Nokia RH-10 Series Troubleshooting Manual page 9

CCS Technical Documentation
1 ppm at 1880 MHz than it is at 19.2 MHz. Additionally, the tone at 1880 MHz can be
measured without taking the phone apart.
The result of this test is a PDM value for the AFC DAC, which must be within +/- 150,
corresponding to 2.2v on the VCTCXO control pin (pin 1) and the carrier centerd within
+/- 100Hz. The VCTCXO must be able to be centered within a certain voltage range in
order to allow for aging of the crystal (the centering voltage slowly drifts over time and
the phone will eventually run out of voltage range if it begins too close to the edge of
the range).
Manual Verification: Using the "RF Main Mode" dialog box in Phoenix, turn on the PCS
transmitter and set it to channel 600. Do not add any modulation. Using the RF Tuning
window, set Mode=RF Tuning, and choose this tuning. Look for a transmitted tone on the
spectrum analyzer at 1880 MHz. If no tone is present, proceed to Troubleshooting below.
Center the carrier to within +/- 100 Hz of 1880 MHz. (If sidetones are present, be careful
to center the carrier and not one of the sidetones.) The values you enter into the Values
edit box are the AFC values that control the VCTCXO frequency. Start with a value of "0",
adjusting until it is centered, staying within the set limits.
Troubleshooting:
1 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 ensuring 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 2.7v. If the voltages are correct, and soldering of all G501 terminals is
correct, replace G501. If 19.2 MHz tone is present but tone at 836.52 MHz is not,
troubleshoot Cell TX Chain section.
2 If the carrier is present but the PDM needed to center it is outside of the +/- 150
range, or if it cannot be centered, there is a hardware problem.
3 In the following procedure, performing frequency centering on the RF carrier at
1880 MHz will detect frequency errors due to the VCTCXO and supporting hard-
ware, which will be the majority of the problems, but will not detect frequency
errors due to the hardware that mixes the VCTCXO tone at 19.2 MHz up to
1880 MHz. In order to also troubleshoot this hardware, frequency centering
should be performed on the 19.2 MHz tone to +/- 19.2 Hz on pin 3 of G501,
using a frequency counter. Then the VHF and UHF LOs should be checked. (Since
this will be time-consuming and will probably only account for a small percentage
of the failures, it is not recommended unless the situation justifies the time spent.)
The VHF LO is inside the Robin IC (N601) and troubleshooting of the Cell UHF LO
is according to Table 2.
4 If the carrier can be centered, but the PDM is out-of-range, check the control
voltage on pin 1 of G501. If it is 2.2v (and pin 4 is at 2.7v and pin2 at 0v), then
the VCTCXO (G501) is working correctly but the circuit that delivers the control
voltage is not. Check soldering of all G501 terminals; also check R510, R511,
Issue 1 09/2002
Nokia Corporation
Confidential
RH-10
Troubleshooting
Page 9