NOKIA NHM5-029 free download

File name NHM5-029.PDF

CONFIDENTIAL 1 (3) Nokia Mobile Phones Service Bulletin No. SB-029/25.04.01 Technical Support, Europe & Africa NHM-5 BROKEN C508 If the end user complains of following symptoms: - dropped calls - no service - poor downlink audio - poor performance in weak fields etc and then in service point following symptoms can be found: - the phone may have difficulties to make location update/go in to service on GSM tester, if the RF level is low - RX sensitivity is very poor - the BER can be alternating between very high % and 0%, if RF level is below -65dBm - the problem can be seen in both GSM900 and GSM1800 bands it is likely that C508 (4x100 nF capacitor array 0508) is broken and needs to be changed. ITEM CODE DESCRIPTION C508 2315105 CHIP ARRAY X5R 4X100N M 10V Verification It is simple to verify if broken C508 causes the problem by measuring the RX I and Q signals with oscilloscope. Oscilloscope should be set to 1ms/div and 500mV/div and appropriate Probe should be used. Note: It is not recommended to use a simple Voltmeter to do this verification. Test points The RX I and Q signals can be measured on PWB in two ways, on the topside (component side) and on the bottom side (keypad side) NHM-5 SB-029 CONFIDENTIAL 2 (3) Top side Bottom side The two vias highlighted in above picture can also be measured from the bottom side of the PWB. (In this case it is not necessary to remove the shielding can lid, but the lightguide can not be used) Measurement procedure 1. Place the PWB in MJS-19 Module Repair Jig 2. Turn the phone on and set it to local mode with WinTesla 3. Select RX BURST mode in RF controls menu. No external signal is needed 4. Measure RX I and Q signals with Oscilloscope NHM-5 SB-029 CONFIDENTIAL 3 (3) Measurement reference In case that C508 is not faulty both RX I and Q signals should look like the following picture In case that either RX I or Q or both signals looks like the below picture, C508 is broken and should be replaced. NHM-5 SB-029