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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
T
Apply -80dBm signal
from Generator
to Antenna Connector
phone: local, burst mode
Rx chain
functional
RX calibration
Yes
No
EGSM,
PCS, PCN
RSSI reading
-80dBm
all bands
?
Yes
No
Calibrtion.
witin
limits
?
Yes
No
EGSM,
PCS, PCN
SNR measurement
all bands
o.k.
?
Apply -92dBm signal
from Generator
to Antenna Connector
phone: local, burst mode
RSSI
and SNR
wrong in all 3
bands
?
No
Change generator level
to -55dBm
phone: local,
continous mode
SA
Z601
EGSMout
-76dBm
Yes
No
SA
Z601
Rx output
(900,1800,1900)
> -75dBm
?
SA
Z601
EGSMout
-76dBm
Yes
No
SA
Z604,Z602,Z603
SAWout
both lines
>-78dBm
?
Change
Z604,Z602,Z603
Check
RxTx Switch
Change
Z601
Yes
SA
Z601
EGSMout
-76dBm
No
Osci:
RF-BB
serial
Interface
o.k.
?
Yes
SA
Z601
EGSMout
-76dBm
No
Osci:
RX I/Q
level
o.k.
?
Change
Mjolner
Yes
BB Error
Check UEM
Check
SAW
SA
Z601
EGSMout
-76dBm
No
Osci:
LNA
base voltage
= 0.8V
?
Change
Mjolner
Check
LNA
SA
Z601
EGSMout
-76dBm
Yes
No
Osci:
LNA bias
(VR6)
=2.8V
?
Check
C620, C632
and
BB (UEM)
Yes
SA
Z601
EGSMout
-76dBm
No
Osci:
RX -BB bias
(VR4)
=2.8V
?
Check
C871
and
BB (UEM)
Check
Bias
Check
Bias
= to be done in all 3 bands
= to be done in
defective band only
= to be done only once
(common for all bands)
BB Error
Check UPP
Make sure that
Synthesiser
is working
Yes
Note: RF levels given in that chart are dependent on RF probe and must be validated with a known good sample
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