XM-GTX1821 - 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.

1.  Short across TH301 (short between TP19 and TP20) with the 
 power 

on.

2.  Verify that the protector is operated and D904 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 TH302 (short between TP19 and 

TP21) and TH303 (short between TP19 and TP22).

1.  Short between the positive and negative sides of the speaker output 

terminal TB901 with the power on.

2.  Verify that the protector is operated and D904 illuminates red.
3.  Verify that the protector is not released and D904 remains red even 

when the short is removed.

4.  Verify that the protector is released and D904 illuminates green
 

when the power is turned off and then on again.

1.  Short between the +12V terminal of TB901 and the BTL + 
 or 

BTL 

 of the speaker output terminal TB901.

 

(Short between +12V terminal and BTL + and between +12V 

 

terminal and BTL 

.)

2.  Verify that the protector is operated and D904 illuminates red.
3.  Verify that the protector is not released and D904 remains red even 

when the short is removed.

4.  Verify that the protector is released and D904 illuminates green
 

when the power is turned off and then on again.

NOTE  FOR  REPLACEMENT  OF  THE  TRANSISTORS
The transistors Q113, 114, 116, 117, 119, 120, 213, 214, 216, 217, 
219 and 220 have two different ranks: P rank and Y rank.
The rank of these transistors need to be selected properly 
according to each channel. When replacing any one of these 
transistors, check its rank and replace with the appropriate 
transistor of the same rank.

Rank

Q113, 116, 119,

213, 216, 219

Q114, 117, 120,

214, 217, 220

P

2SC5100-P

2SA1908-P

Y

2SC5100-Y

2SA1908-Y