Sony CPD-G420 (serv.man4) Service Manual ▷ View online
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CPD-G420
SAFETY CHECK-OUT
After correcting the original service problem, perform the following
safety checks before releasing the set to the customer:
safety checks before releasing the set to the customer:
1. Check the area of your repair for unsoldered or poorly soldered
connections. Check the entire board surface for solder splashes and
bridges.
bridges.
2. Check the interboard wiring to ensure that no wires are “pinched” or
touching high-wattage resistors.
3. Check that all control knobs, shields, covers, ground straps, and
mounting hardware have been replaced. Be absolutely certain that
you have replaced all the insulators.
you have replaced all the insulators.
4. Look for unauthorized replacement parts, particularly transistors,
that were installed during a previous repair. Point them out to the
customer and recommend their replacement.
customer and recommend their replacement.
5. Look for parts which, though functioning, show obvious signs of
deterioration. Point them out to the customer and recommend their
replacement.
replacement.
6. Check the line cords for cracks and abrasion. Recommend the
replacement of any such line cord to the customer.
7. Check the B+ and HV to see if they are specifi ed values. Make
sure your instruments are accurate; be suspicious of your HV
meter if sets always have low HV.
meter if sets always have low HV.
8. Check the antenna terminals, metal trim, “metallized” knobs,
screws, and all other exposed metal parts for AC leakage. Check
leakage as described below.
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.
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
instructions.
instructions.
2. A battery-operated AC milliampmeter. 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’s 250 and Sanwa SH-63TRD are examples of
passive VOMs that are suitable. Nearly all battery-operated digital
multimeters that have a 2 VAC range are suitable (see Figure A).
V, so analog meters must have an accurate low voltage scale.
The Simpson’s 250 and Sanwa SH-63TRD are examples of
passive VOMs that are suitable. Nearly all battery-operated digital
multimeters that have a 2 VAC range are suitable (see Figure A).
How to Find a Good Earth Ground
A cold-water pipe is a guaranteed earth ground; the cover-plate retaining
screw on most AC outlet boxes is also at earth ground. If the retaining
screw is to be used as your earth ground, verify that it is at ground
by measuring the resistance between it and a cold-water pipe with an
ohmmeter. The reading should be zero ohms.
A cold-water pipe is a guaranteed earth ground; the cover-plate retaining
screw on most AC outlet boxes is also at earth ground. If the retaining
screw is to be used as your earth ground, verify that it is at ground
by measuring the resistance between it and a cold-water pipe with an
ohmmeter. The reading should be zero ohms.
If a cold-water pipe is not accessible, connect a 60- to 100-watt trouble-
light (not a neon lamp) between the hot side of the receptacle and the
retaining screw. Try both slots, if necessary, to locate the hot side on the
line; the lamp should light at normal brilliance if the screw is at ground
potential (see Figure B).
light (not a neon lamp) between the hot side of the receptacle and the
retaining screw. Try both slots, if necessary, to locate the hot side on the
line; the lamp should light at normal brilliance if the screw is at ground
potential (see Figure B).
g
AC Outlet Box
Ohmmeter
Cold-water Pipe
Figure A. Using an AC voltmeter to check AC leakage.
Figure B. Checking for earth ground.
To Exposed Metal
Parts on Set
0.15 µF
1.5 K
Ω
AC
Voltmeter
(0.75 V)
Earth Ground
— 7 —
CPD-G420
1-1. CABINET REMOVAL
SECTION 1: DISASSEMBLY
1
B
B
A
A
C
C
Two screws
(+BVTP 4 x 16)
(+BVTP 4 x 16)
6
Slide the EMI shield in the direction
of arrow
of arrow
and remove four claws.
7
EMI shield
4
Four screws
(+BVTT 4 x 8)
(+BVTT 4 x 8)
5
Four screws
(+BVTT 4 x 8)
(+BVTT 4 x 8)
2
Two claws
3
Push the upper side of the cabinet
inthe direction of arrow
inthe direction of arrow
, disconnect claws,
then remove the cabinet
lifting it up in the direction of arrow
lifting it up in the direction of arrow
.
Bezel assembly
Bezel assembly
EMI shield
Cabinet
Cabinet
Push in the tip of a screwdriver
about 10mm to unlock the claw.
about 10mm to unlock the claw.
— 8 —
CPD-G420
1. When the D Board is placed
in service position, the
Safety Earth Wire
(green and yellow wire)
is disconnected.
2. After service is completed
and the D Board is
reinstalled, the
Safety Earth Wire must be
reattached to the chassis
with the proper screw. This
must be confi rmed before
any subsequent procedures
are attempted.
1-2. SERVICE POSITION
1
2
3
4
1
Remove the D board.
D board
2 Remove the Video block assembly.
3 Install the Adaptor board (XT MOUNT) (A-1391-123-A).
4 Lay the Video block assembly.
Video block assembly
Video block assembly
5
5
Install the video block assembly.
6 Put a box which is about 15cm in height under the D board to fix it.
(Please disconnect the CN 701 first.)
D board
Box
1-3. A1 BOARD REMOVAL
1-4. A1 BOARD AND US BOARD REMOVAL
Two screws
(+BVTT 4 x 6)
(+BVTT 4 x 6)
2 Video block assembly
11 Screw (+BVTT 4 x 6)
13 Five screws
(+BVTT 3 x 8)
14 USB case
15 US board
12 USB block assembly
3 Four screws
(+BVTP 3 x 8)
Screw
(+BVTP 3 X 10)
(+BVTP 3 X 10)
9 Video case
8 Input/out
terminal board assembly
[NH]
[NH]
CN315
CN313
CN2601
1
6
Two screws
(+BVTP 3 X 8) [NH]
(+BVTP 3 X 8) [NH]
7
5 Two screws (HEX)
10 A1 board
4 Video shield
— 9 —
CPD-G420
1 A1 board
CN315
CN318
GND
GND
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