Vctcxo Troubleshooting - Nokia RM-11 Series Troubleshooting Manual

RM-11
Troubleshooting - RF

VCTCXO Troubleshooting

The VCTCXO frequency is 19.2MHz. This is the reference signal. Without 19.2MHz, the
mobile terminal does not power up. This signal goes to N701, N601, UHF PLL, and also to
the UPP via a buffer amplifier (D572). Check for the presence of the signal at the
following points (use a high-impedance RF probe):
• CLK19M2_B, clock reference to N701, should be +4.5dBm
• CLK19M2_R, clock reference to N601, should be +4.5dBm
• CLK19M2_UPP, clock reference to UPP, should be +7.5dBm
If you do not see the VCTCXO signal at any of these points, check the voltages at the
following supply lines:
• VR3, main supply line for VCTCXO circuitry, should be 2.78VDC
• VIO, supply line for buffer amplifier, should be 1.8VDC
VCTCXO
To N701 PLL
19.2MHz @ +4.5 dBm
(CLK19M2_B)
To N601 PLL
19.2 MHz @ +4.5dBm
(CLK19M2_R)
To BB UPP
19.2MHz @ +7.5dBm
(CLK19M2_UPP)
© 2005 Nokia Corporation
Page 32
VR3 = 2.78VDC
Confidential
CC Technical Documentation
VIO = 1.8VDC
Issue 2 09/2005