TFE-4/RV-1 Company Confidential
TF4 Technical Information Nokia Customer Care
Page 8b-52 Copyright © 2005 Nokia Corporation. Issue 2.0 Mar/2005
Company Confidential
Fault finding chart for the receiver
The phone layout does not have dedicated test points for the analogue differential RX I
and Q signals (RXIINP, RXIINN, RXQINP, RXQINN) from Mjoelner RF ASIC to UEM. The BB
part is used to measure those signals by means of RSSI reading. It is assumed that cor-
rect calibration of RSSI reading has been carried out. RSSIreading [dBm] = 20log(U
BB
)
+ AGC
calibrated
Therefore, don’t calibrate a defective phone before the phone error has been found.
When a defective phone has been calibrated, a possible error in RX front end might be
masked. In that case one can have a reasonable RSSI reading, although the front end
shows excessive losses. To rule this out do the following:
Check if AGC calibration is within limits
Check if SNR reading is OK.
Use an Oscilloscope to check levels of “RXIINN” and “RXQINN”.
If RX and TX path are faulty it has to be checked that synthesizer is working. If it does,
then check path from RF connector X602 to antenna switch Z601 (see RX fault finding
"Check RXTX switch")
Rx Signal paths
The signal paths of the receiver are shown in following block diagram. Note that the pic-
RX Fault finding
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