Sony XM-1502SX - Stereo Power Amplifier Installation guide

Training Manual
Course: A-125
Car Amp & Video,
& Music Storage Units
Models: XM-1502SX XM-475GSX
XM-2150GSX XM-1902SX
DRN-XM01 XM-5150GSX
XT-XM1
XAV-7W
XVM-R75
MEX-5Di
MEX-1HD
Circuit Descriptions & Troubleshooting
XM-2150GSX
XVM-R75
MEX-5Di

Table of Contents
CourseA-125-CarAmp&Video,
&MusicStorageUnits
Introduction............................................................ 1
1.CarPowerAmplifier .........................2
Circuit Block Concept/Overview......................... 3
Pulse Power Supply -
Power ON/Audio Unmute .................................... 4
Audio Processing - Input Stages ........................ 8
Protection Circuit - PS Oscillator
Stop 1 (Thermal) .................................................. 12
Protection Circuit - Oscillator
Stop 2 (Offset) ...................................................... 14
Protection Circuit - Oscillator
Stop 3 (Current).................................................... 15
2. Satellite Radio ..................................17
XM vs. Sirius Radio ............................................. 17
System Operation................................................ 17
XM Radio Components....................................... 18
Activation............................................................... 18
3. Display Products ..............................19
XAV-7W - Operation............................................ 19
XAV-7W - Access................................................. 20
XAV-7W - Motor/Power ON Circuitry................ 23
XAV-7W - Display ................................................ 24
XAV-7W - Backlight Operation........................... 24
XVM-R75 - Video Monitor Operation................ 27
XVM-R75 - Powering the Backlight................... 29
MEX-5Di - Operation and Power ON................ 30
MEX-5Di - Backlight ............................................ 32
4.Car Music Storage Unit...................34
Playback................................................................ 34
Recording .............................................................. 36
Recording from CD (into the HDD)................... 37
Checking out Songs from the Hard Drive
into the Memory Stick.......................................... 39
Checking back IN the Music from the
MG Memory Stick to the HDD............................ 40
CD Circuitry........................................................... 42
Hard Drive Circuitry ............................................. 47
AM / FM / Aux Circuitry ....................................... 49
Memory Stick Circuitry ........................................ 50
Display Circuitry ................................................... 51
AppendixA -Music Handling .............. i
Electronic Music Distribution (EMD)...................i
Secure Digital Music Initiative (SDMI) ................i
MagicGate ...............................................................i
OpenMG Jukebox Software.................................i
AppendixB - LCD................................. iii
LCD Concept.........................................................iii
LCD Operation ......................................................iii
Appendix C - CD-4 & CD-RW ...............v
CD-R ........................................................................v
CD-RW ....................................................................v
Problems .................................................................v
Disc Comparisons.................................................vi

1
1. DA-4 & DA-4X PCB Interconnection
Course A-125
Car Amp & Video, & Music Storage Units
Introduction
This booklet is divided into four chapters covering the following:
1. Car Power Amplifiers – Sample model XM1502SX / XM2150GSX (very similar to XM5150GSX, XM-1902SX
and XM475GSX).
2. Satellite Radio – The third radio band sample model DRN-XM01, XT-XM1
3. Video Display Unit – Sample unit models XVA-7W, XVM-R75, MEX5Di
4. Music Storage Unit – Sample unit model MEX-1HD
Operation, Concept, Hookup and Troubleshooting are provided for the products listed above except for the
Satellite radio. There is no circuit troubleshooting for the Satellite radio in this booklet.

2
1. Car Power Amplifier
R
(STEREO)
+
-L. AMP. -
+
-
+R. AMP.
(INVERT.) -
+
+
C131
220
16V
R154
4.7k
C221
0.1 R254
1k
-
-
+
+
-
LHOT
HOT
MONO STEREO
150W@
0.04% THD
380W@
0.1% THD
INPUT
FIGURE 1-1 - FLEXIBLE INPUT CONFIGURATION 12A125 1487 11/11/02
+
+
-
BATT. DC
INPUT
PL801
30 OHM
AMP.METAL
CASE C804
0.1
R811 2.2k
C101
C102
C201
C202
MONO 4Ω
4Ω
4Ω
Chapter 1 - Car Power Amplifier
This power amplifier section is divided into the following parts:
•Hookup
•Circuit Block Concept / Overview
•Pulse Power Supply – Power ON / Audio Unmute
•Pulse Power Supply – Oscillator / Output
•Pulse Power Supply – Testing
•Audio Processing – Input Stages
•Audio Processing – Output Operation
•Audio Processing – Output Troubleshooting
•Protection Circuit – Oscillator Stop 1 (Thermal)
•Protection Circuit – Oscillator Stop 2 (Offset)
•Protection Circuit – Oscillator Stop 3 (Current)
Hookup
Single Speaker – Mono or Center
Mono - By changing the audio input, output and ground configuration, the stereo power amp can alternately be
used in a bridged monaural configuration for more power as shown in Figure 1-1. Only the left input jack is used
in monaural.

