User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 41
Original 11/97
•Check the voltage drop across R16 at the RX_ICT line, placing one probe
on either side of this resistor. The voltage drop should be approx 37 mV.
If not, first ensure that the phone is in the CDMA Troubleshooting Mode. Ensure that
the –75 dBm 881. 62 MHz CW signal is fed into the receiver. If fault is found then
continue with the remaining receiver DC Voltage checks. After doing so there is still
no problem, refer to the AGC Troubleshooting Manual. Perform the DC Voltage
checks on that module to determine if there is a problem with the AGC circuitry.
•Check the CDMA IF LNA V7 and V8
The voltage on the collector of V7, pin 1 should be approximately 1.38 V.
The voltage on the base of V7, pin 3 should be approximately 1.33 V.
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Inspect V8, V7,
L5, R19, R20. Ensure that VRXDM is approximately 4.50 V at R21.
The voltage on the emitter of V7, pin 2 should be approximately .60 V.
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Inspect V7, and
L6.
•Check the 1st IF gain stage V9
The voltage on the collector, pin 1 should be approximately 3.50 V.
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Inspect V10,
V9, R22, R23, Z3. Ensure that VRXDM is approximately 4.50 V at R23
The voltage on the base, pin 3 should be approximately 1.85 V.
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Inspect V9, V4,
L13, L11, R4, R5, R13, R14, R15, and R24. Ensure VRXDM is about 4.50 V at R21.
See that VRXM is at about 4.40 V at R13, and VRXAM is about 1.15 V at R14
The voltage on the emitter, pins 2 and 4 should be approximately 1.12 V.
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Inspect V9,
L14, R25, and R28.
•Check the LNA, V12
The voltage on the collector should be approximately 3.90 V
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Ensure VRXM
is at about 4.40 V at R833. Inspect V11, V12, L20, R33, R34, R38, and R833.
The voltage on the base should be 1.0 V
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Ensure VRXM
is at about 4.40 V at R833. Inspect V11, V12, L21, L22, R33, R35, and R833.
•Check the control voltages on the RF Gain Switches N701 and N702.
Pin 1 on both should be approximately 3.80 V.
If not, confirm that the phone is in the CDMA Troubleshooting Mode. Ensure VRXM
is at about 4.40 V at R832. Inspect N701, N702, V1, V708, R775, R777, R779,
R781, R783, R803, R830, R831, and R832.