NHM-2/5nx,ny/6/9
Troubleshooting
PAMS Technical Documentation
3DJH
1RNLD&RUSRUDWLRQ
,VVXH$SULO
9&2
The VCO is generating frequencies in the range of 3420 – 3840 MHz when PLL is in function. These
are divided by 2 or by 4 in HAGAR so that they can generate all channels in EGSM and GSM1800.
Frequency of the VCO is controlled by dc voltage ( Vc ) coming from the loop filter. Range of the Vc
when PLL is in function is 0.7 – 3.8 V. Even if PLL is not in lock state (Vc out of range) there is some
frequency at the output of the VCO ( G500) which is between 3 and 4 GHz. This is of course true only
if VCO is working and if VCO power supply is present (2.7V).
)DXOWILQGLQJFKDUWIRU3//6\QWKHVL]HU
It is important to say that power supply for VCTCXO ( VXO) is OFF only in ‘Deep Sleep Mode’ and
power supply for VCO ( G500 Vcc) is OFF in ‘Sleep Mode’.
From WinTesla chose:
Product > Band > EGSM
Testing > RF Controls >
Rx continuous > Ch 60
Spectrum Analyzer
VCO (G500) output at
T502, 3788 MHz
No
Yes
PLL block functional
Oscilloscope
VCTCXO (G502) Power
Supply Vtcxo at C543 -
2,7 V
Oscilloscope
VCTCXO output,
26 MHz at C546 -
approx. 1.2 Vpp
VCTCXO is dead
Oscilloscope
VCO Power Supply
VCOS at R202 - 2,7 V
Yes
No
Check CCONT,
Software?? Phone not in
function
Check CCONT,
Software?? Phone not
in function
Spectrum Analyzer
VCO output at T502
Some signal between 3
and 4 GHz
VCO is dead
Check HAGAR,
wrong writting to HAGAR
(SCLK,SDATA,SLE,
HAGARRESET)
Yes
No
No
Yes
Yes
No