Test 39 Tn Vctcxo Frequency Limits [-150, 150] - Nokia RH-17 Series Troubleshooting - Rf

RH-17
Troubleshooting — RF
as listed in Table 1 for AMPS Power Level 5. Read the phone's current on the power sup-
ply and check to see that it is within the limits. If the power supply does not display cur-
rent draw, use a current meter in series with the phone. If the phone powers down when
the mode is set, it may be that the phone is drawing more current than the current limit
setting on the power supply.
Troubleshooting:
If current is very high, there may be a short circuit on the phone caused by a solder
bridge, a failed component that is internally shorted, a component placed with the
wrong rotation which shorts two nodes that shouldn't be, or some other reason. A visual
inspection can find solder bridges or wrong component rotations. A failed component
can be found by functional tests of the phone's sub-blocks.

Test 39 TN VCTCXO Frequency Limits [-150, 150]

Description:
The purpose of this tuning is to determine what the AFC DAC value needs to be in order
to center the VCTCXO frequency. The CDMA transmitter is turned on and no TX baseband
modulation is provided. The carrier is then centered in frequency. This is done to the car-
rier after it has been mixed up to 836.52 MHz, since it's easier to measure the tolerance
of 1 ppm at 836.52 MHz than it is at 19.2 MHz. Additionally the tone at 836.52 MHz can
be measured without taking the phone apart.
Explanation of Result:
The result is a frequency offset in Hz of the 836.52 MHz carrier which must be within +/
- 150 Hz.
Manual Verification:
Using the RF Main Mode window in Phoenix, turn on the CDMA transmitter, and set it to
channel 384. Do not add any modulation(Rho).
Using the RF Batch Tuning window, you can check the VCTCXO tuning value. Look for a
transmitted tone on the spectrum analyzer at 836.52 MHz. If no tone is present, proceed
to troubleshooting section.
Go to Phoenix PDM Control and follow instructions that follow. Center the carrier to
within +/- 150 Hz of 836.52 MHz. (If sidetones are present, be careful to center the car-
rier and not one of the sidetones, which will probably have a higher amplitude than the
carrier.) The values you enter in the "values" edit box are the AFC values which control
the VCTCXO frequency. Start with a value of 0, then adjust until it is centered, staying
within the limits.
Troubleshooting:
If there is no tone, probe pin 3 of G501 for a tone at 19.2 MHz. If this is not present
check power supplies, particularly ensure 2.7v on VCTCXO Vcc pin, pin 4 of G501. Also
check the control pin, pin 1 of G501, for a voltage between 0.4 and 2.7 v. If the voltages
are correct, and soldering of all G501 terminals is correct, replace G501. If 19.2 MHz tone
Page 28
Nokia Corporation
CCS Technical Documentation
Confidential Issue 1 04/2003