KV-25FS12 - Sony TV Service Manual (repair manual). Page 7

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KV-25FS12 / 25FS12C
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.
To Bring Up Screen Test
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.
SELF DIAGNOSTIC
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.
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
+B overcurrent (OCP) 
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. 
I-Prot 
Occurs when an absence of the vertical defl ection pulse is detected by pin 17 of IC1001 (MB Board). Power supply will shut down when waveform 
interval exceeds 2 seconds. 
IK (AKB) 
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).
Note that this differs from entering the Service Mode (Sound Volume  +  ).
MB BOARD
IC1301
Y/CHROMA JUNGLE
A BOARD
IC502
V. OUT
MB BOARD
IC1001
SYSTEM
MB BOARD
IC1003
MEMORY
IK IN
FROM
CB BOARD
IC702 PIN 5
HP/PROTECT
SDA
A BOARD
FROM
IC501
PIN 3
18
IO-SDAT
O-LED
REF
I-Prot
IO-BDAT
BDA
DISPLAY
21
35
3
17
37
18
36
5
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Display

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