3
1. Car Power Amplifier
ON/OFF
REM
L
RAUDIO PROCESS
Q901-
903
POWER
ON IC901
DC-DC
CONV.
8
8
1
9
4
16 3
10
THERMISTORS
PROTECT
LATCH 1, 2
T901
Q904-
907
REGULATION
Q912
L
R
Q910,
Q911 REG.
BATT.
+12V
TO
SPEAKERS
+
-50V
+
-14.2V
0.6V
LATCH
0V
0.2V
POWER
LED
MUTE SW
+12V
OSC.
OUT
+20V
THERMO
LED
LEDS:
OFFSET
SPEAKER
CURRENT
-20V
OSC.STOP
0V
36.4kHz 10Vp-p
FIGURE 1-2 - POWER AMP. BLOCK (XM1502/2150) 14A125 1490 11/14/02
Center - If both left and right inputs were used with a single speaker output, the sounds common to both channels
are doubled to the speaker, making this configuration useful as a center channel. Center channel operation is
possible because of two signal inversions. The inverted right channel is applied to the bottom end of the speaker.
The combined effect is two audio inversions or reinforcement of signal common to both channels.
Ground Connections – Audio, Power and Case
Refer to Figure 1-1. The audio and power grounds are kept separate in this unit (R811 = 2.2k ohms) to prevent
alternator and power noise from getting into the audio. For repair purposes, the two grounds (audio and power)
can be connected together for testing, but the connection must be made when there is no audio output to
prevent a sudden surge path.
Theamplifier’s case is connected to the power ground via a 30-ohm lamp. The lamp’s low DC resistance places
the metal case at ground potential yet prevents a voltage applied to the mounted case from blowing the fuse and
disabling the amplifier. An inadvertently applied voltage at the case would just light the lamp.
Power Output – Stereo vs. Mono
The RMS power output is 150 watts at 0.04% THD / per channel (stereo). In monaural where both channels are
applied to a single speaker (bridged), the power is doubled to 300 watts. If a bit more distortion is accepted, the
same output can be rated at 380 watts at 0.1 THD.
CircuitBlockConcept/Overview
Refer to Figure 1-2. Modern high power car power amplifiers contain:
•Pulse power supply to deliver ground isolated multiple operating voltages.
•Audio processing stage for the left and right channel amplification.
•Protection (latch) circuitry. The protection circuit will shut off the pulse power supply and hold it off if:
1. The amplifier gets too hot (thermistors);
2. If the speakers draw too much current (latch 1); or
3. The signal is unsymmetrical (latch 2).

4
1. Car Power Amplifier
The car amplifier stages are listed in Table 1-2. The operational inputs and outputs are also listed.
Table 1-1 -Amplifier Stages (refer to Figure 1-2)
Stage Major Parts Constant Inputs Switched Inputs Output(s)
Power ON Q901-3Battery +12V REM (7.4V min) (Switched) +12V
DC-DC Conv IC901,
T901, Q910,
Q911.
Pin 1 = 0V (Protect
Latch 1&2).
Pin 4 = 0.6V
(Regulation input)
Pin 16 = 0.2V
(Thermistor input)
+12V +50Vdc
+14.2Vdc
+20Vdc
Audio
Process See Fig. 1-3Left only or left & right channel audio. Audio Unmute @ power ON Audio to speaker(s)
Protection
Circuit 1 Q810-811 (not shown) DC-DC Converter voltage Offset of speaker output
voltage
Loss of DC-DC
Conv Output
Protection
Circuit 2 Q812-813 (not shown) DC-DC Converter voltage Excessive speaker current Loss of DC-DC Conv Output
Thermistors Thermistors DC-DC Converter
voltage High case temperature Loss of DC-DC Conv Output
Balance
Detector Q912 +20V Unbalanced +20V
supply/load
Loss of DC-DC
Conv Output
PulsePower Supply - Power ON/AudioUnmute
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.

