Sony KV-20S90 Service Manual ▷ View online
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KV-20S90 / 21SE43C
Detected Symptoms
SELF-DIAGNOSTIC FUNCTION
*If a +B overcurrent is detected, stoppage of the vertical defl ection is detected simultaneously. The symptom that is diagnosed fi rst by the
mircrocontroller is displayed on the screen.
**Refer to Screen (G2) Adjustments in Section 2-4. of this manual.
mircrocontroller is displayed on the screen.
**Refer to Screen (G2) Adjustments in Section 2-4. of this manual.
Display of Standby/Timer LED Flash Count
2 times
4 times
5 times
LED ON 0.3 sec.
LED OFF 0.3 sec.
LED OFF
3 sec.
Diagnostic Item
Flash Count*
+B Overcurrent
2 times
Vertical Defl ection Stopped 4 times
White Balance Failure
5 times
*One fl ash count is not used for self-diagnostic.
Stopping the Standby/Timer LED Flash
Turn off the power switch on the TV main unit or unplug the power cord from the outlet to stop the STANDBY/TIMER LAMP from fl ashing.
Turn off the power switch on the TV main unit or unplug the power cord from the outlet to stop the STANDBY/TIMER LAMP from fl ashing.
Self Diagnosis
Supported model
Standby/Timer LED
The units in this manual contain a self-diagnostic function. If an error occurs, the STANDBY/TIMER LED will automatically begin to fl ash. The number
of times the LED fl ashes translates to a probable source of the problem. A defi nition of the STANDBY/TIMER LED fl ash indicators is listed in the
instruction manual for the user’s knowledge and reference. If an error symptom cannot be reproduced, the Remote Commander can be used to review
the failure occurrence data stored in memory to reveal past problems and how often these problems occur.
of times the LED fl ashes translates to a probable source of the problem. A defi nition of the STANDBY/TIMER LED fl ash indicators is listed in the
instruction manual for the user’s knowledge and reference. If an error symptom cannot be reproduced, the Remote Commander can be used to review
the failure occurrence data stored in memory to reveal past problems and how often these problems occur.
Diagnostic Test Indicators
When an error occurs, the STANDBY/TIMER LED will fl ash a set number of times to indicate the possible cause of the problem. If there is more than
one error, the LED will identify the fi rst of the problem areas.
Results for all of the following diagnostic items are displayed on screen. No error has occurred if the screen displays a “0”.
When an error occurs, the STANDBY/TIMER LED will fl ash a set number of times to indicate the possible cause of the problem. If there is more than
one error, the LED will identify the fi rst of the problem areas.
Results for all of the following diagnostic items are displayed on screen. No error has occurred if the screen displays a “0”.
Power does not turn on
+B overcurrent (OCP)*
Vertical Defl ection
Stopped
Stopped
White Balance failure
(not balanced)
(not balanced)
Does not light
2 times
4 times
5 times
2:0 or 2:1
4:0 or 4:1
5:0 or 5:1
• Power cord is not plugged in.
• Fuse is burned out (F601). (A Board)
• Fuse is burned out (F601). (A Board)
• H.OUT (Q502) is shorted.(A Board)
• IC1751 (C Board) is shorted.
• IC1751 (C Board) is shorted.
• +13V is not supplied. (A Board)
• IC541 is faulty. (A Board)
• IC541 is faulty. (A Board)
• Video OUT (Q392 to Q394) is faulty.
(A Board)
• IC301 is faulty. (A Board)
• Screen (G2) is improperly
• Screen (G2) is improperly
No. of times
STANDBY/ TIMER
lamp fl ashes
Diagnostic Item
Description
Self-Diagnositc
Display/
Diagnostic Result
Probable Cause Location
• Power does not come on.
• No power is supplied to the TV.
• AC Power supply is faulty.
• No power is supplied to the TV.
• AC Power supply is faulty.
• Power does not come on.
• Load on power line is shorted.
• Load on power line is shorted.
• Has entered standby state after horizontal raster.
• Vertical defl ection pulse is stopped.
• Power line is shorted or power supply is stopped.
• Vertical defl ection pulse is stopped.
• Power line is shorted or power supply is stopped.
• No raster is generated.
• CRT Cathode current detection reference pulse
• CRT Cathode current detection reference pulse
output is small.
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KV-20S90 / 21SE43C
Self-Diagnostic Screen Display
For errors with symptoms such as “power sometimes shuts off” or “screen sometimes goes out” that cannot be confi rmed, it is possible to bring up
past occurrences of failure on the screen for confi rmation.
For errors with symptoms such as “power sometimes shuts off” or “screen sometimes goes out” that cannot be confi rmed, it is possible to bring up
past occurrences of failure on the screen for confi rmation.
To Bring Up Screen Test
In standby mode, press buttons on the Remote Commander sequentially, in rapid succession, as shown below:
In standby mode, press buttons on the Remote Commander sequentially, in rapid succession, as shown below:
Display
Channel 5
Sound Volume -
Power ON
Self-Diagnostic Screen Display
Numeral “0” means that no fault was detected.
Numeral “1” means a fault was detected one time only.
Numeral “1” means a fault was detected one time only.
SELF DIAGNOSTIC
2: 000
2: 000
3: N/A
4: 000
5: 001
101: N/A
Handling of Self-Diagnostic Screen Display
Since the diagnostic results displayed on the screen are not automatically cleared, always check the self-diagnostic screen during repairs. When you
have completed the repairs, clear the result display to “0”.
Unless the result display is cleared to “0”, the self-diagnostic function will not be able to detect subsequent faults after completion of the repairs.
Since the diagnostic results displayed on the screen are not automatically cleared, always check the self-diagnostic screen during repairs. When you
have completed the repairs, clear the result display to “0”.
