The official Behringer website provides a user manual for the Xenyx QX1202USB, but the service manual is not readily available for public download.
: For non-internal parts (like the specialized 3-pin AC power adapter), consult authorized retailers as the mixer cannot be powered via USB. Are you experiencing a specific hardware issue or just looking for the wiring diagrams XENYX QX1202USB/QX1002USB behringer xenyx qx1202usb service manual
Behringer, unlike many modern manufacturers, still releases these documents (often through third-party archives and MidiMan support repositories). For the QX1202USB, the manual is roughly 15–20 pages of dense, invaluable information. The official Behringer website provides a user manual