thanks dc42,
I am sure its possible, but I have to have decide this weekend, so I have no time to experiment .
I think I would have needed a double sided board for the normal MAX chip type multiplexing ? and the MAX chips here are over 10 times the price of the normal TPIC6B595N
I managed to design a single sided board with 5 TPICs for a 5x7 module today, and I know it works and I can get the chips. ( double sided boards are a lot more expensive here, especially the setup charges for a prototype board like this )
When I get a chance I will try some multiplex boards