5
1. Car Power Amplifier
IC101-IC104
PREAMP./FILTER
L
IC201-IC204
PREAMP./FILTER
R
Q103-Q113
OUTPUT STAGE
L
Q203-Q213
OUTPUT STAGE R
R229
R801 1M
20V
+
-
L
RR129
1
2
3
4
Q102
Q202
Q102,Q202 LINE SW.
LEFT
OUTPUT
RIGHT
OUTPUT
20V
14.2V
R804
100k
R805
D802
D801
6.8V
Q802
Q801 R802
IC902
SWITCHED
+12V
TO DC-DC
CONV. IC901
IC902
GROUND
ISOLATION
-14.2V
+12V
BATTERY
REM
C913
0.001
R909
R928
100k
R911
100k
POWER
ON
(7.4V MIN.)
D902
17V
R912
Q902
P
P
Q901
F901
40A
R907
R908
D901
8.8V
R906
4.7k
Q903
N
0V
C801
22
+
P
20V
N
N
FIGURE 1-3 - POWER ON/AUDIO UNMUTE
N
11A125 1486 11/4/02
0V 9V
UNMUTE
Power ON
Refer to Figure 1-3. Power ON occurs when Battery +12Vdc passes through Q901 to the DC-DC Converter.
Q901 is turned on by Q903 that is turned on when at least 7.4Vdc is input the REM terminal. The 7.4Vdc
minimum turn ON threshold is set using an 8.8V zener D901 at Q903/collector. When Q903 conducts almost
fully (requiring 7.4V input), then zener D901 conducts. Current flows from Q901/emitter – base, through D901
and Q903 to ground. When Q901 conducts, Battery +12V is applied to the DC-DC Converter.
Power ON Inhibit
Power ON is inhibited if the Battery +12Vdc rises to 17.6Vdc or above. Zener D902 and Q902 keep Q901 off
when the input voltage is excessive. If the car alternator output rises to 17.6V or above, current flows from the
40A fuse through Q902/emitter – base, R912 and D902 to ground, turning ON Q902. When Q902 conducts,
Q901/emitter to base is shorted (bypassed) so Q901 cannot conduct to turn ON the amplifier.
Audio Un-Mute
Refer to Figure 1-3. Audio is un-muted at power ON. When Q903 turns ON to power ON the amplifier, it also
turns on IC902 to start the un-mute process. When IC902/pin 3 goes LOW, both Q801 and Q802 conduct
bringing +20Vdc (at Q801/pin collector) into the two line switching transistors Q102 and Q202. The higher
voltages at both bases permits them to conduct and both line switching transistors pass the audio signal from
collector to emitter (same signal level at both terminals).

6
1. Car Power Amplifier
1
2
Q903
POWER
ON/OFF
Q901, 902
B+
SWITCH
IC902
DC
DET.
Q813
LED
DRIVE
Q812 PROT.
LATCH
Q809
LED
INHIBIT
Q811
LED
DRIVE
Q810
PROT.
LATCH
12
3
1
2
15
16
14
REF.
REG.
10
11
9
8
Q904/5
Q906/7
D808
D811
POWER
THERMAL
THP802-3,
TH801-813
TEMP. DET.
D810
OFFSET
D809
OVER CURRENT
REM
12V
GND
Q808
IC901
DC-DC
CONVERTER
TO Q801,802 FROM
OFFSET
DETECT
CIRCUIT
FROM
OVER
CURRENT
CIRCUIT
F901
D807 D803
FIGURE 1-4 - POWER SUPPLY
TO T901
T901
+12V
FROM
F901
1.2V
REF.
TEMP LATCH
SW.+12V
0.2V
0V
OSC.
STOP
STOP
5.0V
1
1A125 11/12/02
OSC.
START
Pulse Power Supply – Oscillator / Output
Refer to Figure 1-4 (oscillator) and 1-5 (driver). The switching power supply consists of the oscillator within
IC901, the MOSFET drivers (Q904-8) transistors and the multiple winding transformer (T901) that it feeds.
Circuit Operation
IC901’s internal oscillator starts and produces a 36kHz output at pins 9 and 10 when four conditions are met:
1. Vcc is applied to IC901/pins 8, 11 and 12 of at least 5.9Vdc (normally = battery voltage).
2. Protection Latch 1 and 2 applied to IC901/pin 1 is less than 1.2Vdc.
3. Thermal Sensing voltage applied to IC901/pin 16 is less than 1.2Vdc.
4. Feedback for regulation at IC901/pin 4 (not shown) is less than 3Vdc.

7
1. Car Power Amplifier
R930 R931
Q908
0.7V
0.3V
Q909
0.3V
0.7V
R918 R942
R913
R914
R932 R933 R919
R915
R917
R943
R922
R920
C942 C919 C918 C917
*ALL
CAPACITORS
2200 18V
TO
REGULATION
0.6V
14.6V
Q906
0.6V Q907 FROM
IC901
PIN 9
FROM
IC901
PIN 10
R916 0.7V
Q904
0.7V
14.6V
14.6V
R921 Q905 B+
T901
DC-DC
CONVERTER
TRANSFORMER
FIG.1-5 POWER SUPPLY PRIMARY
0.3V
++ + +
* NOTE CAPACITOR
VALUES
C916
5A125 1458 11/11/02
14.6V
Referring to Figure 1-5, the oscillator signal is output and amplified by Q904 - Q907, which are four MOSFET
devices that feed T901. Q908 and Q909 are spike overload prevention transistors that prevent Q904/5 from
conducting at the same time Q906/7 are conducting and vice versa. For example, when a positive signal is
output IC901/pin 10, the positive drivers Q904/ Q905 turn ON. Prevention transistor Q909 also turns ON and in
doing so grounds any turn on signal to the negative drivers, Q906 and Q907 because only one set of drivers
should be ON, not both.
Pulse Power Supply – Testing
The MOSFETs can be tested with an ohmmeter. There is astatic test for shorts (Table 1-2) and an
operational test for functionality.
Table 1-2 -Static MOSFET Resistance Tests
Apply DVM Probes at: + / --/ +
Gate –Source Infinity Infinity
Gate -Drain Infinity Infinity
Drain -Source There is a zener diode connected internally
across these terminals
Power MOSFET
P or N channel
TO-220 case
D
G D S

