NEC -FA150ATUA Service Manual page 43

14.4 Check the USB IC
Is 5V supplied to I201 pin 1 ?
NG
Does it have the High level
(More than 4.75V ) from I201
pin 9,10,12
NG
Does X201 oscillate (6 MHz) ?
NG
Isn't I201 pin 15 fixed on the
High level ( more than 2.0V ) ?
and isn't pin14 fixed on the
Low level ( less than 0.8v ) ?
NG
Does it have the High Level ( more than
4.75V ) from I201 Pin 9.
NG
Failure point
I201 failure
Trouble Shooting
Proceed section 14.5 " Check the power supply ".
Proceed section 14.5 " Check the power supply ".
Does the output of X201 satisfy a threshold level
( High:more than 4.75V,Low:less than 0.8V) ?
NG
OK
Failure point
I201 failure
Failure point
Faulty operation of the host PC.
Does R234 open ?
NG
OK
Does Q205 short ?
NG
OK
Does Q201 short ?
NG
OK
Failure point
Faulty operation of the over current protection function.
NEC-FA150ATUA
Failure point
X201 failure
Failure point
R234 failure
Failure point
Q205 failure
Failure point
Q201 failure