Sony CDX-GT420U Service Manual page 3

SAFETY-RELATED COMPONET WARNING!
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
WHOSE PART NUMBERS APPEAR AS SHOWN IN THIS
MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.
CDX-GT420U/GT424U/GT427UE/GT470U/GT470US
WITH SONY PARTS
SERVICE NOTES
NOTES ON HANDLING THE OPTICAL PICK-UP
BLOCK OR BASE UNIT
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
The laser beam on this model is concentrated so as to be focused
on the disc refl ective surface by the objective lens in the optical
pickup block. Therefore, when checking the laser diode emission,
observe from more than 30 cm away from the objective lens.
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.
TEST DISCS
Please use the following test discs for the check on the CD section.
YDES-18 (Part No. 3-702-101-01)
PATD-012 (Part No. 4-225-203-01)
CAUTION
Use of controls or adjustments or performance of procedures other than
those specifi ed herein may result in hazardous radiation exposure.
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.
semi-fixed resistor
optical pick-up
3