XM-ZR4A - Sony Car Audio Service Manual (repair manual). Page 2

UNLEADED  SOLDER
Boards requiring use of unleaded solder are printed with the lead-
free mark (LF) indicating the solder contains no lead.
(Caution:  Some printed circuit boards may not come printed with 

the lead free mark due to their particular size)

Unleaded solder has the following characteristics.
•  Unleaded solder melts at a temperature about 40 °C higher 

than ordinary solder.

 

Ordinary soldering irons can be used but the iron tip has to be 
applied to the solder joint for a slightly longer time.

 

Soldering irons using a temperature regulator should be set to 
about 350 °C.
Caution: The printed pattern (copper foil) may peel away if 

the heated tip is applied for too long, so be careful!

• Strong 

viscosity

 

Unleaded solder is more viscous (sticky, less prone to fl ow) 
than ordinary solder so use caution not to let solder bridges 
occur such as on IC pins, etc.

• 

Usable with ordinary solder

 

It is best to use only unleaded solder but unleaded solder may 
also be added to ordinary solder.

 

Location and Function of Controls .................................   3

 Connections 

....................................................................  

4

2-1.   Bottom Plate ....................................................................   7
2-2.   MAIN Board Section .......................................................   8
2-3.   LED1 Board, LED2 Board ..............................................   8
2-4.   MAIN Board ....................................................................   9

3-1.   Block Diagram .................................................................   11
3-2.   Printed Wiring Boards .....................................................   12
3-3.   Schematic Diagram –Main Section (1/3)– ......................   13
3-4.   Schematic Diagram –Main Section (2/3)– ......................   14
3-5.   Schematic Diagram –Main Section (3/3)– ......................   15

4-1.   Heat Sink (Main) Section ................................................   17
4-2.   MAIN Board Section .......................................................   18

ELECTRICAL  PARTS  LIST ............................   19

NOTES  ON  CHIP  COMPONENT  REPLACEMENT
• 

Never reuse a disconnected chip component.

• 

Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.

Thermal Protect
1.  Short across TH901 (short between TP24 and TP19) with the 

power on.

2.  Verify that the protector is operated and D918 illuminates 

green. When input the signal and verify that there is no output 
on the SP-OUT even when the volume is increased.

3.  Verify that the protector is released and there is an output on 

the SP-OUT when the short is removed.

4.  Likewise, perform items 1 to 3 for TH902 (short between 

TP23 and TP19), TH903 (short between TP22 and TP19), 
TH904 (short between TP21 and TP19) and TH905 (short 
between TP20 and TP19).

Over Current Protect
1.  Short between the positive and negative sides of the speaker 

output terminals CN903 (1/2), CN903 (2/2), CN904 (2/3) and 
CN904 (3/3) with the power on.

 

(Perform this shorting for each channel on REAR and 
FRONT.)

2.  Verify that the protector is operated and D918 illuminates red.
3.  Verify that the protector is not released and D918 remains red 

even when the short is removed.

4.  Verify that the protector is released and D918 illuminates 

green when the power is turned off and then on again.

Offset Protect
1.  Short between the +12V terminal of CN904 (1/3) and the 

(L+R) + or (L+R) – of the speaker output terminal CN903 
(1/2) and CN903 (2/2).

 

(Short between +12V terminal and (L+R) + and between 
+12V terminal and (L+R) –.)

2.  Verify that the protector is operated and D918 illuminates red.
3.  Verify that the protector is not released and D918 remains red 

even when the short is removed.

4.  Verify that the protector is released and D918 illuminates 

green when the power is turned off and then on again.

0  OR  DOTTED  LINE  

0  ON  THE  SCHEMATIC  DIAGRAMS  AND  IN  

0  SUR