Hello,

Gottlieb Mario Andretti with Sys 3 boards. All sound is out otherwise game is fine. Solid red on main sound board (actually it pulses at the normal rate but it is barely noticeable unless the room dark). Aux sound board has no LED. Removed aux board and hooked up separate 5v supply to the aux board and LED comes on. I did find a pin on the ribbon cable between the two was broken and looked like it had been previously repaired. Waiting for new cable. In the meantime my research seems to indicate the main board should "work", as in flashing LED, without the aux board attached and one of the most common failures is one, or both of the static ram chips on the main sound board (MA-1629). I'm trying to obtain a set of test ROM's loaded with MarAlb's test code. I don't have a way to burn the ROM's so I'm trying to find someone who can supply me with a set of test ROM's already burned. I'm located in northeast Ohio.

Greg

Group. Just to let you know. Thanks to latenite04's help it does appear my Y ram is bad. I got the test roms and upon initial power up I get in sync blinking board and test rom led's when on the Y side CPU. I push the reset button and board LED goes out, get 1 bright flash on test LED then it goes to a steady dim and that's it. Moving to the D side CPU, same on power up. Pushing the reset button OR briefly grounding pin 6 on the D side 6502 CPU cause board LED to go out but the test LED does exactly what Marco's manual says it should do. It does a bright flash, dim flash, bright flash, pause and then goes into what Marco calls idling mode (steady but slow flashing). This happens over only a very few seconds.

Now if I have the courage to try and replace the y-ram. Last time I worked on the driver board for this machine (years ago), it didn't go well trying to replace some blown mosfet's on the board. Got it done but not pretty. I seem to remember trying to get the blown chips out in one piece, bad move, I know better now and cut legs.

Greg

Took the plunge. All went well. Bought a manual heated solder sucker, best purchase ever for this type of work. Ended up installing 2 rows of SIP sockets instead of one DIP socket. Verified continuity on all pins. Hooked it up and all sounds back. Thanks for all the help.
Greg