Operating instructions

9-2 800/900 Band Troubleshooting Charts
B
Inject RF
into P900
IF Signal
at C601?
Trace IF signal
from C601 to
Q400. Check for
bad XTAL filter.
Q400 & Q401
collector OK? IF
signal is present?
Check for
5V_RX?
Check U8002, U201
A
Before replacing
U600, check U600
voltages; trace IF
signal path.
No
Yes
Yes
Yes
Yes
No
No
RF Signal
at U401?
RF Signal
at C412?
RF Signal
at C406?
RF Signal
at C400?
1
st
LO
locked?
Check FGU
Check T400,
pin 5 of U401
Check filter between
C412 & U401
Check LNA (U400)
Check filter between
C400 & C406
No
No
No
No
Yes
Yes
Yes
Yes
No
Check Harmonic Filter
C902, C904, C905, L901
and L905 and antenna
switches U900, U901
Troubleshooting Flow Chart for Receiver
(Sheet 2 of 2)