CONFIDENTIAL
Service & Analysis Center Europe
Training Team
version 1.0 / 05.11.1999 Page 33 of 37
Figure 10:RX-Control Signal
Call breaks / No service
G701 13MHz Oscillator out of range or high spurious emission
•
Set the handset to call mode, check if some phase and frequency errors appear special in GSM 1800 band
The deviations will be higher the higher the traffic channel is!
•
Change the G701 13MHz Oscillator
COBBA N200 broken solder balls
•
Check VBB 2,8V DC on C117 near to CCONT
•
Check VCOBBA 2,8V DC C148 near to COBBA
•
Check COBBACKL 13MHz 3,2Vpp on J 201 (see the diagram in chapter "COBBA contact service" )
•
Check the module in call modus with a simulator.
•
Knock very careful with something no metalled around the COBBA
•
Check if some errors appear on the tester (phase /frequency / RX-Quality/TX-Power level)
•
Check the COBBA IC with a microscope, the first broken balls are normal on the corners from circuit.
•
Change the circuit with a μBGA solder machine
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