I also promised a bit of feedback on the display issues.
After a long an extensive troubleshooting, including mailing the good guys at PinballControllers I finally found the answer - a broken cable.
After numerous testing, pulling and inserting the old rudimentary cable must have snapped internally and just barely worked. This probably means the logic level converter would have worked - although it's entirely redundant now so it won't be reconnected.
After making the new, better and final display cable it looks really good!
|2) The old display for comparison. Note the uneven brightness of the LED modules and the clearly visible grid of modules. This is NOT a great display.|
Another nice thing about this display is the unique power protection that keeps the columns blank during the upstart, and starts the display when it find the row scanning. That means, the display is blank when booting and turns off automatically in case the host fails and thus no burnt display.
Too bad I had to experience the bad display before I found the good one. To make it worse, they were almost in the same price range but I chose the cheaper. Shame on me.
Just a side note -
If you're like me and is creating or is planning to create your own pinball machine, check out PinballControllers. They got great hardware for doing custom machines and a very mature code library (believe me, I've wrestled quite a bit of code - and not everyone likes their bits and bytes!) that really boost development. Their customer support is extremely helpful as well!
Had I known about it when I started my machine I would have cut the development time in half.