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Trouble Sh ooting
A LC502
8. Checking the resolution change IC movement
Is there +3.3V supply on I300 pin 17, 21, 57, 77, 79, 97, 102, 117, 137, 154, 156, 157 and 65.
OK
NG
Is 12MHz clock input to I300 pin 3 at
TTL level?
Proceed "Checking the DC/DC converter circuit" section.
OK
NG
Is 12MHz clock output from X300
at TTL level?
OK
NG
Failure point
Print wire broke between X301 and
I300 pin 3.
Failure point
X300 failure
Is +5.0V supplied to I300 pin 2 at
High level?
OK
NG
Check the output of 5.0V "H" pulse
from I302 pin 6.
OK
NG
Is 5.0V supplied to I302 pin 7?
Failure point
I300 failure
Failure point
Print wire broke between I302 pin 6
and I300 pin 2.
OK
NG
Failure point
I302 failure
Failure point
1) FB319 open
2) Power source