Hi. First grab the v2 schematic code.google.com/p/dsonano/downlo … Scheme.pdf
And datasheet pdf1.alldatasheet.com/datasheet- … HC125.html
What board version of V2 do you have?
You should forget about R25, R26. These are related to USB not Func Generator.
Lets make sure your 74HC125 has VCC on pin 14. Should be close to Battery voltage. Mine has 3.7v
And pin 8 about half of Battery voltage. Mine has 1.9v.
Attached pics of my Nano 2.5. I placed Ground Volt meter probe on USB shield and Red to VCC of 74HC125 pin 14 then 8.
Be careful.
