User Guide

ISSUE 1 11/04 COMPANY CONFIDENTIAL 11

RM-14

RF Troubleshooting and Manual Tuning Nokia Customer Care

■ Tx 1800/1900 GMSK troubleshooting

Figure 6:TX 1800/1900 GMSK troubleshooting

Apply a 50 ohm load at the antenna connector of the jig.

GSM1800 ch. 700 = 1747,8 MHz, burst mode power level 5

GSM1900 ch. 661 = 1880,0 MHz, burst mode power level 5

Spectrum analyzer RBW = 500 kHz and VBW = 500 kHz

and span = 20 MHz

c) VANT_3 = 2.7 V at C810

b) VANT_2 = 2.7 V at C809

a) VANT_1 = 0 V at C811

Measure Z800 antenna switch control signal voltages

Measure N700 PA control voltage a) VPCTRL_1800/1900 = 1.0 V during burst at R715

and N700 PA bias voltage

b) VTXB_1800/1900 = 2.7 V (C709).

Note: VPCTRL_1800/1900 voltage is a function of power level.

Measure RF level = 2 dBm at antenna pad J124

Measure N700 PA supply voltage VBAT at C705

Note: DET voltage is a function of power level

Measure N700 PA power detector DET = 810 mV during burst at R701.

NOK

Measure RF level = -3 dBm at N700 PA output TX_OUT_DCS (Z800)

Measure RF level = -10 dBm at N700 PA input R707 pin1

Measure RF level = -15 dBm at input of T700 Tx balun C714

Measure modulator supply voltage VR2 = 2.7 V at L505

Note: TXC voltage is a function of power level

b) TXP = 1.8 V during burst at J504 .

Measure a) TXC = 800 mV during burst at R514 and

Measure voltage of a) TXI at C529 and TXQ at C530,

Txi and TXQ = 500 mVpp min. and 1.4 VDC during burst

TX1800/1900 GMSK troubleshooting

Check

baseband.

NOK

Check

N500 Helgo.

NOK

Check T700

Tx balun.

and N700 PA bias voltage