General RF troubleshootingGeneral RF troubleshootingMost RF semiconductors are static discharge sensitiveTwo types of measurements are used in the following. It will be specified if the measurement type is "RF" or"LF".• RF measurements are done with a Spectrum Analyzer and a high-frequency 500 ohm passive probe, forexample HP54006A. (Note that when measuring with the 500ohm probe the signal will be around 20dBattenuated. The values in the following will have these 20dB subtracted and represent the real value seenon the spectrum analyzer). Note that the testing have some losses which must be taken into considerationwhen calibrating the test system.• LF (Low frequency) and DC measurements should be done with a 10:1 probe and an oscilloscope. The probeused in the following is 10Mohm/8pF passive probe. If using another probe then bear in mind that thevoltages displayed may be slightly different. Always make sure the measurement set-up is calibrated whenmeasuring RF parameters on the antenna pad. Remember to include the loss in the module repair jig whenrealigning the phone.So ESD protection must be applied during repair (ground straps and ESD soldering irons). Mjoelner and Bifrostare moisture sensitive so parts must be pre-baked prior to soldering. Apart from key-components describedin this document there are a lot of discrete components (resistors, inductors and capacitors) for whichtroubleshooting is done by checking if soldering of the component is done properly and checking if thecomponent is missing from PWB. Capacitors can be checked for short-circuiting and resistors for value bymeans of an ohmmeter, but be aware in-circuit measurements should be evaluated carefully. In the followingboth the name EGSM and GSM850 will be used for the lower band and both PCN and GSM1900 will be usedfor the upper band.RF key componentsFigure 29 RF key components on PWBN7600 PMB3258 RF ICN7700 FEM (PA and antenna switch)Z7602 EGSM 850/900 RX SAW filterZ7600 DCS 1800/PCS1900 RX SAW filterRM-298; RM-299RF Troubleshooting InstructionsIssue 1 COMPANY CONFIDENTIAL Page 4 –7Copyright © 2007 Nokia. All rights reserved.
