Phone Fails After Power On; Measurement Points At The Vcxo - Nokia RM-4 Troubleshooting Instructions

RM-4/RM-5
Troubleshooting Instructions

Phone fails after power on

If the phone stops working a short time after the power is turned ON, a possible reason for this
could be that the 26MHz system clock signal is not getting to the UPP clock-input in BaseBand.
In this case check the following:
1 Turn on the phone and check
2 VCXO Power supply (C620) = 2.7V
3 VCXO output (R420 – end not
If this is not the case check the reference crystal (B600) and Mjolner (N600) as well as R420,
R426, C420, C426.

Measurement points at the VCXO

ISSUE 1 02/2004
connected to C425) is 26MHz and approx. 700mVpp
Figure 22: Measurement point for VCXO supply
Figure 23: Measurement point for VCXO output
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