Motorola 38C V100 Service Manual page 35

Level 3 Service Manual
START
1. Connect an RF signal generator
to EXT CONN TP1. Set generator
(or GSM BCCH #62) as follows:
Frequency: 947.4 MHz
Level: -30 dBm
2. Place unit under test (UUT)
into manual test mode, then enter
the following key sequences:
9823# (change GSM/DCS mode)
450062# (GSM ARFCN)
Is fault GSM only?
YES
947.4 MHz signal present on
output of FL400?
YES
Correct signal present on
C405?
YES
Correct signal present on
C453?
YES
Correct signal present on
C460 (400 MHz)?
YES
Check for
intermittent faults
then end.
Figure 15. Device Will Not Receive GSM Signals
6881036B20
NO
Check (in order): FL400, U150,
NO
and U151.
See Note 1
RX275_GSM signal present on
collector of Q400?
NO
No: See "P" Figure 17. "No
Receiver Control Matrix"
Yes: Check Q400
See Note 1
Check FL401 .
NO
See Note 1
RX275 signal present on Q450
Pin 1 and RX275_GSM on
NO
L450?
No: See "P" Figure 17. "No
Receiver Control Matrix"
Yes: Check Q450
See Note 1
MOTOROLA CONFIDENTIAL - PROPRIETARY
November 20, 2000
In most cases, a reference board can be
used to compare signals.
NO
RX_VCO signal (1347.4
MHz) is present on C2456?
YES
NO
400 MHz signal present on
C460?
YES
NO
400 MHz signal present at
C480?
YES
NO
400 MHz signal present on
C481?
YES
Check (in order)
U200 and U800.
See Note 1
Note 1: Check components for correct
orientation, cold solder joints, physical
damage, and functionallity.
Troubleshooting
See "Q" Figure 18.
"No Receive VCO".
RX275 signal present
on Q450 Pin 1 and
RX275_GSM on L450?
No: See "P" Figure 17.
"No Receiver Control
Matrix"
Yes: Check Q450
See Note 1
Check FL457 .
See Note 1
Check Q480 .
See Note 1
31