Nokia 3155i Troubleshooting Manual page 9

Nokia Customer Care
• When flashing or erasing the mobile terminal, monitor the MBUSRX and FBUSRX
signals from the UEMEK to the D2800 processor for a signal at these points. If
either signal does not appear, check the signal at the production test points. If
the signal is ok, check the UEMEK. Re-flow or replace the UEMEK.
• Next make sure that the D2800 processor sends information back to the FPS-8
through the FBUSTX signal. If there is no activity at this point re-flow or replace
the processor.
• If all points are ok, make sure the FBUSTX signal goes through the UEMEK by
measuring the signal at the FBUSTXO at production test points. If there is no
signal present, reflow or replace the UEMEK.
• If all signals form the production test points to the UEMEK to the D2800
processor are functioning, it is safe to assume that the UEMEK and D2800
processor are ok.
Continue troubleshooting the D2800 processor as it interfaces with the flash. Verify the
available signal interface between the processor and flash as follows:
• Erase or program the mobile terminal to monitor the D2800 processor and flash
interface as verified earlier using Phoenix External.
• When programming or erasing the mobile terminal, monitor the FLSCSX, FLSCLK,
EXTRDX, and EXTWRX flash signals. If any of these signals has no activity, re-flow
or replace the D2800 processor.
• If all signals are ok, re-flow or replace the flash.
If additional troubleshooting is still required to determine why the mobile terminal
cannot be flashed, verify all the baseband voltages. In particular, check the VIO since it is
one of the regulators that powers the flash chip.
ISSUE 1 07/2005
©2005 Nokia Corporation
3155/3155i (RM-41), 3152 (RM-61)
Baseband Description and Troubleshooting
Company Confidential Page 9