Pioneer VSX-808RDS IR problems (Was: Testing an I.R. Receiver)

[Old Sparky]

I have now checked the connections on the board containing the IR in & Out Sockets. Everything checks out OK, no sign of dry joints, etc. Ribbon cable are in good conditon and, as far as I checked this afternoon, making good contact in their sockets. One thing I've generally nver known how to 'cold check' are those transistors with built-in resistors, at least one of which is used in this circuit. Obviously checking such a device with the diode test range on a DMM doesn't work, so the only way I know is to take voltage readings with the device powered.