St Tx Detector Cell - Nokia NPD-1 Series Troubleshooting - Rf

CCS Technical Documentation

ST TX Detector Cell

This is one of the phone's self tests which gives either a "pass" or "fail" result only. The
phone transmits at several power levels and checks the ADC value of the power detector.
The ADC value is measured first for a set of AGC values, then each AGC value is changed
one at a time to make sure that the ADC changes as each AGC is changed individually.
Manual Verification:
Using Main Mode: Turn on the Cell CDMA TX with channel set to 384, and turn on IS95
modulation using CDMA control.
Using the PDM window, set:
TX_IF_AGC to – 100
TX_RF_AGC to –512
PA_AGC to +511.
Record the TX signal power from the antenna connector using a spectrum analyzer cen-
tered at 836.52 MHz. (The selftest measures the power detector reading instead, but at
the present time this cannot be done with Phoenix; therefore, an easy way to check
functionality without removing the covers is to check transmitted power. If the covers
are removed, the voltage on PWR_OUT, at probing point 48 in Figure 1, can be mea-
sured). Transmitted power should be greater than 24 dBm. (PWR_OUT greater than 1.91v,
which corresponds to the power detector ADC=700).
For each of the next three cases, TX power should be less than 24 dBm (less than 1.91v
on PWR_OUT).
(1) TX_IF_AGC to – 80
TX_RF_AGC to -512,
PA_AGC to -512.
(2) TX_IF_AGC to +511,
TX_RF_AGC to -512,
PA_AGC to +511.
(3) TX_IF_AGC to -80
TX_RF_AGC to +511
PA_AGC to +511.
Troubleshooting: If there is a failure associated with only some of the cases above, check
the AGC voltages and components of the associated PDMs as described in Tables 1 and 3.
For problems with the IF or RF AGC, also check Robin and supporting components. For PA
AGC problems, also check the PA and supporting components. If all of the above cases
fail, troubleshoot the TX chain as described in the Probing Diagrams section. If all the
output powers are passing, then perhaps the test is failing because the ADC voltage is
wrong (which at this point we cannot read, so we are measuring the actual output
power). This can be verified by measuring the voltage on the PWROUT probing point 48
Issue 1 11/2002
Nokia Corporation
Troubleshooting — RF
Confidential
NPD-1
Page 9