8
1. Car Power Amplifier
5 7
3
21 6
57
2 1 6 7
5
67 3
21
Q101
LEVEL
SHIFT
Q801, 802
LINE SWITCH
CONTROL
IC901
GND.
ISOL.
Q903
POWER
ON/OFF
OFF
LPF
HPF
TO DIFFERENTIAL
AMPLIFIER STAGE
S901-1
FILTER
RV104-1
LEVEL
Q102
LINE SWITCH
RV103-1
LOW
BOOST
IC104(2/2)
LOW
BOOST IC104(1/2)
LINE AMP.
RV801-1
FILTER
IC102(2/2)
H.L.F.
+
-
+
-
+
-
-
+
RV101-1 FILTER
INPUT
L
CNJ801-1 IC101(1/2) PRE-AMP IC101(2/2)
PRE-AMP
IC102(1/2)
L.P.F. IC103(2/2) L.P.F.
FIGURE 1-6 - LEFT CHANNEL INPUT AUDIO STAGES
RV801-2
FILTER
3A125 1456 11/12/02
Operational test
To prove the device is functional:
1. Connect the negative lead of the ohmmeter to the SOURCE lead.
2. Touch the ohmmeter positive lead to the gate to pre-charge it.
3. Connect the ohmmeter positive lead to the DRAIN.
If the device is good, you will get a resistance reading of about 400-1k ohms.
Audio Processing–InputStages
Refer to Figure 1-6 and Table 1-3 for the location and signal output of each audio stage. The left channel is
shown but the right channel is similar. With all the filter controls set at mid rotation and a 1Vp-p 1kHz signal input,
the signal levels are shown in table 1-3 as they pass through the op-amp stages. S901 filter switch is OFF. The
audio ground is used (at the input jack or speaker output).
Table 1-3 -Audio Signal Levels
Location Level Location Level Location Level
IC101/pin 3 0.4 Vp-p IC102/pin 7 1 Vp-pIC104/pin 5 0.7 Vp-p
IC101/pin 1 1 Vp-p IC102/pin 2 0IC104/pin 7 1.3 Vp-p
IC101/pin 6 0 IC102/pin 1 0.1 Vp-pIC104/pin 3 1.3 Vp-p
IC101/pin 7 1 Vp-p IC103/pin 6 0IC104/pin 1 6 Vp-p
IC102/pin 5 0.4 Vp-p IC103/pin 7 20 mV Q102/any 6 Vp-p
Conditions: 1Vp-p, 1kHz input, Controls at mid rotation, switches = OFF.

9
1. Car Power Amplifier
FIGURE 1-7 - LEFT CHANNEL AUDIO OUTPUT BLOCKS
MUTE FROM
DC-IN
DETECT IC902
Q114 - 116
OVER CURRENT
DET.
Q103
DIFFERENTIAL
AMP.
Q105
DRIVE
AMP.
Q108, 110,
112
POWER AMP.
Q104
DIFFERENTIAL
AMP.
Q109, 111, 113
POWER AMP.
Q106
DRIVE AMP.
Q107
BIAS
Q102
LINE
SWITCH
RV105
BIAS TO Q813
TO Q803
(DC OFFSET
DETECT)
2
1SPEAKER
OUT L
CN804
4A125 457 11/12/02
-50V
+50V
+50V
-50V
Audio Processing – Output Operation
Refer to Figure 1-7. With 1 Vp-p input to the amplifier, there is about 6 Vp-p applied to the output stage at line
switch Q102. This output stage has two input differential amplifier stages instead of one. This keeps the output
stage balanced under severe operating conditions but is a little more difficult to troubleshoot.
The 6 Vp-p input signal is AC coupled into the output stage and split so the positive part of the signal is handled
by Q103 and the negative part is handled by Q104. The following drive amplifier (Q105/6) is a voltage amplifier.
TheoutputMOSFETs(Q108-Q113)providenovoltagegainbutsupplythecurrentnecessarytodrivethespeaker’s
voice coils. Just as with bipolar transistors, MOSFETs must also be pre-biased (Q107) so they are on the verge
of conduction.
Audio Processing – Output Troubleshooting
Refer to simplified output Figure 1-8. To fix this power output stage, we first need to DC balance this stage so it
outputs 0Vdc to the speakers. Once the stage is balanced, signal can output. Lastly, the bias control is adjusted
for minimum distortion under load, completing the repair of this stage.
Balancing the Stage
The output stage operates like an operational amplifier, requiring DC feedback from the output to the input
(R143). This feedback offsets the input differential stage to keep the average output at 0Vdc despite resistor and
gain variations within the stage.
Refer to the inset schematic of the input differential amplifier (left side of) Figure 1-8). Follow the current path
from the +50Vdc to the –50Vdc point. With equal value resistors (47k) and equal but opposite (+50Vdc) supply
voltages, the base at the center of the voltage divider string should be at 0Vdc. This means that the output at
both emitters should be +0.6Vdc respectively. This 0.6Vdc is placed at the emitters of the following transistors
(Q103 and Q104 in Figure 1-8), placing them balanced and at the verge of conduction.

