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PAMS Technical Documentation
First precondition for Hagar to be in active (ON) mode is that HAGAR_RESET_X should be high (2.8V)
and VREF, which is Hagar reference voltage, at 1.35V.
Easiest way to check these two voltages is by using oscilloscope with an standard passive probe
(10kΩ/8pF). HAGAR_RESET_X is measured on C540 and VREF on C536.
Another " good spot" to check if Hagar's internal supplies are active, is to measure either on capacitor
C538 or resistor R511. R511 is Hagar connection for a external resistor in order to create inernal bias
currents. This volage should be excactly the same value as VREF on C536.
Next step towards examination of the the Hagar functionality can be based on verification of some
important bias voltages and bias controls. Those signal coming from Hagar and they are used for con-
troling the LNA's biasing(both 900/1800MHz), LNA power supply and TX power detector .
As a reference, here is a list of some typical test points for both Rx and Tx mode:
Frequency Band
EGSM
GSM1800
,VVXH $SULO
RX
² 900 LNA bias control - L506 (pulses
with ≈2.34V )
² 900 LNA power supply control –
R514( pulses with ≈2.75V)
² 1800 LNA bias control – R502
(pulses with ≈2.34V)
² 1800 LNA power supply control –
R513( pulses with ≈2.75V)
1RNLD &RUSRUDWLRQ
NHM-2/5nx,ny/6/9
Troubleshooting
TX
² supply for the 900 PA buffer – R606
(pulses with ≈2.34V)
² bias voltage for power detector –
C573 ( "high" 2.8V)
² bias voltage for power detector –
C573 ( "high" 2.8V)
3DJH
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