Sony TRINITRON KV-20FS12 Service Manual page 6

KV-20FS12/20FV12/21FE12/A/C/21FM12/21FV12/C
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.
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:
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.
Self-Diagnostic Circuit
Y/CHROMA JUNGLE
FROM
21 IK IN
CRT
A BOARD
FROM
18 HP/PROTECT
IC502
PIN 7
+B overcurrent (OCP)
Vertical deflection stopped
White balance failure
MB BOARD A BOARD
IC1301 IC507
V. OUT
REF
SDA 35
Occurs when an overcurrent on the +B (135V) line is detected by pin 18 of IC1301 (MB Board).
If the voltage of pin 18 of IC1301 (MB Board) is less than 1V when V.SYNC is more than seven
verticals in a period, the unit will automatically turn off.
Occurs when an absence of the vertical deflection pulse is detected by pin 17 of IC1001 (MB
Board). Power supply will shut down when waveform interval exceeds 2 seconds.
If the RGB levels* do not balance within 2 seconds after the power is turned on, this error will be
detected by IC1301 (MB Board). TV will stay on, but there will be no picture.
*(Refers to the RGB levels of the AKB detection Ref pulse that detects 1K).
MB BOARD
IC1001
SYSTEM
IO-BDAT
3 17 I-PROT
O-LED
37 IO-SDAT
— 6 —
MB BOARD
IC1003
MEMORY
36 5 B-DAT
18
DISPLAY