Sony HCD-GX25 Service Manual page 3

SAFETY CHECK-OUT
After correcting the original service problem, perform the following
safety check before releasing the set to the customer:
Check the antenna terminals, metal trim, "metallized" knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.
LEAKAGE TEST
The AC leakage from any exposed metal part to earth ground and
from all exposed metal parts to any exposed metal part having a
return to chassis, must not exceed 0.5 mA (500 microamperes).
Leakage current can be measured by any one of three methods.
1. A commercial leakage tester, such as the Simpson 229 or RCA
WT-540A. Follow the manufacturers' instructions to use these
instruments.
2. A battery-operated AC milliammeter. The Data Precision 245
digital multimeter is suitable for this job.
3. Measuring the voltage drop across a resistor by means of a VOM
or battery-operated AC voltmeter. The "limit" indication is 0.75
V, so analog meters must have an accurate low-voltage scale. The
Simpson 250 and Sanwa SH-63Trd are examples of a passive
VOM that is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)
To Exposed Metal
Parts on Set
0.15µF
Fig. A. Using an AC voltmeter to check AC leakage.
Notes on Chip Component Replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be
damaged by heat.
Flexible Circuit Board Repairing
• Keep the temperature of soldering iron around 270°C during
repairing.
• Do not touch the soldering iron on the same conductor of the
circuit board (within 3 times).
• Be careful not to apply force on the conductor when soldering
or unsoldering.
AC
1.5k Ω
voltmeter
(0.75V)
Earth Ground
CAUTION
Use of controls or adjustments or performance of procedures
other than those specified herein may result in hazardous
radiation exposure.
NOTES ON HANDLING THE OPTICAL PICK-UP BLOCK
OR BASE UNIT
The laser diode in the optical pick-up block may suffer electrostatic
breakdown 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 flexible 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 reflective surface by the objective lens in the optical pick-
up block. Therefore, when checking the laser diode emission,
observe from more than 30 cm away from the objective lens.
Laser component in this product is capable
of emitting radiation exceeding the limit for
Class 1.
SETTING AND RELEASING THE CD DISC TRAY LOCK
FUNCTION
This set has a disc tray lock function to prevent discs for
demonstration at shops from theft. While this lock function is set,
the tray will not be delivered out even when the OPEN/CLOSE
button is pressed.
Setting method:
Press the OPEN/CLOSE button while pressing the STOP button.
After a few seconds, the message "LOCKED" will appear on the
fluorescent indicator tube with the tray locked.
Releasing method:
Just as the lock is set, press the OPEN/CLOSE button while
pressing the STOP button.
After a few seconds, the message "UNLOCKED" will appear with
the lock released.
LASER DIODE AND FOCUS SEARCH OPERATION
CHECK
Carry out the "S curve check" in "CD section adjustment" and check
that the S curve waveforms is output three times.
HCD-GX25/RG220
3