Sony KE-42XS910 Service Manual ▷ View online
5
KE-42XS910
KE-42XS910
WARNINGS AND CAUTIONS
CAUTION
Short circuit the anode of the picture tube and the anode cap to the metal chassis, CRT shield, or carbon painted on the CRT, after
removing the anode.
removing the anode.
WARNING!!
An isolation transformer should be used during any service to avoid possible shock hazard, because of live chassis. The chassis of
this receiver is directly connected to the AC power line.
this receiver is directly connected to the AC power line.
!
SAFETY-RELATED COMPONENT WARNING!!
Components identifi ed by shading and ! mark on the schematic diagrams, exploded views, and in the parts list are critical for safe
operation. Replace these components with Sony parts whose part numbers appear as shown in this manual or in supplements
published by Sony. Circuit adjustments that are critical for safe operation are identifi ed in this manual. Follow these procedures
whenever critical components are replaced or improper operation is suspected.
operation. Replace these components with Sony parts whose part numbers appear as shown in this manual or in supplements
published by Sony. Circuit adjustments that are critical for safe operation are identifi ed in this manual. Follow these procedures
whenever critical components are replaced or improper operation is suspected.
6
KE-42XS910
KE-42XS910
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.
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.
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.
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).
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).
To Exposed Metal
Parts on Set
Parts on Set
0.15 F
Earth Ground
AC
Voltmeter
(0.75V)
Voltmeter
(0.75V)
Trouble Light
AC Outlet Box
Ohmmeter
Cold-water Pipe
Figure A. Using an AC voltmeter to check AC leakage.
Figure B. Checking for earth ground.
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KE-42XS910
KE-42XS910
1-1. REAR COVER REMOVAL
SECTION 1: DISASSEMBLY
Six screws
(+BVTP 4x16)
Four screws
(+BVTP 4x16)
Four screws
(+BVTP 4x16)
Six screws
(+PSW 3x6)
Two screws
(+PSW 3x6)
Stand Assy
Speaker cover (R) Assy
Six screws
(+PSW 4x10)
Two screws
(+PSW 5M) (Stand)
Two screws
(+PSW 5M) (Stand)
Speaker cover (L) Assy
Three screws
(+PSW 5x10)
Three screws
(+PSW 5x10)
Four screws
(+PSW 3x6)
Four screws
(+PSW 3x6)
Rear cover
1
1
2
3
9
5
6
6
6
5
8
8
7
5
6
4
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KE-42XS910
KE-42XS910
1-2. A BOARD REMOVAL
DM Block Assy
Four screws
(+PSW 3x6)
Four screws
(+PSW 3x6)
A board
Two screws
(+PSW 3x6)
2
1
3
4
