General Instructions for Gsm Rx Troubleshooting

Connect the phone to a PC with the module repair jig.

Start Phoenix and establish connection to the phone Select File. Select Scan for Product Ctrl-R Select Maintenance, Testing and RF Controls

Select:

Band: GSM1800

Active Unit: RX

Operation Mode: Continuous

Rx/Tx Channel: 700

The setup should now look like this:

,RF Controls

Band: I GSM 1800 jJ Active Unit: |F!x Operation Mode:[Continuous Flx/Tx Channel: [TOO 1842.800000 Monitor Channel:[700 1842.800000 AGC: 19: FEG_0N + DTGSJDN + BB_12 = VGain_42 jj] AFC: 13050

Help

Fault Finding Chart for GSM1800 Receiver

Figure 10: GSM1800 receiver fault finding chart

Apply -55 dBm 1842.8 MHz, offset

67.71 kHz from generator to antenna connector yes

Oscilloscope at RX I/Q

signal 408 mVpp DC offset 1.33 V freq. 67.71 kHz yes

PCN chain functional

Oscilloscope at RX I/Q

signal 408 mVpp DC offset 1.33 V freq. 67.71 kHz

Spectrum analyzer Check signal after inductors L611 and L601 -65 dBm

no

Check inductors

L611, L601

|yes

Oscilloscope VRX2.7V

no

Check Base band

check Mjoelner serial interface

By measuring with an oscilloscope at RXIP or RXQP on a working GSM 900 receiver this picture should be seen.

Signal amplitude peak-peak 588 mV

DC offset 1.33 V

Figure 11: RX1800 I/Q signal waveform

i

Ï

■j

«iill 200mV E',,|

M|4.00jiS A| Chi I 1.36 V

Chi Mean 1.33 V

Chi Freq 69.58kHz

Chi Pk-Pk 588mV

Chi Mean 1.33 V

Chi Freq 69.58kHz

Chi Pk-Pk 588mV

30 Nov 2001 02:20:34

Measurement points in the receiver

Figure 12: RX measurements point at the RX/TX Switch - Z700

Figure 12: RX measurements point at the RX/TX Switch - Z700

Figure 13: Measurements points at the RX-Filters - Z601/Z602

RX900 Mjoelner input INML _L602_

RX900 Mjoelner input INPL _L603

RX900

Z602

RX900 SAW filter unbal input _Z602_

RX1800 Mjoelner input INMM L611

RX900 Mjoelner input INPM L601

RX900 Mjoelner input INPL _L603

RX1800 Mjoelner input INMM L611

RX1800 SAW filter bal output Z601

RX1800 SAW filter unbal input Z601

Figure 14: RX I/Q Signals, Baseband shielding can UEM (D200)

Figure 14: RX I/Q Signals, Baseband shielding can UEM (D200)

Was this article helpful?

+1 0

Post a comment