04-12-2013, 10:30 PM
The easy thing to do would be to take a 4.7M resistor and run it between either end (unless you can locate which end should connect to R506) of R507 to ground and see if it makes a difference on you AVC. As noted above, one end of R507 should read ~4.7M and the other should read ~9.4M to ground. These will of course vary some due to value drift of the resistors.