Servicing Notes - Sony CFD-G70 Service Manual

SAFETY CHECK-OUT (US model)
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 pas-
sive 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
0.15 µ F
Fig. A. Using an AC voltmeter to check AC leakage.

SERVICING NOTES

AC
1.5k Ω
voltmeter
(0.75V)
Earth Ground
SECTION 1
NOTES ON HANDLING THE OPTICAL PICK-UP
BLOCK OR BASE UNIT
The laser diode in the optical pick-up block may suffer electro-
static 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 breakdown 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 more than 30 cm away from the objective
lens.
CHUCK PLATE JIG ON REPAIRING
On repairing CD section, playing a disc without the CD lid, use
Chuck Plate Jig.
• Code number of Chuck Plate Jig : X-4918-255-1
LASER DIODE AND FOCUS SEARCH OPERATION
CHECK
1. Press CD open knob.
2. Open the lid for CD.
3. Push on SWITCH (S801) as following figure.
4. Confirm the laser diode emission while observing the
objecting lens. When there is no emission, Auto Power
Control circuit or Optical Pick-up is broken.
Objective lens moves up and down once for the focus
search.
CFD-G70
Insert a precision
screw driver and push
SWITCH (S801)
3