Sega 16b running Shinobi set 3 no sound. Already Replaced A7 eprom and Z80b.

[aapuzzo]

This board wasn't booting but I was able to resolve that issue. I thought it would be as simple as replacing the encrypted chip with a z80b and replacing the A7 eprom but no dice. I do ear a small hum that gets louder or quieter if I turn the volume pot.

Z80b
6 clock = pulsing
16 INT = L
17 NMI = H
18 halt = no signal
21 RD = H
22 WR = H
24 Wait = H
23 BUSACK = dead
25 BUSRQ = H
26 Reset = goes from low to high a few seconds after power up


I can check any other pins or chips as need or probe all other z80b pins. Other than the clock none of the pins are pulsing. Many of the address pins are dead.


Any ideas?

 

[aapuzzo]

To anybody that ever stumbles upon this thread I fixed this problem. Apparently my stupid replacement Zirlog z80bs I bought from ebay aren't microprocessors. Image below. I guess they need to say CPU on them and not all z80bs say "z80b" on them. They have a part number on them like Z84C0006PEC where the 6 means the MHz and is the b variant.