I picked up a newer faulty neo-mvh slot4f with the smd's on the top board about a year ago, had graphics faults and some funky audio.
I managed to trace find some corroded traces on the bottom board, next on the LSPC2 I reflowed some solder and repaired 2 pins that broke off in the process, and that fixed graphics on all slots.
Now i drew my attention to the sound side and replaced every cap, Ym2610, Ym3016, amp, headphone slider and some 74ls245s. I probably replaced some other stuff too...
At this point slot 3 and 4 are working flawlessly but 1 and 2 still have audio problems, music and the neo geo intro are fine but sound effects are distorted.
I have checked alot of the traces on the top board but im beginning to think one of the infamous smds on the top board aren't working correctly.
if anyone knows what cart pins control the sound effects that could help me narrow it down, i also have a logic probe but i dont know how to use it..
Another thing to note is a did a z80 diagnostic test and cart 1,3 and 4 came up with nothing, but cart 2 came up with a z80 m1 upper address error. but only once or twice after multiple tests.
any help would be appreciated, cheers vaughan.
I managed to trace find some corroded traces on the bottom board, next on the LSPC2 I reflowed some solder and repaired 2 pins that broke off in the process, and that fixed graphics on all slots.
Now i drew my attention to the sound side and replaced every cap, Ym2610, Ym3016, amp, headphone slider and some 74ls245s. I probably replaced some other stuff too...
At this point slot 3 and 4 are working flawlessly but 1 and 2 still have audio problems, music and the neo geo intro are fine but sound effects are distorted.
I have checked alot of the traces on the top board but im beginning to think one of the infamous smds on the top board aren't working correctly.
if anyone knows what cart pins control the sound effects that could help me narrow it down, i also have a logic probe but i dont know how to use it..
Another thing to note is a did a z80 diagnostic test and cart 1,3 and 4 came up with nothing, but cart 2 came up with a z80 m1 upper address error. but only once or twice after multiple tests.
any help would be appreciated, cheers vaughan.