Arduino with TLC5940

I am trying to do this with 2 x TLC5940 and an arduino uno.

The circuit is simple enough and I am certain I have it correct.

I have modified NUM_TLCS in the TLC5940 config file.

And I have three LEDs hooked up to the first 3 channels at present.

But it just wont work - I get nothing with the basic usage example in the TLC5940 library.

Any hints as to what I might have done wrong?

I did get a breif flash out of the LEDs while I was swapping connecting wire around on the arduino uno. But it does not work with thing wired up as per this diagram:

Has this been a change in the library perhaps that renders this wiring diagram invalid?

Any hints as to what I might have done wrong?

Yes you believe this:-

the circuit is simple enough and I am certain I have it correct.

Has this been a change in the library perhaps that renders this wiring diagram invalid?

Could be but with the scant information given who knows.

I did get a breif flash out of the LEDs while I was swapping connecting wire around on the arduino uno.

Never ever rewire things with the power on. That is the quickest way to destroy electronic circuits.

Please read this:-
How to use this forum
And see how to ask a question here.

Also that schematic has no decoupling capacitors on it, so the person who wrote it knows very little about electronics.
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

boylesg:
I have modified NUM_TLCS in the TLC5940 config file.

Try putting the config file back the way it was and use #define NUM_TLCS 2
I think there might be more than one place you need to change the number and that would do all of them at once. If that doesn't work, did you remember to delete Tlc.5940.o so that changes will be applied?

If that doesn't work, did you remember to delete Tlc.5940.o so that changes will be applied?

No that was only with versions of the IDE less than 1.0.0. With the IDE that has been in place for the last four years the .o files are created on every compile, there is no need to delete them.