Nokia 3155 Rf Description And Troubleshooting page 44

3155/3155i (RM-41), 3152 (RM-61)
RF Description and Troubleshooting
There are two common explanations for an N7160 failure consisting of high
current in Local Mode with just the Rx turned on:
• No presence of an LO signal
• Input impedance drop is shorting out one of the DC supply pins to the chip
IMPORTANT: You must check for both conditions before replacing the chip. If you
have no LO signal, refer to
voltage drop on one of the supply pins, then replace the N7160.
Condition: Local Mode, Set
Rx Only in RF Main Mode
Good mobile terminal
No UHF LO signal present
Pin 13 shorted
Page 44
Cell
RFA
IFAs
LO
PCS
Buffer
RFA
Figure 37: N7160 Receiver
"UHF Synthesizer" on page 52. If you have a significant supply
Table 12: N7160 Conditions and Supply Currents
©2005 Nokia Corporation
Cell
LNA
PCS
LNA
Supply Current
(From Power Supply)
100mA
254mA
255mA
Company Confidential ISSUE 1 07/2005