Power the machine on. If it doesn't boot press the reset button on the CPU board. If it boots after that check the on-board battery voltage (probably low). If it still doesn't boot reseat/replace the cable between the driver board and CPU board.

If you're going to shotgun the board, do C20 and C21 before trying U11.

I don't remember your troubleshooting with the display itself. Have you tried a different one in CBW? The GAL either works or it doesn't.

viperrwk

a display that is starting to outgas and not work in a B/W game, will work in a gottlieb, since gottlieb using a lot lower voltage to run the display. so if its' burnt out on a gottlieb it's really burnt out.

just a note. Never unplug a dmd while the game is on for a gottlieb. You will blow the GAL chip instantly. They don't like that. You can unplug the ribbon on anything else without problems, just not gottlieb. only the ribbon tho.

You can try the DE DMD you have - shouldn't be a problem.

Try reseating the ribbon cable. You may also want to just get a couple of new ones. Same cable from the CPU to the DMD/driver board - they are interchangable.

The other thing you can try is disconnect EVERYTHING from the DMD controller and disconnect the ribbons to the CPU board and then power it on and see if the LED starts blinking on power up. If it does then something connected to the CPU board is keeping it from booting. If it doesn't and you have to try your power trick, then the problem is on the CPU board. You may want to try a new ROM to see if perhaps it is suffering from bit rot. An EPROM I tested recently was giving me different results every time I went to verify it. On rare occasion it would yield the correct checksum but in no way was it consistent. It needed to be erased and reburned.

Unfortunately, by this point, there's not much else you can do unless you start shotgunning. And this is not a board to shotgun. Sys3 has some very fine traces and it is super easy to damage the board if you're not careful.

If you do decide to go this route, start with the caps as I mentioned earlier. If that doesn't work, then a new U11 would be next. And if that isn't it then a new RAM. But you see where this is going...

viperrwk

K's or Clive at Coin-Op Cauldron.

Consider this: by the time you pay shipping and repair to Clive you'll be out $110. A new CPU board from Steve Young shipped to you is $130. And you should be able to sell your non-working board for at least $20.

viperrwk

backwards. An outgassing display needs more voltage to get it to light. A borderline but fully working display in a B/W game probably won't light in a gottlieb that has a lower voltage power supply.

My experience with booting issues on gottlieb system 3's has always been the U11 chip. It must be a 74hc123 chip and not an LS version. Something about the timing of the reset going out as the chip ages. Most of the time when this is bad the game won't boot and will be stuck in a reset loop (repeated chirping of the sound) If you roll up the voltage a touch using the trim pot on the 5V power supply and the game boots then it's definitely the U11 chip.

Now on system 3-11 Williams MPU boards there is a 22 uf cap in the reset section that when bad will cause this exact problem, it won't boot unless you do a quick double flip of the switch. I have never seen it happen exactly this way on a Gottlieb but I am guessing that the 1 uf caps at C20 and C21 that viperrwk mentions are the equivalent.

yes, that's what I ment. I was thinking it in my head when typing and came out completely backwards to what I ment to say. My bad. More voltage means more ummph to kick it in high gear.

C20 and C21 are more likely to go out with age than U11.

Additionally, Gottlieb changed the values on R5 and R6 which (if CBW has its original CPU board), was 330K to 680K in later CPUs which reduces the sensitivity in the watchdog circuit. If I was shotgunning the board I would change C20, C21, R5 and R6 before changing U11.

viperrwk

You sure need that ramp shot
Hit that ramp
What kinda cowpie shot was that
By golly thats an extra ball.
You got the special!
Yeee. Haaaa. Whata shot.

I played the hell out of a cbw back in college in the mid 90s. I have those callouts and that theme buried deep in my head.