Nokia NHL-4 7210 Service Manual page 162

NHL-4/4U
Troubleshooting Instructions
6\QWKHVL]HU WURXEOHVKRRWLQJ GLDJUDP
Synthesizer
troubleshooting
Yes
Set with RF controls:
Active Unti = Rx
Operation mode = Continuous
Check with RF probe:
-4G VCO out signal
- 3589.6 MHz (GSM900)
-3495.6 MHz (GSM1800)
- 3760 MHz (GSM1900)
Level >-10dBm (*
No
VCO out signal level<-10dBm
No
Check output signal on
1 GHz span
Signal found on
incorrect frequency ?
Yes
Check with oscilloscope:
VCO control voltage
from VCO pin
0V ?
No
Check with oscilloscope:
VCO control voltage
from VCO pin
>4.0 V ?
3DJH 
Company confidential
)LJXUH 
*(When 2.5kOhm passive probe is used,
correct the measurement by +34 dB
Yes
Yes
OK ?
Check with oscilloscope:
-4G VCO Vcc = 2.7V
No
Yes
Check balun
output levels and
solder joints
OK ?
Check VCO control
loop components
1RNLD &RUSRUDWLRQ
CCS Technical Documentation
Synthesizer
OK
Check balun
output levels and
solder joints
OK ?
No
Replace
faulty
component(s)
Yes
OK ?
No
No
Yes
OK ? No
Yes
Replace
VCO
Yes
Replace
VCO
Baseband
troubleshooting
Replace
faulty
component(s)
,VVXH