Is the battery leaking on the CPU?

If you have no flashing lights on any of the boards then the A1 control board has not started.

While the battery may not have leaked (rarely does on Sys3), it may be dead. You can get around this by turning the machine on and pressing the reset button on the CPU board. If the LED does not blink after that, you could have a problem with the ROM, RAM, CPU, U6 watchdog or U11 74HC123.

Diagnosing and repairing control board faults on a Sys3 beyond swapping out socketed components is not something I would recommend as a starter repair project.

viperrwk

Lets keep it somewhat simple... What is your 5 volt reading on the cpu? Also, above the CPU is the display driverboard, look for U8, is it socketed?

Is it doing this?

That would be caused by the watchdog circuit going out of spec. Fixed on that Shaq via game ROM update.

The only thing you need working on this is your DMD board and your CPU board. Everything else can be taken out of the equation. You need a solid 5 volt going to them, and they both rely on each other to talk through the boot sequence. If your U8 is socketed, and your 5 volt is steady, replacing the U8 is an easy first step. Also, U8 is toast on a lot of these, and in many cases, it is caused by plugging/unplugging cables while the game was turned on.

Except for the pain of paying Steve Young $20 for it (Ed@GPE is out and isn't going to have new stock for a while.)

viperrwk

This could help some...

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_3

Before grabbing a new U8, remove power from the other boards, and leave only CPU and DMD driver board connected. Take your 5 volt down a bit to get it to sit right at the 5.0 mark (even though 5.2 should be fine, I have seen boards not boot with 5.2), the small center board has a dial on it to adjust the 5 volt. Once you have 5 volt and only those two boards connected, see if you get any boot. The red leds will alternate between the two boards while running. Also, once you are dialed in and only have these two connected, try hitting the reset button with the game on like viperwrk suggested to see if you get different results (you can try holding it for a few seconds too).

As far as U8 goes, that GAL chip is $20 at pbresource and like $5-ish at GPE, but it sounds like GPE might be out of stock (which happens quite a bit with this chip with them). Grab a socket to drop in U8 as well if you end up having to replace it.

if you have a part number digikey has parts as well.

They won't have the U8 GAL.... It is a custom programmed chip.

Thank you for keeping us updated with part replacement and what was fixed. Helps for future users having the same problem!

Tell us more about your scenario. Other boards hooked up? What are the lights on the boards doing? What does your display show, attract mode?

Awesome, glad you got it solved. Gladiators is a pretty fun game. I unplugged the shaker when I had it because it would try to walk the machine across the room, LOL...

Would one of you mind taking a pic of the inside of your cab? I don't remember what it looks like and where the shakers as. I picked one up tonight (it is at my friends house) and want to verify if it came with one.

Thanks! I want to say it's gone.... I'll know tomorrow