PROTECTION CICUIT-
SUP. 6
REG DET input:
(for models RX-D401/402/701/702)
This input detects the regulated voltages: A+5V_Vi,
A+5V_DSP, +9V_Vi_Tu, +7V, D+5V(DSP), and
d+5v(HDMI). If any of these six voltages are
missing, it may cause one of six transistors
(Q162, Q163, Q161, Q505, Q506 and Q507) to turn
off and to give a LOW state input at pin 28 of IC501.