Sony cdp h3750 2

Page 2

CDP-H3750

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 microampers). Leakage
current can be measured by any one of three
methods.

I. A commercial leakage tester, such as the
Simpson 229 or RCA WT-54OA. Follow the
manufacturers instructions to use these instru-
ments.

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 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
0.15uF 1.5km / voltmeter
(0. 75 V}

? Earth Ground

Fig. A. Using an AC voltmeter to check AC leakage.

NOTES ON HANDLING THE OPTICAL PICK-UP
BLOCK 0R BASE UNIT

The laser diode in the optical pick-up block may suffer
electrostatic breakdown because of the potential diference
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 from more than 30cm away from the
objective lens. I

LASER DIODE AND FOCUS SERCH OPERATION CHECK

1. Make POWER switch on with no disc inserted and disc
table closed.

2. Confirm that the following operation is performed while
observing the objective lens.

OConfirm that laser beam is spread.
0 Up and down motion of the objective lens. (3 times)