So I have a very odd problem with my updated xenon. In the "test all lights flashing" it is very clear that all the LEDs turn on and fully off correctly. However, during game play the playfield lights are all partially on (really low level). Now when they are supposed to truly go on then they are bright on, and when off they are instead dim on. I have a new Altek MPU and lamp board in there so that's not it. Clearly there has to either be a floating ground or some low level voltage sitting on these LEDs that isn't enough to turn on a regular lamp. One other odd thing, when I am in display test mode (using LED updated score displays), and it is transitioning between1..2..3...on all displays, all the playfield lights briefly flash at each transition. Again this suggests some grounding or load issue to me when I've dealt with it in other electronics. Also I've seen sometimes that the leak current on the transitor in off state still enough to turn an LED partially on. But I would presume with the Altek board that this shouldn't be an issue.

Ah, thank you so much. Don't know how I missed that one.

Actually I do know how I missed this one. I realized that unlike the Altek MPU that the Lamp driver boards I've received from Marco and Cointaker don't actually come with instruction manual. I assumed it was just install and ready to go

So this isn't my particular issue as I screwed up on the Altek board install. However the basic concept (not trying to be pedantic if you likely already know this) is that all switch controlled transistors have a minimum leak current even when off. Normally for an incandescent bulb no problem as the leak current isnt enough to turn it on. Not so with an LED and thus it's possible they never quite turn completely off. When you are down in the barely activated range it will be barely visible and flicker. Usually from what I've seen it implies a floating ground. And from what I've seen of the Altek install that seems to be why they need an additional jumper wire installed when LEDs are installed. But I haven't gone thru their Circuitry to be sure