Sony KV-20S90, KV-21SE43C service manual Self-Diagnostic Screen Display, Self Diagnostic

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 confirmation.

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

Note that this differs from entering the Service Mode (Sound Volume

+

).

Self-Diagnostic Screen Display

SELF DIAGNOSTIC

2:000

3:N/A

4:000

5:001

101:N/A

Numeral “0” means that no fault was detected. Numeral “1” means a fault was detected one time only.

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

		IC301
	Y/CHROMA JUNGLE
FROM
CRT	21 IK IN
FROM	18 HP/PROTECT
IC521
PIN 7		SDA 35

IC541	IC001		IC003
V. OUT	SYSTEM		MEMORY
	IO-BDAT	36	5 BDA
REF 3	17 I-PROT
	O-LED	18
	37		DISPLAY
	IO-SDAT

+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 Deflection 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).

— 7 —