Onkyo TX-SA705 Service Manual page 151

OPERATION CHECK-4
Condition of Protect Mode
The unit will go into Protect mode under the following conditions.
(T: Thermal sensor temperature)
1. Thermal condition
After 10 minutes of T >= 100 C
or
Immediately T <= -30 C
or
Immediately T > 150 C
or
Immediately T >= 90 C (if T > 40 C when power is on)
or
Immediately T >= 90 C (if the unit is powered on longer than 24 hours)
2. DC voltage condition
The sum of dc voltage of 7 channnel speaker outputs is more than 7 V.
3. Current condition
Protect will be on if speaker output ac current >= 35 A.
Protect will not be on if speaker output ac current >= 11.7 A.
This condition is equivalent to OPERATION CHECK-2.
Test wave form:
Condition of Power Supply Control
The power supply voltage(VH or VL) for power amplifiers is changed by the relays: RL6901 and RL6902.
VH > VL (At VL, the maxmum speaker outputs are reduced for safety)
T: Thermal sensor temperature
VOLH: Pin #99 input voltage of Main microprocessor: Q2001 (Refer to SD-2:A3 and SD-5:G3 of Schematic Diagram.
VL: VOLH >= 0.45V and T >= 65 C
or
VOLH >= 2.6V (Longer than 240ms)
VH: Conditions except above
Condition of Cooling Fan Operation
The cooling fan will stop or rotate under the following conditions.
STOP:
VOLH < 0.35V
LOW SPEED:
VOLH >= 0.35V
MID SPEED:
VOLH > =0.55V or T >= 55 C
HIGH SPEED:
VOLH >= 0.45V and T >= 65 C
2 msec 2 msec
20 msec
TX-SR705/SA705
DSP output=max
(0dBFs)