Nokia 6235 Troubleshooting Manual page 42

6235/6235i/6236i (RM-60)
RF Description and Troubleshooting
1900MHz (PCS).
• After the RFA, there is a mixer, and then the signals are separated by CDMA (Cell
and PCS) and AMPS.
For example, if there is no IF frequency (128.1MHz) check both Cell and PCS. If
only one has 128.1MHz at L753, ensure that IF_SEL is working. If it is, then
replace the N750 due to a bad RFA.
If Cell and AMPS are working but PCS is not, look at the band select line and the
PCS LNA before replacing the N7160.
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
Page 42
Figure 41: N7160 receiver
©2005 Nokia Corporation
Company Confidential Issue 1 04/2005