Service manual

30
LC-20B8U-S
LC-20B9U-S
LC-20B9U-SM
TROUBLE SHOOTING TABLE (Continued)
Check the secondary
load of T7001.
Is pin (10) of IC7002
and IC7001 at "H"?
Check the load of
IC7002 and IC7001 and
its peripheral circuits.
Is the primary
oscillation wave of
T7001 as specified?
Are the secondary
outputs of T7001 +5V, -
12V, +35V and +9V?
Is there DC 12V input at
T7001 and pin (8) of
IC7301?
Is the output voltage of
IC7002 and IC7001 as
specified?
Check the load of IC701
thru IC703.
Check T7701, IC7701
and their peripheral
circuits.
Check the primary side
of T7001, IC7301 and
its peripheral circuits.
Disconnect F7701. Is
the load short-circuited?
Is pin (187) of IC801 at
"H" or pulse?
Check the line in
question, IC801 and its
peripheral circuits.
Check the primary side
of T7001, Q7001 and
its peripheral circuits.
Check pin (72) of
IC2001, pin (12) of
SC2004 and pin (12)
of P7702.
No video and audio output (no power) No fluorescent lamp light-up
No No
No
No
No
No
No
Are Q6719-Q6724 free
from short-circuit?
Check Q6719-Q6724 and
their peripheral part.
No
No
Are F7701 as specified?
Replace F7701.
Is F6701 normal?
Replace F6701.
Yes
Replace and check the
fluorescent lamp.
Yes
Yes
Is the oscillation
waveform of the primary
side of T6701-T6712
normal?
Check the peripheral
parts of Q6719-Q6724
and the connecting cable.
No
Yes
Yes
Yes
Yes
Yes Yes
Yes Yes
Check the microprocessor's adjustment process menu for wrong settings.