XM-ZR1252 - 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.

COMPONENTS  IDENTIFIED  BY  MARK 0 OR  DOTTED  LINE  
WITH  MARK 0 ON  THE  SCHEMATIC  DIAGRAMS  AND  IN  
THE  PARTS  LIST  ARE  CRITICAL  TO  SAFE  OPERATION.
REPLACE  THESE  COMPONENTS  WITH  SONY  PARTS 

 

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

 Connections 

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

4

2-1. Bottom 

Plate 

...................................................................   8

2-2.  MAIN Board Section ......................................................   9
2-3. LED 

Board 

......................................................................   9

2-4. MAIN 

Board 

...................................................................  10

3-1. Block 

Diagram 

................................................................  11

3-2. Printed 

Wiring 

Boards 

....................................................  13

3-3. Schematic 

Diagram 

.........................................................  14

4-1.  Heat Sink (Main) Section ...............................................   16
4-2.  MAIN Board Section ......................................................   17

  ..............................   18

Thermal Protect
1.  Short across TH501 (short between JW89 and JW90) with the 

power on.

2.  Verify that the protector is operated and LED901 illuminates 

red.

3.  Verify that the protector is released and LED901 illuminates 

green when the short is removed.

4.  Likewise, perform items 1 to 3 for TH502 (short between 

JW174 and JW175) and TH503 (short between JW175 and 
JW176).

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

output terminal CN903 (1/2) with the power on.

2.  Verify that the protector is operated and LED901 illuminates 

red.

3.  Verify that the protector is not released and LED901 remains 

red even when the short is removed.

4.  Verify that the protector is released and LED901 illuminates 

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

Offset Protect
1.  Short between the +12V terminal of CN903 (2/2) and the BTL + 

or BTL – of the speaker output terminal CN903 (1/2).

 

(Short between +12V terminal and BTL + and between +12V 
terminal and BTL –.)

2.  Verify that the protector is operated and LED901 illuminates 

red.

3.  Verify that the protector is not released and LED901 remains 

red even when the short is removed.

4.  Verify that the protector is released and LED901 illuminates 

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

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.