MEX-BT4700U, MEX-BT4750U - Sony Car Audio Service Manual (repair manual). Page 3

The laser diode in the optical pick-up block may suffer electrostat-
ic break-down because of the potential difference generated by the 
charged electrostatic load, etc. on clothing and the human body.
During repair, pay attention to electrostatic break-down and also 
use the procedure in the printed matter which is included in the 
repair parts.
The fl exible board is easily damaged and should be handled with 
care.

NOTES  ON  LASER  DIODE  EMISSION  CHECK
Never look into the laser diode emission from right above when 
checking it for adjustment. It is feared that you will lose your 
sight.

If the optical pick-up block is defective, please replace the whole 
optical pick-up block.
Never turn the semi-fi xed resistor located at the side of optical 
pick-up block.

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.

TEST  DISCS
Use following TEST DISC when this set confi rms the operation 
and checks it.

Part No.   

Description

3-702-101-01 

YEDS-18 (for CD)

4-225-203-01 

PATD-012 (for CD)

NOTE  FOR  THE  20-PIN  CONNECTOR (CN901)
Do not use alcohol to clean the 20-pin connector (CN901) connect-
ing the front panel with the main body.
Do not touch the connector directly with your bare hand. Poor con-
tact may be caused.

EXTENSION  CABLE  AND  SERVICE  POSITION
When repairing or servicing this set, connect the jig (extension cable) as shown below.

•  Connect the MAIN board (CN350) and the SERVO board (CN401) with the extension cable (Part No. J-2502-076-1).