 had the output on pin 11 stuck high, after replacing it the bike is now visible and the game plays normally.

 

oq964Dn.jpg

 

quP44v5.jpg

 

The next challenge is to find a solution for the broken ROM (I swapped one over from another board for testing) that contains the bike and bus images. It's an N82S115 PROM that most burners can't do. I'm looking at using a 2732A on a riser board.

The other PROM that was missing is an N82S123 which isn't as hard to program.

Edited by Kaizen
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Without checking the datasheet I can't say for sure... but it sounds like you're on to it.

 

Two chip select chips pins give power saving options/expandability to designs but it's not really important. /OE low will just keep the chip ready. And yes, other address lines should be low so you access the code.

 

Update : checked datasheet.

 

Transparent adress mode has strobe high. Like in schematic. So looks good. Good luck.

Edited by taito
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A bit more probing around and I found the 9316 (74161) at K1 had the output on pin 11 stuck high, after replacing it the bike is now visible and the game plays normally.

 

oq964Dn.jpg

 

quP44v5.jpg

 

The next challenge is to find a solution for the broken ROM (I swapped one over from another board for testing) that contains the bike image. It's an N82S115 PROM that most burners can't do. I'm looking at using a 2732A on a riser board.

The other PROM that was missing is an N82S123 which isn't as hard to program.

 

A Data I/O Series 22 with the 351A-064 adapter will do it. I have one but am in the States.

 

- - - Updated - - -

 

Yes... Tie the upper address lines low and the /CE line low.

 

In that circuit they aren't using the enables at all and are simply having the chip output data based on inputs with no controls being used.

 

Watch heat on the chip. I've seen EPROMs that tie lines high internally when making dual-BIOS chips for Colecovision consoles. If your ROM gets VERY hot, you'll want to tie those lines high/low using resistors to limit current - 220 to 330 ohms will be just fine.

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How good is that! Nice one! :)

 

Curious: What did you use to raise the little board? I've used wire wrap pins from Jaycar, but they are really expensive if you want to do a few. And did you use a socket on the main pcb to insert into or soldered directly.? :)

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Curious: What did you use to raise the little board? I've used wire wrap pins from Jaycar, but they are really expensive if you want to do a few. And did you use a socket on the main pcb to insert into or soldered directly.? :)

 

 

I bought a 32 pin machined IC socket strip from Jaycar.

 

tBV6qlU.jpg

 

Removed the pins and soldered them directly to the bottom of the proto board.

To line the pins up perfectly, I use a machined pin socket, insert the pins into it then line it up with the pads on the PCB.

Heres a clear shot of the same thing I did with the Pong Smaller Paddles mod.

 

1F3Vvvx.jpg?1

 

Just a standard 24 pin dual wipe socket on the PCB.

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  • 4 years later...

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