At this stage, I'm not sure, I'll have to sleep on it, quite possibly I will have to re do both tlc5940 controller boards, make them better, use better wire for the connections perhaps..
You can't really make it out very well but in the below, ten LEDs are supposed to be lit and the rest not, the ones which are lit but dim are actually flickering, which you obviously can't see in the photo.
This is the traces of 2 of the 8 layer select MOSFETS doing their thing. I was happy to see this, it looks pretty good. You can see the high segment on the bottom trace followed by the high segment on the top trace, this is where the mosfets are "ON". The remaining 6 mosfets would fill the rest of the gaps where the small bumps are, but the CRO only has 2 probes.
This is interesting, i took measurements of what comes out of the TLC5940 output at various intensity levels. This 1st photo shows 2 traces, the bottom is at full brightness, the tlc5940 has 12 bit brightness so that equals to 4095. The top trace is at 3000, so you can see roughly a quarter is high and the remainder is low. Of course the tlc is a current sink so low is actually ON.
Similar thing with 2000 brightness on the bottom trace and 1000 brightness on the top trace. Nice to see PWM in action.