10
1. Car Power Amplifier
R133
47k
EC1
B1
B2
Q104
C2
+50V
+
C123 R144
2.2k
AUDIO VIA
LINE SW.
IC102/E
PP
D103
15V
R132
4.7k
-50V
Q107
BIAS
CONTROL
R128
220
+50V
+REF
(+39V) 0.22
OHM
0.22
OHM
R140
100k
Q109,
Q111,Q113
P CH.
Q108
Q110,Q112
N CH.
-50V
+50V
-50V
DC FD BK
R134
47k
LEFT
SPEAKER
OUTPUT
EB2
C2
C1
B1
Q103
R139
100k
R143
8.8k
47
OHM
47
OHM
D101
15V
R131
4.7k R135
220
Q106 -2.5V
+2.5V D
S
D
S
N
NNP
Q104
B1B2
C1C2
+50V
47k
R144 REF.
47k
-50V
R143
REF.
DC
FD BK
FIGURE 1-8 - Bi-PHASE OUTOUT STAGE TROUBLESHOOTING
E
Q105
13.A125 1489 11/12/02
INSET
-REF
(+39V)
Referring to the main schematic of Figure 1-8, we can see that if the voltages at the emitters of Q103 and Q104
are both 0.6V but of opposite polarity, they will conduct equally (balanced), producing the same voltages at their
C2 collectors (also of opposite polarity). The driver stage (Q105, 6) that follows is symmetrical in the same
manner. Theircollector load resistors are 100k (R139 andR140). The junction ofthese resistors connectsto the
speaker and to feedback resistor R143. The speaker completes the current path to an audio ground. (Ground
side of the speaker not shown.) Feedback resistor R143 provides an offset correction voltage to the center of the
voltage divider string (Q103 & Q104 / B1) if the top and bottom amplifiers components were not perfectly
symmetrical.
Troubleshooting
Troubleshooting to a stage separated by a coupling capacitor is the job of a scope. Once the defective stage has
been found, a DC voltmeter and mental logic are the most valuable tools to detect damaged parts within that
stage. Theoutput stage consistsofpartsthatcanbe grouped:differentialamplifier(s),driversandoutput transistors.
The differential amplifiers and drivers are balanced and are all set at the verge of conduction (class B). Even
without the output transistors present, the differential amplifiers and drivers can produce a perfect signal on a
scope. Of course since the output transistors are not connected, a (speaker) load must not be connected. This
is the basis for the troubleshooting method and testing.
Note: Repair procedures you and I have used for more common single differential amplifier do not work in this
Bi-Phase dual differential output stage system. The Bi-Phase system tends to balance well and mask the
problem, so separating the parts of the output stage to isolate the problem further requires a new method /
procedure.

11
1. Car Power Amplifier
Prerequisites:
•The output transistors need not be connected. It is best to not have them connected unless you know they
are all good. If one were leaky, it will cause an imbalance in the entire stage so you could not tell if the
imbalance was in the outputs or input. Remove them to properly test the early differential amp and drivers.
•No load should be connected to the amplifier.
•The protection circuit may be disabled to allow the power supply to operate for troubleshooting. The input
current mustbe limited to 1 amp if the protection is disabled. See Protection Circuits for the location
of D803 / D807 to disable.
Procedure:
1. With the output transistors removed from that channel, power up the amplifier. The normal speaker voltage
(at the junction of R139 and R140) will be 0Vdc+0.1Vdc if the remaining circuitry is OK. If the normal 0Vdc
is now present, one or more of the removed output transistors is defective.
2. If the amplifier still shuts down (if you did not remove D803 / D807) or 0Vdc is not present at the junction of
R139 and R140, there is a problem with the differential amplifier or driver transistors. Disable the protection
circuit (see protection circuit) to allow the amplifier to power up and continue.
3. Disconnectthefeedbackresistor(R143inFigure1-8). Thespeakeroutputvoltagewillbenormallyunbalanced
to about +15Vdc with a +50Vdc supply voltage (even on a working amplifier) without this resistor but your
unbalanced voltage may be as high as +50Vdc or –50Vdc because of the defect.
Information–Inthenextstepsyouwillfirstcheckbalanceandthencheckbiasvoltage. Withtheoutputtransistors
removed and+powerappliedtotheoutputstage, all theremainingtransistorsshouldbeon thevergeofconduction
(0.6Vdc at each base – emitter junction) and the differential amp reference should be 0Vdc.
4. Check the differential amp reference voltage first. Measure the voltage at B1 with respect to audio ground.
It should be 0Vdc if R133, R134, Q103, Q104 and C123 are OK. These parts form a voltage divider between
+50V and –50V yielding exactly 0V at the middle of the divider (B1).
5. Measure the base – emitter bias voltage of each transistor and note, which ones are below 0.59Vdc.
6. When you find a transistor below bias, look at the simplified schematic (Figure 1-8, left inset) and find the
current path of the transistors that are not biased.
7. Test the parts in the path.
For example, if both Q104 and Q106 base – emitter voltages were below 0.59Vdc, the path of components to
test would be Q104 (part 2), D103, Q106 and R138.
8. Reconnect feedback the resistor (R143).
9. After repairs to the differential amp / driver transistors, preset the bias control* for +0.55Vdc or +1Vdc (see
below) before installing the output devices.
•Bipolar transistors = 0.55Vdc
•MOSFET (Q109, Q108) = +1Vdc at the gate of the output
* If the bias control has not been damaged when the output devices failed, the voltage will change gradually
as the control is turned. If the control is unstable, the output devices will fail prematurely.
10. Install the output transistors and power up the amplifier.
11. Adjust the bias control as recommended in the service manual for that model.

