Motorola 38C V100, Service Manual

Page: 36 / 83

MOTOROLA CONFIDENTIAL - PROPRIETARY
32 November 20, 2000 6881036B20
Troubleshooting Product Family 38C
Figure 16. Device Will Not Receive DCS/PCS Signals
In most cases, a reference board can be
used to compare signals.
START
1. Connect an RF signal generator
to EXT CONN TP1 . Set generator
(or DCS BCCH #700) as follows:
Frequency: 1842.8 MHz (DCS)
Level: -30 dBm
2. Place UUT into manual test
mode, then enter 9820# (change
DCS mode), 450700# (DCS
ARFCN).
YES
Is fault PCS only?
YES
RVCO_PCS and
RVCO_DCS are present on
U400 Pin 6 and Pin 4 ?
YES
Check FL1400 then U150 and U151 .
See Note 1
Check FL2400 then U150 and U151 .
See Note 1
See "L" Figure 24. "Receiver VCO Band
Select".
1960 MHz (PCS) signals
are present on C1402 ?
YES
Check U400 .
See Note 1
Correct signal is present on
C1405 ?
YES
RX275_DPCS is present on collector of
Q1400 ?
See Note 1
Correct signal is present on
C2452 ?
YES
Check FL1401 .
See Note 1
400 MHz signal is present
on C460 ?
YES
RX275_DPCS is present on
Q450 Pin 3
(approximately 1.2V)?
See Note 1
Check for
intermittent faults
then end.
Note 1: Check components for correct
orientation, cold solder joints, physical
damage, and functionallity.
NO
NO
NO
NO
NO
NO
Check Q450
.
See "P" Figure 17. "No
Receiver Control Matrix".
NO
YES
See "P" Figure 17. "No
Receiver Control Matrix".
NO
Check Q1400 .
YES
Is fault DCS only?
1. Set generator (or PCS BCCH #661) as follows:
Frequency: 1960 MHz (PCS)
Level: -30 dBm
Enter 9822# (Change PCS mode), 450661#
(change PCS ARFCN)
NO