Sony CDP-790 - SAFETY CHECK-OUT; LEAKAGE TEST; PROTECTION OF EYES FROM LASER BEAM DURING SERVICING; Laser Diode Properties

CDP-790
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 0.5mA (500 microampers). Leakage
current can be measured by any one of three
methods.
ie
A commercial leakage tester, such as the
Simpson 229 or RCA WT-540A. Follow the
manufacturers’ instructions to use these instru-
ments.
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 volt-
meter. 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
AC
voltmeter
a (0.75 V)
= Earth Ground
Using an AC voltmeter to check AC leakage.
POP OPO OPO DOPED ODL EDEL DOP OPED ODED OPED EPD OL OLE OOD A DEE ERED ELROD ODED ODED EL ODODE EMO OLED ROEDER OOOO OP OEE OME DOO:
This set employs a laser. Therefore, be sure to follow
carefully the instructions below when servicing.
CAUTION
Use of controls or adjustments or performance
of procedures other than those specified herein
may result in hazardous radiation exposure.
PROTECTION OF EYES FROM LASER BEAM DURING SERVICING
]. Laser Diode Properties
Material: GaAlAs
Wavelength: 780 mm
Emission Duration: continuous
Laser Output Power: less than 44.6 uW*
* This output is the value measured at a distance of
200 mm from the objective lens surface on the
Optical Pick-up Block.
2. During service, do not take the Optical Pick-up Block
apart, and do not adjust the APC circuit. If there is a
breakdown in the APC circuit (including laser diode),
replace the entire Optical Pick-up Block (including
APC board),
SERVICING NOTE
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
poten-
tial
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 30cm away from the
objective lens.