Hi,
All sorted…
Latched down j6/7 & neglected to remember that the chip has its own onboard DAC/AIN section..
Many hours of trouble shooting the ain boards pointed the problem down to some incomplete pcb traces on some diy boards made with a friends etching kit …and afew chips which came out of the surplus pile & where not tested properly..
A Quick Errata & some check points that sprang to mind:
afew symptoms encountered with interface debugging..
1: Random AIN data during testing as above; was due to neglecting to earth the PIC chips own AIN section; as provided by J7.
Linking all the pins togeather on J7; -EXCEPT- the 2nd pin (vd/+5v) (as viewed when the notch on the pic is at the ‘top’).
2: Random DIN data transmitted when a ‘switch’ is pressed… most likely cause is faulty chip; change & see what happens - otherwise check soldering & conncetions around linked chip.
3: No button presses received.. Check connections & soldering; however if it occurs along an DIN board chain whereby some chips are working ok; but the last one is exhibiting symptoms as seen in ‘2’ ..then this chip is stopping any good singlas working their way down the line.
4: Lights Driven by DOUT board behave erratically/ flicker.. as always.. check connections.
However also note that it is vital for reliable opperation - that some capacitors are added onto the power supply rail of the board. use one 47-470uf on the main input & as mentioned in the AIN construction article at ucapps.de a 100nf cap by each chip ideally.
5: Two or more buttons trigger the same number on testing…
usually just two connection points that are soldered togeather/ touching. Though watch out for any small loose touching wire filaments or tiny splashes at the base of the connection points, which can easily esape detection.
6: constant random signals / afew connections on a DIN board not triggering…
Pay particular attention to Resistor (& chip socket) soldering… though all else fails.. try new chip.
7: Some LED’s are brighter or dimmer than others.
Check how much current your leds can handle (10-30ma is the typical range). and either work out safe resistances with abit of math.. or go for trial and error.. replacing the resistor that drives each concerned led with a larger resistance for less brigtness …and when decreasing the resistor value to gain brightness; be sure to place a multimeter in series with the LED and make sure that the resistance value used does not exceed the LED’s max specifyed current (otherwise it’ll change colour (often!) & burn out really quick)
8: make sure that whatever you are using to power everything (ie the measily 1amp reg & diode bridge on the cpu board) are sutibly upgraded (or other supply built into case) to handle all the power used to drive everything. 1 amp regs & connected in parallel to add up the current handling.. however note that for more than 500ma current handling and they get very hot. they need to be bolted to a metal surface to take the heat away.. usually the case is best. however if it is steel; make sure to use a small sliver of aluminum behind the regs to hlp spread the heat out better. Always use heatsink paste to improve thermal conoductivity.
8b: Make sure that whatever ultimately powers the box (wall wart power pack or transformer); that it can provide the regulation circuit with the power it needs too ! 
…ie a 3.7v 350ma phone charger will not power a regulator circuit that needs 11-20v (12v usually best) at around 800 ma / 0.8 amps.
9: Most problems are bad connections / missed wiring or components..