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Museum of the Game® & International Arcade Museum® Forums
I picked up a battlezone that needs some work. It sat abandoned for a while and ended up in my possession. I'm trying to tackle this project but I am not very familiar with this boardset so I am hoping to get some insight. Things I have done and verified:
AR2 is working, had a bit of a headache for a moment because 2N3055s do what they do but all output voltages are fine now
Big blue had to be replaced, tested bad.
I burned a new romset - Legs were rusting away on the old ones and some legs even crumbled nicely
New CPU - same deal as the rom legs
Cold solder joints between the main board and aux board were addressed
Made a new interconnect cable for the two boards
I normally don't like just replacing chips like the roms without at least verifying but I didn't have much of a choice. So what is going on with this thing? Well right now not a whole lot. The reset pin is not toggling on the 6502. When adding a jumper wire into the test mode, it isn't beeping or anything like that. The engine rumbling sound is constantly playing. Looking at the XY outputs using my scope, it isn't doing much other than a slanted line. Looking at the vector roms, neither ROM get enabled. I saw that the ROM select utilizes the decoder at C4, it never actually uses VROM2/3 because AM12 is stuck. Tracing back I see that E5 isn't counting for one reason or another. It gets it's clock from F5 but I haven't hooked up the logic analyzer yet to see if it actually counts correctly. This is a far back as I went with this since I didn't pull out the logic analyzer. There is activity on VRAM but the DVG0 - DVG3 bus is stuck low. I'm not sure what the deal is with that but I can imagine that *probably* isn't right. I'm a bit confused as to why it's only the lower end, perhaps something in the Vector Generator data shifter has failed and is pulling that bus low?
Really, I am looking for some guidance on how to tackle this. I don't fully understand the vector generator stuff and would like to learn a bit more by troubleshooting this. Any input is appreciated. Sometime today or tomorrow I am gonna try to hook up the fluke to make sure it can actually see the program correctly and the lack of a watchdog isn't lying to me.