Frequency Synthesizer - Nokia NHL-2NA Series Troubleshooting Instructions

NHL-2NA

Frequency synthesizer

Synthesizer
troubleshooting
Set with Rf controls:
Active unit = RX
Operation mode = continuous
Check with Rf probe 4G VCO o/p
signal
3769.6MHz (GSM900)
3685.6MHz (PCN1800)
Level > -37dBm
OK?
NO
4G VCO o/p
signal level
< -37dBm ?
NO
Check output signal on
1GHz span
Signal found on
incorrect frequency?
YES
Check with
oscilloscope VCO
CONTROL
OV ?
NO
Check with
oscilloscope VCO
CONTROL
> 4V ?
Page 18
synthesizer
YES
Check balun
T580 output levels
and solder joints.
YES
OK?
Check with
oscilloscope VCO
Vcc=2.7V
NO
OK?
NO
Baseband
troupleshooting
Check balun
T580 output levels
YES
and solder joints.
OK?
YES
Check VCO control loop
components
C581,C582,C583,R580
and R581
OK?
YES
Replace VCO
¤Nokia Corporation
CCS Technical Documentation
OK
Replace faulty
NO
components
YES
Replace VCO
YES
NO
Replace faulty
NO
components
Issue 1 07/02