12
1. Car Power Amplifier
1
2
Q903
POWER
ON/OFF
Q901, 902
B+
SWITCH
IC902
DC
DET.
Q813
LED
DRIVE
Q812 PROT.
LATCH
Q809
LED
INHIBIT
Q811
LED
DRIVE
Q810
PROT.
LATCH
12
3
1
2
15
16
14
REF.
REG.
10
11
9
8
Q904/5
Q906/7
D808
D811
POWER
THERMAL
THP802-3,
TH801-813
TEMP. DET.
D810
OFFSET
D809
OVER CURRENT
REM
12V
GND
Q808
IC901
DC-DC
CONVERTER
UNMUTE TO
Q801,802 FROM
OFFSET
DETECT
CIRCUIT
FROM
OVER
CURRENT
CIRCUIT
F901
D807 D803
FIGURE 1-9 - PROTECTION CIRCUIT 1 - THERMAL
TO T901
T901
+12V
FROM
F901
1.2V
REF.
TEMP LATCH
SW.+12V
0.2V
0V
OSC.
STOP
STOP
5.0V
1
1A125a 11/11/02
SEE FIG.1-5
Protection Circuit – PS Oscillator Stop 1 (Thermal)
Concept
Refer to Figure 1-9. The power supply oscillator within DC-DC Converter IC901 starts when voltage is applied to
pin 12. This 36kHz oscillator can be stopped for amplifier protection if the voltage at pins 1 or 16 rises to 1.2Vdc.
The protection circuits external to IC901 keep this voltage latched high (oscillator = OFF) when the circuit is
tripped.

13
1. Car Power Amplifier
Table 1-4 shows the normal operating voltages of IC901.
Table 1-4 -IC901 uPC494GS-F1 -Normal Operating Voltages
IC901/pin Voltage IC901/pin Voltage IC901/pin Voltage
1 (protect
input) 0 Vdc 7 (gnd) 0 Vdc 13 (reg out)
5 Vdc
2 (ref in) 1.28 Vdc 8 (Battery in) 14 Vdc 14 (reg out) 5 Vdc
3 (latch
output) 0.11 Vdc
(5V = tripped) 9 (osc out +) 3.5 Vdc 15 (ref in) 1.28
Vdc
4 (reg
input) 0.6 Vdc
(1.2 V = tripped)
10 (osc out -) 3.5 Vdc 16 (thermal
input) 0.14 Vdc
5 (internal) 1.7 Vdc 11 (Battery in) 14 Vdc
6 (internal) 3.7 Vdc 12 (Battery in) 14 Vdc
Batt
+12V 5V Reg in IC901 R1
Protection
Circuit in
IC901
Thermal LED
14
12
24k ohm
thermistor
TH-xxx
D1
.1V 0.17V
16
3
0V
TH Thermistor Circuit
Figure 1-10a - Thermal Stop Circuit - TH Thermistors used (simplified)
Operation
The first protection circuit monitors the temperature of the amplifier using two or more thermistors on the circuit
board (one near each heat sink). The thermal triggered oscillator stop circuit is shown in Figure 1-10a. The
other thermistor circuits are in parallel between IC901/pins 14 and 16.
There are “TH” prefixed negative temperature coefficient thernistors or “THP” positive coefficient ones depending
upon availability at the time of manufacture. The TH and THP require different circuit configurations.
TH Thermistors - The “TH” thermistor measures 24k ohms out of circuit and decrease in resistance when warm.
In the configuration of Figure 1-10a, the thermistors are connected to regulated 5Vdc from IC901/pin 14 at one
end and to the anode of an isolation diode at the other. The cathode outputs are all connected to one protection
input at IC901/pin 16.

