hatmoose
Enlightened
Once again huge thanks to Ack (now on Arcade Projects yaaaaay!) for keeping the art of NeoGeo repair alive. I've been learning for some time now - was determined to get this one done myself - but have had to give up and ask for help.
Had glitches overlaid on the screen, eventually traced to stuck bits 6 and 7 being generated by a bad NEO-IO
Changed the NEO-IO for a known good one which did not work, then worked once when I pushed hard on the NEO-IO
http://www.neo-geo.com/forums/index...arbage-overlaid-on-screen.269092/post-4440829
Then has never worked again
With unibios its a fast watchdog
With testbios it boots to garbled graphics like watchdog but then sticks there
So the two most likely possibilities are
1) I damaged some of the pads/traces when I was swapping the NEO-IO
2) I damaged the NEO-IO when I was swapping it over
3) something else entirely
I've used my new HP10525T logic probe to poke all the pins, and I also have a known good MV4FT to compare with.
Weirdness from the logic probe is as follows
PIN 19 ORI0 (OR input #0)
On the known good board this is slow pulse, on the bad board its LOW
PIN 20 ORI1 (OR input #1)
On the known good board this is PULSE, on the bad board its PULSE
PIN 21 ORO0 (OR output)
On the known good board this is PULSE, on the bad board its PULSE
PIN29 ROMOE
On the known good board this is slow pulse, on the bad board its HIGH
PIN30 ROMOEU
On the known good board this is slow pulse, on the bad board its HIGH
PIN31 ROMOEL
On the known good board this is slow pulse, on the bad board its HIGH
So if I cooked the chip that would explain it. But before I find another donor chip I want to check that it's not just a bad trace.
Unfortunately I'm having trouble reading the pinout for the NEO-IO here
https://wiki.neogeodev.org/index.php?title=NEO-I0
I can't figure out where Pin 19 ORI0 is coming from, so I can't check continuity from the source
I can't figure out where Pin 31 and Pin 30 ROMOEL and ROMOEU are coming from so I can't check continuity from those sources
I can't figure out where Pin 29 ROMOE goes so I can't check it's being sent to so I can't check continuity to that destination.
Any thoughts on how I can find the inputs and outputs for those pins would be hugely appreciated.
Had glitches overlaid on the screen, eventually traced to stuck bits 6 and 7 being generated by a bad NEO-IO
Changed the NEO-IO for a known good one which did not work, then worked once when I pushed hard on the NEO-IO
http://www.neo-geo.com/forums/index...arbage-overlaid-on-screen.269092/post-4440829
Then has never worked again
With unibios its a fast watchdog
With testbios it boots to garbled graphics like watchdog but then sticks there
So the two most likely possibilities are
1) I damaged some of the pads/traces when I was swapping the NEO-IO
2) I damaged the NEO-IO when I was swapping it over
3) something else entirely
I've used my new HP10525T logic probe to poke all the pins, and I also have a known good MV4FT to compare with.
Weirdness from the logic probe is as follows
PIN 19 ORI0 (OR input #0)
On the known good board this is slow pulse, on the bad board its LOW
PIN 20 ORI1 (OR input #1)
On the known good board this is PULSE, on the bad board its PULSE
PIN 21 ORO0 (OR output)
On the known good board this is PULSE, on the bad board its PULSE
PIN29 ROMOE
On the known good board this is slow pulse, on the bad board its HIGH
PIN30 ROMOEU
On the known good board this is slow pulse, on the bad board its HIGH
PIN31 ROMOEL
On the known good board this is slow pulse, on the bad board its HIGH
So if I cooked the chip that would explain it. But before I find another donor chip I want to check that it's not just a bad trace.
Unfortunately I'm having trouble reading the pinout for the NEO-IO here
https://wiki.neogeodev.org/index.php?title=NEO-I0
I can't figure out where Pin 19 ORI0 is coming from, so I can't check continuity from the source
I can't figure out where Pin 31 and Pin 30 ROMOEL and ROMOEU are coming from so I can't check continuity from those sources
I can't figure out where Pin 29 ROMOE goes so I can't check it's being sent to so I can't check continuity to that destination.
Any thoughts on how I can find the inputs and outputs for those pins would be hugely appreciated.
