Xmultiply M72 not booting

[futasan]

Hello

Need help to fix Irem M72 Xmultiply pcb.
The game at power up is stuck on a solid white screen.
Swapping layers pointed the main (middle) board to be the problem.
Started probing the main cpu (nec v30), reset line is low (active high on this one) so it’s ok.
CLK seems ok also.
What should I check next to further investigate?

 

[Darksoft]

do you have proper and continuous data on the DATA and ADDRESS lines? Are eproms OK and with the right content?

 

[Apocalypse]

It's always very difficult to remotely guide people in their repairs.
Having a reset signal at the expected level isn't enough. There must be a long enough active state on power up before it goes inactive.
Also was the board working when you got it?
Can be really anything with the symptoms you describe but I'd check work RAMs first.

 

[Darksoft]

Well, If you can't/don't want to fix it, let me know your price. I'm eagerly looking for one.

 

[futasan]

Thanks for your replies.
I’ve been very busy with work and don’t had time for this repair until this week-end.
Long story short, reset line and clk was ok. Probing on the V30 I found some data lines stuck low and fixed it (don’t have the ic reference and placement atm). No change on the boot but data lines are ok.
Finally checked and found poor connection on pals @ic11 and 19. Swapping the socket fixed the boot issue.
Fixed the bottom board by changing ic1, customs @ic3 and ic9 (faulty ic9 made the screen noisy, colors washed out and the board to reboot in loop).
Now remains graphical issue (x-multiply spinning logo for ex.) to fix, top and bottom boards are ok.
Once I finish this repair i’ll try to make a repairlog.