RM-14
Nokia Customer Care
RF Troubleshooting and Manual Tuning
10
COMPANY CONFIDENTIAL
ISSUE 1 11/04
Copyright © 2004 Nokia. All Rights Reserved.
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Tx 900 GMSK troubleshooting
Figure 5:TX 900 GMSK troubleshooting
TX850/900 GMSK troubleshooting
Apply a 50 ohm load at the antenna connector of the jig.
GSM900/ cha. 37 = 897.4 MHz, burst mode power level 10
Spectrum analyzer: RBW = 500 Khz and VBW = 500 kHz,
center = 500 kHz and span = 20 MHz
c) VANT_3 = 2.7 V at C810
b) VANT_2 = 0 V at C809
a) VANT_1 = 2.7 V at C811
Measure Z800 antenna switch control signal voltages
Measure N700 PA supply voltage VBAT at C705
Measure RF level = 20 dBm at antenna pad J124
Note: VPCTRL_G voltage is a function of power level.
b) VTXB_G = 2.7V (C701).
R713 and N700 PA bias voltage.
Measure N700 PA control voltage a) VPCTRL_G = 1.2 V during burst at
Note: DET voltage is a function of power level
Measure N700 PA power detector DET = 850 mV during burst at R701.
NOK
(Z800 pin1)
Measure RF level = +10 dBm at N700 PA output TX_OUT_EGSM
OK
Measure RF level = -13 dBm at N700 PA input (R704 pin1)
Measure RF level = -13 dBm at input of Z700 SAW filter C702
Measure modulator supply voltage VR2 = 2.7 V (C511, both terminals)
Measure voltage of a) TXI at C529 and TXQ at C530,
Txi and TXQ = 500 mVpp min. and 1.4 VDC during burst
Measure a) TXC = 800 mV during burst at R514 and
b) TXP = 1.8 V during burst at J504 .
Note: TXC voltage is a function of power level
Check
baseband.
NOK
NOK
NOK
Check
N500 Helgo.
Check Z700
Tx SAW.
TX 900 GMSK troubleshooting