14
1. Car Power Amplifier
Q118-Q113
OUTPUT
STAGES
+-
+-
LEFT
RIGHT
Q114-6, Q214-6, Q812-3
OUTPUT CURRENT
DETECTION
OSC. TO DC-DC
CONV. IC901/PIN 1
D810
OFFSET
CN806/
CN807 1R814
D803
D807
-14.2V
LED BD.
LATCH-1
P
N
R825
R826
Q811
Q810
C808
22 +
R822 R823 14.2V
R153
470k
R253 470k
N
Q805
INV
R807 14.2V
0VDC
CN804
CN805
R810
1M
R806
N
MAIN BD.
C803
47 +
R808
R809
Q803
OFFSET +
Q804
OFFSET -
OFFSET ERROR
L
R
FIGURE 1-11 - PROTECTION CIRCUIT 2 - OFFSET 9A125 1484 11/12/02
P
When the amplifier gets hot, the TH thermistors decrease resistance, increasing the voltage at IC901/pin 16. If
the voltage reaches the trip point of 1.2Vdc, IC901’s internal power supply oscillator stops, removing supply
voltage to the amplifier. IC901 additionally outputs 5Vdc from pin 3 to keep the amplifier latched OFF and the
Thermal LED ON via R1.
THP thermistors - If the THP thermistors are used, the thermistor circuit is changed. THP thermistors are
normallylessthan5kohmscoldandincreasewithtemperature. InthesimilarcircuitofFigure1-10b,anincreasing
thermistor resistance also brings the voltage at IC901/pin 16 up.
R2
R1
Protection
Circuit in
IC901
Thermal LED
THP-xxx
D1
.1V 0.17V
16
3
0V
THP Thermistor Circuit
Figure 1-10b - Thermal Stop Circuit - THP Thermistors used (simplified)
Batt
+12V 5V Reg in IC901 14
12
Testing
To find out which thermsitor keeps triggering the thermal protection LED / circuit, run the amplifier and measure
the voltage at each diode / anode (D1 in Figure 1-10 or TH801-813 in Figure 1-9) that is connected to the
thermistor. Normally each point is 0.1Vdc (cool room temperature). The trip voltage is 1.9Vdc before the diode.
A voltage near the trip point means the related thermistor is bad or the transistors near that thermistor are
overheating. Adjust the bias in that channel or switch the suspected thermistor with another on the board. Idle
current is typically 1 amp at 13Vdc (no input or load).
ProtectionCircuit–OscillatorStop2(Offset)
Concept
The offset protection circuit monitors both amplifiers for an average voltage of 0Vdc and shuts off IC901’s
oscillator if this voltage averages above 0.6Vdc. The latch circuit external to IC901 keeps the oscillator OFF as
long as REM input voltage (power ON) is present.

15
1. Car Power Amplifier
Operation
Refer to Figure 1-11. The offset protection circuit consists of: an imbalance circuit (Q803-804), a latch circuit
(Q810-811), the LED indicator (D810) and the oscillator stop circuit inside IC901 (via pin 1). Both left and right
audio output channels are sampled at the speaker output via R153 and R253. This audio voltage should be 0V
+0.2Vdc with no audio input. That should also be the average dc voltage of the audio in normal operation as well,
proving there is no thermal leakage in one of the output transistors or MOSFETs.
C803 averages out the audio that may be present on the speaker lines and the resultant DC is applied to Q803
and Q804/base. If the average voltage rises to +0.6Vdc, one of the two transistors is turned ON. The one that
isturnedONmomentarilygroundsQ811/baseandactivatesthelatch. ThelatchinvertsthisLOWinput,producing
a constant HIGH output Q811/collector. The HIGH output is used to light the Offset LED (D810) and stop the
power supply oscillator (IC901/pin 1) via D803.
Testing
The offset light means that either noise spikes are being input to the audio input then passed out, or there is a DC
imbalance in one of the output channels (leaky output transistor).
Shutdown after power ON - Since the positive or negative offset cause is not stored, your best clue to the
imbalanced channel is the DC offset voltage to the speaker before the protection circuit activates and removes
power (latches Off).
Once you have identified the defective channel, remove all the output transistors from that channel and re-
measure the speaker voltage (without speakers connected). If the voltage is now 0Vdc, the differential amplifier
part of the output stage is balanced and working and one of the output transistors you removed was defective
(see Audio Processing – Output Troubleshooting).
Shutdown when hot - Note the speaker DC voltage cold, then hot. If either channel is above 0.2Vdc, or increases
considerably when hot, that channel is suspect. The trip point is+0.6Vdc at the speaker terminals.
Protection Circuit – Oscillator Stop 3 (Current)
Concept
Six protection transistors monitor the current drawn by six pairs of +output transistors. If the average current to
the speaker from these output transistor pairs exceeds the threshold for that model, latch –2 (Figure 1-12) will
turn OFF the power supply oscillator (IC901).

