Philips CT6558 Tuning Up Procedure & Operational Manual page 17

PHILIPS
Tuning Up procedure & Operational Manual
TX circuit troubleshooting:
Key parameter of Tx circuit is "Freq. error", "MAX POWER", "TX-CURRENT", "PA table", etc.
Following is normal analysis of the circuit, according to failed item to do more analysis.
Confirm the instrument for analysis is good:
a. Power on radio, press 'Tx command' button, setting up the channel and power level.
b.
Set the right frequency and sweeping time on spectrum analyzer.
c.
Set up the voltmeter and oscilloscope.
Step1: Measure the I/Q signal from CPU (7300) to modulation and demodulation IC (7130). If the I/Q signal is not good,
check CPU.
Step2:
if I/Q signal is good, Measure the output signal of 7130, If the signal is not good, check 7130, and parts
around 7130.
Step3:
If the signal output from 7130 is right, continue to measure the TX signal at Balun circuit, and check balun
Circuit parts around.
Step4:If the output signal from Balun circuit is good , continue to check output signal of PA. Measure the EGSM
signal at pin12 of PA; Measure DCS signal at pin17 of PA. If the output signal is not good check PA or parts around PA.
Check the operating voltage "VBAT" and control signal.
Revision :
Date :2004-9-7
Page No. : Page 17 of 17
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