WMS Jackpot Stampede Deluxe - not playing after startup

[pathfinder2072]

Hello.  New to this forum and slots in general.  Great site btw.
I recently picked up a Williams Jackpot Stampede Deluxe and have the following scenario:1-Unit powers on2-Does a ROM check3-Displays Williams logo for about one minute, then dot screen goes blank.
A) No "bong" at startup (although, there might be no sound at all)B) No fail light on I/O board, but only far left and far right LED's are litC) There appears to be no power to coin, Bill, Hopper, front buttons, lower lcd displays or reels
I don't seem to be missing any boards, but cannot be certain
Steps Taken so far:1) cleaned and verified seating of all connectors and IC chips2) found weakness in upper power supply so did the ATX replacement (great procedure, made it easy)
I do have some experience with arcade coin ops, but this has me stumped.
Any help/guidance would be appreciated.
Thanks!

[Sunrise Side]

I believe your lower power supply is bad.  You can do the same  ATX conversion to the lower PS. There's details for that as well.

[pathfinder2072]

Thanks!  I will give that a try.

[pathfinder2072]

Completed the ATX procedure.

Works now all the way.
Thanks!