NEC VT440 Service Manual page 47

TROUBLESHOOTING
!
Is there a video signal input (sync provided) at Pin 28 (G) of POMI?
NO Check the POMI connector, poor soldering in I/O PWB, and the signal cable.
YES Check IC1001, Q1000, and the peripheral circuits.
@
Is there a vertical sync signal (in positive polarity) at TP3507?
YES
NO
@
Is the input signal for VIDEO or DVD?
YES
NO
#
Is there a vertical sync signal (in positive polarity) at Pin 84 of IC3301?
YES
NO
$
Are there signals at Pin 4 (SOG), Pin 6 (H), and Pin 8 (V) of IC1006?
YES
NO
%
Are there signal inputs at Pin 28 (SOG), Pin 24 (H), and Pin 22 (V) of POMI?
NO Check the POMI connector, poor soldering in I/O PWB, and the signal cable.
YES Check Q1025 to 34, Q1000, Q1013 to 6, and the peripheral circuits.
^
Is there a vertical sync signal (in positive polarity) at Pin 87 of IC3301?
YES
NO
&
Is there a vertical sync signal (in negative polarity) at Pin 5 of IC1104?
YES Check Q1110 to 1 and the peripheral circuits.
NO To
4. No sound generation
1
Are there audio signals at Pins 48 and 56 of IC4100?
YES
NO
2
Is there an audio signal at Pin 9 of IC4100?
YES
NO
3
Is there a signal input at Pin 14 (AUDIO) of POMI?
NO Check the POMI connector, poor soldering in I/O PWB, and the signal cable.
YES Check Q1011, ST connector, and the peripheral circuits.
4-7
Check IC3502 and the peripheral circuits.
^
To .
Check IC3301 and the peripheral circuits.
Check IC1006 and the peripheral circuits.
Check IC3301 and the peripheral circuits.
9
.
Check the speaker, connector, and the peripheral circuits.
Check IC4100, VOL voltage at Pin 28, and the peripheral circuits.