Unless the result display is cleared to “0”, the self-diagnostic function will not be able to detect subsequent faults after completion of the repairs.
Clearing the Result Display
To clear the result display to “0”, press buttons on the Remote Commander sequentially when the diagnostic screen is displayed, as shown below:
To clear the result display to “0”, press buttons on the Remote Commander sequentially when the diagnostic screen is displayed, as shown below:
Channel 8
ENTER
Quitting the Self-Diagnostic Screen
To quit the entire self-diagnostic screen, turn off the power switch on the Remote Commander or the main unit.
To quit the entire self-diagnostic screen, turn off the power switch on the Remote Commander or the main unit.
Self-Diagnostic Circuit
+B overcurrent (OCP)
Occurs when an overcurrent on the +B (115V) line is detected by pin 18 of IC301. If the voltage of pin 18 of IC301 is less than 1V when V.SYNC is more
than seven verticals in a period, the unit will automatically turn off.
Vertical Defl ection Stopped
Occurs when an absence of the vertical defl ection pulse is detected by pin 17 of IC001. Power supply will shut down when waveform interval
exceeds 2 seconds.
White Balance Failure
If the RGB levels* do not balance within 2 seconds after the power is turned on, this error will be detected by IC301. TV will stay on, but there
will be no picture.
Occurs when an overcurrent on the +B (115V) line is detected by pin 18 of IC301. If the voltage of pin 18 of IC301 is less than 1V when V.SYNC is more
than seven verticals in a period, the unit will automatically turn off.
Vertical Defl ection Stopped
Occurs when an absence of the vertical defl ection pulse is detected by pin 17 of IC001. Power supply will shut down when waveform interval
exceeds 2 seconds.
White Balance Failure
If the RGB levels* do not balance within 2 seconds after the power is turned on, this error will be detected by IC301. TV will stay on, but there
will be no picture.
*(Refers to the RGB levels of the AKB detection Ref pulse that detects 1K).
Note that this differs from entering the Service Mode (Sound Volume + ).
IC301
Y/CHROMA JUNGLE
IC541
V. OUT
IC001
SYSTEM
IC003
MEMORY
IK IN
FROM
CRT
HP/PROTECT
SDA
FROM
IC521
PIN 7
18
IO-SDAT
O-LED
REF
I-PROT
IO-BDAT
BDA
DISPLAY
21
35
3
17
37
18
36
5
— 8 —
KV-20S90 / 21SE43C
1-1. REAR COVER REMOVAL
1-2. CHASSIS ASSEMBLY REMOVAL
1-3. SERVICE POSITION
SECTION 1: DISASSEMBLY
Screw +BVTP 4x16
Chassis Assembly
C Board
A Board
Screw +BVTP 4x16
2 Screws +BVTP 4x16
Claw
Rear Cover
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KV-20S90 / 21SE43C
1. Discharge the anode of the CRT and remove the anode cap.
2. Unplug all interconnecting leads from the defl ection yoke, neck
assembly, degaussing coils and CRT grounding strap.
3. Remove the C Board from the CRT.
4. Remove the chassis assembly.
5. Loosen the neck assembly fi xing screw and remove.
6. Loosen the defl ection yoke fi xing screw and remove.
7. Place the set with the CRT face down on a cushion and remove
the degaussing coil holders.
8. Remove the degaussing coils.
9. Remove the CRT grounding strap and spring tension devices.
10. Unscrew the four CRT fi xing screws [located on each CRT
corner] and remove the CRT [Take care not to handle the CRT
by the neck].
by the neck].
1-4. PICTURE TUBE REMOVAL
WARNING: BEFORE REMOVING THE ANODE CAP
High voltage remains in the CRT even after the power is disconnected. To avoid electric shock,
discharge CRT before attempting to remove the anode cap. Short between anode and CRT
coated earth ground strap.
High voltage remains in the CRT even after the power is disconnected. To avoid electric shock,
discharge CRT before attempting to remove the anode cap. Short between anode and CRT
coated earth ground strap.
Coated
Earth
Ground
Strap
Earth
Ground
Strap
ANODE CAP REMOVAL PROCEDURE
WARNING: High voltage remains in the CRT even after the power is disconnected. To avoid electric shock, discharge CRT before attempting to
remove the anode cap. Short between anode and coated earth ground strap of CRT.
NOTE: After removing the anode cap, short circuit the anode of the picture tube and the anode cap to either the metal chassis, CRT shield, or
carbon painted on the CRT.
remove the anode cap. Short between anode and coated earth ground strap of CRT.
NOTE: After removing the anode cap, short circuit the anode of the picture tube and the anode cap to either the metal chassis, CRT shield, or
carbon painted on the CRT.
HOW TO HANDLE AN ANODE CAP
1. Do not use sharp objects which may cause damage to the surface of the anode
cap.
2. To avoid damaging the anode cap, do not squeeze the rubber covering too hard.
A material fi tting called a shatter-hook terminal is built into the rubber.
3. Do not force turn the foot of the rubber cover. This may cause the shatter-hook
terminal to protrude and damage the rubber.
10
1
9
8
7
6
5
4
3
2
a
b
Anode Button
c
Turn up one side of the rubber cap in
the direction indicated by arrow a .
the direction indicated by arrow a .
1
Use your thumb to pull the rubber
cap fi rmly in the direction indicated
by arrow b .
cap fi rmly in the direction indicated
by arrow b .
2
When one side of the rubber cap separates from
the anode button, the anode cap can be removed
by turning the rubber cap and pulling it in the
direction of arrow c .
the anode button, the anode cap can be removed
by turning the rubber cap and pulling it in the
direction of arrow c .
3
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