37
XG-P20XU
XG-P20XE
XG-P20XD
TROUBLE SHOOTING TABLE
(Continued)
Checking the video unit circuit
Yes
No
Check the IC5555 selector switch,
terminal voltage and input circuit.
Yes
No
Is there video signal input at pins
(76) and (88) of IC4502?
Check the low-pass and buffer
circuits of Q4501,Q4502,and
Q4508,Q4509.
Yes
No
Are there signal outputs at pins (83)
and (84) of IC4502?
Check IC4502,IC4503 and their
peripheral circuits (bias).
Yes
No
Check the buffer circuits of Q4503
thru Q4504. Is the signal as
specified?
Check IC4501,IC4311and their
peripheral circuits.
(Go to "Checking the output
PWB unit".)
Is there video signal output at P401
pin (9).
Check Q4503 thru Q4504 and their
peripheral circuits.
Checking the video system
Yes
No
Go to "Lamp fails to light-up".
Yes
No
Is specified voltage fed to EA
connectors?
Check the power circuit and its parts.
Yes
No
Are there signal inputs at pins (9),
(19) and (21) of SC401?
Are there signals at pin (7) of IC5555?
Are there signal outputs at pins
(1),(12) and (14) of SC4303?
No
Check the IC5555 and its
peripheral circuits.
Yes
Check SC4303,P4303 and
their peripheral circuits.
(Go to "Checking the output
PWB unit".)
No
Check IC4311, IC4502,
IC4501and their peripheral
circuits.
Is the lamp on?