16
1. Car Power Amplifier
AUDIO
OUTPUT
(SPK) R159
1k
+AUDIO
Q105/C
-AUDIO
Q105/C
LED BD. OVER
CURRENT
R813
Q803-5, Q810-1
OFFSET DETECTION
CIRCUIT
R830
OSC. STOP
TO DC-DC
CONV. IC901/PIN 2
R827
10k
R829
R828
C809
4.7
+
+50V
R258
R185
10k
R158
2.2k Q114
I DET-L
N
N
Q109
P CH.
Q108
N CH.
R145
R148
-50V
14.2V
Q813 PD807
D803
2
0V
14.2V
14.2V
Q812
SAMPLE OUTPUT DRIVER PAIR
LATCH
-2
I ERROR
FIGURE 1-12 - PROTECTION CIRCUIT 3 - OVER CURRENT
R166
R158
R285 R266
I DET-R
Q216
I DET-R
Q214 I DET-R Q215
I DET-L
Q116
I DET-L
Q115
10A125 1485 11/12/02
Operation
Refer to Figure 1-12. The same current that flows in the speaker also flows through the output transistors and
their emitter resistors (R145 and R148). By sampling the voltage across the two emitter resistors using Q114,
the maximum speaker current can be detected. The values of R158, R159 and the gain of the Q114 transistor
set the maximum current.
Whenthecurrentthresholdisreached,0.6VdcmomentarilyappearsacrossQ114’sb-ejunction. Q114conducts
and lowers the 14.2Vdc at the input of the latch at Q812/collector. The Q812 and Q813 latch change the input
LOW to a constant (latched) output HIGH. This HIGH from Q813/collector is applied to light the Over Current
LED and stop the power supply oscillator (IC901/pin 1) via D807.
Testing
An Over current LED indication is often caused by a short circuit in the speaker wiring or too many speakers are
used. Within the amplifier, an output transistor that is lower in gain than the others could cause the Overcurrent
LED to latch ON. If you can run the amplifier for at least 5 minutes at the rated output without an Overcurrent trip,
the problem is external to the amplifier in the car wiring.

17
2. Satellite Radio - The Third Band
Chapter 2 - Satellite Radio
XM©vs.Sirius©Radio
In the continental USA, two companies are each offering over 100 digital channels consisting of music, sports,
news and entertainment. XM© Radio first started in September 2001 and Sirius© Radio began in July 2002.
Subscription rates and programming are similar. See Table 2-1 below:
Table 2-1 -Satellite Radio Comparison
XM© Radio Sirius© Radio
Activation * / monthly fee $15. ($10. On-line) / $9.99 $15 / $12.95
Hardware Rebates (9/02) $50. $75.
Hardware Manufacturers Sony, Pioneer, Alpine. Clarion, Jensen, Kenwood.
Reception AreaContinental USA Continental USA
HQ Location Washington, DC New York City
Contact
(website has music
samples)
www.xmradio.com
1-800-852-9696 www.sirius.com 1-888-539-7474
Free Start Channel
* Unit must receive station
to begin activation.
Channel 1 (sample satellite
music) Channel 184 (satellite voice)
Auto Partners GM, Honda, Isuzu, VW, Audi. Daimler Chrysler, Ford,
BMW, Mercedes, Jaguar,
Volvo, Mazda, Dodge,
Jeep.
SystemOperation
Refer to Figure 2-1. An XM© radio is currently available as an “add on” to a stereo system either in the car or in
the home (top and middle radio in Figure 2-1). Later the XM© system will be added to a portable boom box and
AM/FM car receivers (upgrade to XM© radio in the bottom part of Figure 2-1).

18
2. Satellite Radio - The Third Band
XM© Radio Components
The XM© radio must be connected to 12V power and an active antenna. The XM© radio will not work without the
antenna (powered from the radio).
Sony has two XM© satellite radio models. Refer to Figure 2-1. The hide away XM© radio unit connects to the
specially marked AM/FM receiver (“XM© Satellite Radio Ready”). Joined by a “Uni-Link” cable (power, audio and
communications), the AM/FM receiver now displays the third band XM© radio information.
The second XM© radio plugs into a clamshell shaped holder. This permits the radio to either plug into the car
holder or the holder at home. Each location must have a powered antenna connected to the holder as well as
power. The line output goes into the stereo receiver.
Theantenna is a combination powered satellite antenna and terrestrial antenna in one package. The two antenna
cables that output plug into the XM© radio / clamshell holder. Two antennas are used to insure reliable signal
especially when the radio is mobile. For example if the satellite signal is lost in a tunnel, the radio may still be
able to pick up a terrestrial signal from a local repeater.
Activation
Activation of the radio hardware is done on line (Internet) or by phone. The customer must have:
1. The ID or ESN number of the radio.
2. Be receiving the satellite signal (XM© = channel 1; Sirius© = channel 184).
3. Credit card.
WASHINGTON D.C.
XM RADIO .COM
REPEATERS
TER TER TER
SATELLITE
ANTENNA
ROOF OR GLASS
ANT.
XM© RADIO
S/N ON CH 0
AM/FM/XM©
3 BAND RADIO
CD PLAYER
ANT.
XM© HIDEAWAY
SAT TER
ANT.
AM/FM/XM©
CONTROLLER
2 SATELLITES TO
COVER USA
UPLINK
SAT TER
CROSS COUNTRY GROUND ANTENNAS
CAR
ANT.
ADD
ON
XM©
CASSETTE
ADAPTER
CAR & HOME
PLUG-IN
L & R LINE
OUT
UNI-LINK
CABLE
AM/FM/CASS.
CAR
ANT.
UPGRADE
TO XM©
RADIO
ANT.
FIGURE 2-1 - XM© SATELLITE RADIO 15A125 1495 11/20/02