XIEGU
Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver
XIEGU All Rights Reserved Version No.: 1.0 2022-07 Page
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Fault phenomenon: no ATT function (after turning on ATT, the amplitude-frequency curve of
network analysis does not lower)
Maintenance methods:
Mainboard of the old version:
For the mainboard of the old version G90-SSIGBD-V2.0.7-GAI03, the
fault is mainly caused by false welding and bumping.
Fault
Phenomenon
Maintenance Method
Small signal board
Checkpoint
ATT function
failure
Check whether the components
are damaged or broken
A14
Check the ATT unit for false
welding during other periods
ATT unit
Mainboard of the new version:
For the mainboard of the new version G90-SSIGBD-V2.1.1, the fault is
mainly caused by the damage of radio frequency switch AS179 or the
abnormal control level of AS179. Check whether the control level can
normally turn between high and low when it is in on/ off state of ATT.
In the left figure, the circuit composition of the three AS179 in the ATT
unit is shown in the SCH document. The signals are measured in
sequence, and the signal strength measured at A15 shall be as follows:
Checkpoint
Frequency
MHz
Amplitude
mVpp
State
A15
14.271
380
Close ATT.
Open PRE
14.271
45
Open ATT
Note: AS179 component is vulnerable to the electrostatic
damage and in a state of incomplete damage, showing the
phenomenon of increase of interstage insertion loss. Carefully
measure the input and output signal amplitude of each AS179 and
pay attention to the abnormal changes.
ATT unit
ATT unit
