Neo Geo MV2F crosshatch of death: is this a broken NEO-E0?

mourix

n00b
Joined
Feb 22, 2016
Posts
28
I am trying to repair an MV2F board that won't load any game. It boots straight to the crosshatch test. The unibios memory viewer recognizes activity on the slots, but it will not boot anything.

I probed Prog slot pin B5-B23 which should be the A-bus for PROM1. It showed activity at all pins except for A3 which was stuck high.

Pin A3 beeps out to NEO-E0 pin 7, which is still stuck high. According to here, pin 7 is the buffered output of Pin 2. Pin 2 does show activity.

Am I correctly assuming this NEO-E0 is dead? Or am I reading it all wrong. See the attached pictures for my workflow. Advice would be nice.
 

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mourix

n00b
Joined
Feb 22, 2016
Posts
28
Update

I got a replacement NEO-E0 off ebay and replacing the chip got pin 7 alive.

The games booted up with vertical lines in both slots. This turned out to be a corroded trace between a NEO-257 and ZMC2.

One patch wire and backup batter mod later, and I'm the proud owner of a playable board WITHOUT SOUND.

Well, time to get out the scope again ;)
 

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