I bought a Gottlieb Circus project machine. So far I have gotten the CPU working again with the help of Marco Alba's test chip - Shout-out - Great stuff!

However now, when you turn the game on, it waits 5 seconds and then you get the attract mode. But nothing else, no coin-up, no response from the test switch, or the tilts. The Displays show "000000" but never switch to a high score. ALSO- the credit display has nothing on it - Ever. So there you have it. I was hoping to at least get the sound board to play some notes of encouragement, but not knowing ANYTHING about Gottlieb - System 80 or otherwise - I'm at a loss for where to go from here. I've tested the voltages, and all seems well.

Can someone point me in the right direction? thanks!

-Brian

#2 7 years ago

MAX

mbaumle

Pinside member

Gloucester Township, NJ

8y 119K 4,200 18 32

I know relatively little about System 80 games, besides the fact that they're rife with floating grounds and other grounding issues.

Pinwiki has a pretty good section on that. Perhaps start there.

#3 7 years ago

YCV

Arcane

Pinside member

Raleigh, NC

7y 54,550 889 6

Doesn't the sound board have a test button that you can press to hear all the possible tones?
I know the System 1 2nd generation sound board and the Janin S1/S80 compatible sound board have that feature.

If a System 80 is like a System 1, all zeroes on the display means that it is in SLAM mode and that the program has not started yet. Again, I know nothing about the SYS 80 and I am just extrapolating the System 1 behavior.

Yves

#4 7 years ago

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ForceFlow

Pinside Moderator

9y 236K 31,333 268 14

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Open_Slam_Switch

Some people like to perform a slam switch modification on the MPU, but I prefer to fix any actual problems with the slam switch and tend not to do the mod. However, adding a temporary jumper might be a good, quick troubleshooting step for determining if this issue is a slam switch issue:

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Slam_Switch_Modification

#5 7 years ago

CJB

Topher5000

Pinside member

Thorold, ON

10y 45,300 900 1

Yeah, I was going to do the slam switch mod on my 80b, but I use it to get out of the menus.

#6 7 years ago

BDP

bdPinball

Silverballs

8y 42,900 616

I don't THINK it's the slam switch - If it's a slam switch problem you get the "Wavy" zeros problem - Right? and the game never boots.

This game boots, and goes into attract mode.

However it doens't respond to any of the switches - Test, Tilt, Coin-up, etc. It DID respond when I flipped switch - 28? The switch that controls whether or not the game should display "Attract Mode" where the playfield lights light sequentially and such. hahah, I'm pretty sure everyone reading this knows what attract mode is!!

Marco on my original thread about the motherboard suggested that it might be one of the 74LS chips that have something to do with the switch matrix. Hell, with all the other chips I've had to replace on this motherboard (I was thinking of calling it a MF board) but yeah- I've replaced the 6502, all three 40 Pin Riots (what a riot that was), and then the 4069, and 4081 chips. That was just to get the board to this point. He gave me some pretty good suggestions on how to test the switch matrix to see if that's getting the "attention" it needs to. Heh.

Thanks everyone!

-Brian

EDIT- Yes, or, I mean no, it's not the Slam Tilt. I know that is the problem a lot of the time on these games, but I tried holding the slam tilt open and sure enough, I got the Wavy Zeros, and the game woudln't boot. Just wanted to clarify that.

Post last edited 7 years ago: “Slam tilt causes Wavy Zeros, and the game WILL NOT boot.”

#7 7 years ago

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ForceFlow

Pinside Moderator

9y 236K 31,333 268 14

OP
Quoted from bdPinball:
Marco on my original thread about the motherboard suggested that it might be one of the 74LS chips that have something to do with the switch matrix. Hell, with all the other chips I've had to replace on this motherboard (I was thinking of calling it a MF board) but yeah- I've replaced the 6502, all three 40 Pin Riots (what a riot that was), and then the 4069, and 4081 chips. That was just to get the board to this point. He gave me some pretty good suggestions on how to test the switch matrix to see if that's getting the "attention" it needs to. Heh.

There is one 74xx chip that the tilt switch passes through. I had one board a while back with similar symptoms until I replaced that faulty chip. It may have been a 7404, but trace out the signal path for the switch to find the chip in question.

[edit]: Ok, I looked it up. It is z26 and the tilt switch goes through pin 13 on the chip. It's 7404 in the bottom right corner next to J3.

I'm guessing if you remove that chip and put it in that $30 7400 chip tester, it will probably test bad.

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