Pulse Power Supply - Power On/Audio Unmute - Sony XM-1502SX Training Manual

The car amplifier stages are listed in Table 1-2. The operational inputs and outputs are also listed.
Stage
Power ON
DC-DC Conv
Audio
Process
Protection
Circuit 1
Protection
Circuit 2
Thermistors
Balance
Detector
Pulse Power Supply - Power ON / Audio Unmute
Refer to Figure 1-3. Although +12V car battery power may be applied to the power amplifier, the unit will not
power ON until the REM input is applied at least 7.4Vdc. At that time, the battery +12Vdc is switched into the DC-
DC Converter stage that makes all the voltages for the power amplifier and the unit powers ON. At power ON the
audio amplifier is un-muted and both channels can operate.
Table 1-1 - Amplifier Stages (refer to Figure 1-2)
Major Parts Constant Inputs
Q901-3 Battery +12V
IC901, Pin 1 = 0V (Protect
T901, Q910, Latch 1&2).
Q911.
Pin 4 = 0.6V
(Regulation input)
Pin 16 = 0.2V
(Thermistor input)
See Fig. 1-3 Left only or left &
right channel audio.
Q810-811 DC-DC Converter
(not shown) voltage
Q812-813 DC-DC Converter
(not shown) voltage
Thermistors DC-DC Converter
voltage
Q912 +20V
Switched Inputs
REM (7.4V min)
+12V
Audio Unmute
@ power ON
Offset of
speaker output
voltage
Excessive
speaker current
High case
temperature
Unbalanced
+20V
supply/load
4
1. Car Power Amplifier
Output(s)
(Switched) +12V
+50Vdc
+14.2Vdc
+20Vdc
Audio to
speaker(s)
Loss of DC-DC
Conv Output
Loss of DC-DC
Conv Output
Loss of DC-DC
Conv Output
Loss of DC-DC
Conv Output