Vhf Vco Troubleshooting - Nokia NSW-5 Series Service Manual

NSW-5
Disassembly and Troubleshooting Instructions

VHF VCO Troubleshooting

Is oscillator
locked ?
Check oscillator
output level and
frequency at
C744
Check N770
Check PD1 at
C790
V=1–2 (LB)
=2.8–3.8 V (HB)
Check
EROTUS
supply voltages
Check
Check
EROTUS
Change
EROTUS
supply voltages
EROTUS
supply voltages
Page 48
N
Check EROTUS (N750)
Y
(SCLK):2.8V
(SDATA):2.8V
(SENA1):2.8V
SENA is 0 during SCLK
and SDATA
N
N
Change N770
Y
Y
Change V723
N
Start BB trouble
N
shooting
Y
E Nokia Mobile Phones Ltd.
PAMS Technical Documentation
Note!
The Oscillator is locked, when
the frequency and Vcnt are
stable.
Frequency=322.38/392.46MHz
Vcnt=1 .3.8V,C790
N
Start BB
troubleshooting
Note!
SENA1 = EROTUS PLL
Note!
Check all solderings,missing
components and supply voltage
VR3.
Note!
Check all solderings and
missing components
Note!
Check all components and soldering
Issue 1 10/00