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NHM-2/5nx,ny/6/9
Troubleshooting
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Fault finding chart for GSM1800 transmitter
Measure TX
Measure TX power
power on "ANT"
No
on DCS_Tx. Power
Power > 27.5
~7 dBm in 500 ohm
dBm in 50 ohm
Yes
Yes
With Osc on
Check POGO
RXTX switch
pins, C593, L510
check: Vc1 =
2.7V, Vc2 = 0V
Yes
Check RXTX
switch
TXIQ signals look the same in EGSM and GSM1800.
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There is only one PLL synthesizer generating frequencies for both Rx and Tx in both bands (EGSM
and GSM1800). VCO frequency is divided by 2 or by 4 in HAGAR depending on which band is active.
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Measure TX
Measure TX
power on "Pout".
power on "Pin".
No
No
Power ~7 dBm in
Power ~-17 dBm
500 ohm
in 500 ohm
Yes
Yes
With Osc on PA
Check L515
check:
(Coupler)
Vpctrl GSM1800.
Vpctrl ~ 1.5Vpp
Yes
Check PA N502
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PAMS Technical Documentation
No
T503. Power ~18
With Osc check
No
TXC (see figure
?)
Yes
With Osc check
"Vpctrl" = "TXC"?
No
Check V503 +
discretes around
No
No
Measure TX
With Osc check:
power unbal
VTX = 2.7V +
No
discretes around
dBm in 500 ohm
T503
Yes
Check R542,
R539, R543,
C566/Z504
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No
Check Hagar +
Serial bus
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