XIEGU
Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver
XIEGU All Rights Reserved Version No.: 1.0 2022-07 Page
17
of
48
Checkpoint
Frequency
Amplitude
mVpp
Name
A5
1kHz
350
Baseband
signal
The frequency measured at the two test points at checkpoint A5 shall be 1kHz, and amplitude is
basically the same (the allowable difference is within 10mV).
5. After measuring according to the sequence of each checkpoint in the above steps, if the value
measured at a checkpoint is not consistent with the standard value, it indicates that there may be a
fault.
6. If no signal is measured when measuring checkpoint A3, directly measure whether there is an input
signal on the terminal of the antenna pedestal:
If signals can be measured at the antenna pedestal, while cannot be measured at the checkpoint
A3, it indicates that there may be an open circuit fault in the IPX signal line for receiving, or there
may be a short circuit in the outlet socket for received signal of the base board.
If signals cannot be measured at the antenna pedestal and the checkpoint A3, it indicates that
there may be a short circuit fault in the IPX signal line for receiving, or there may be a short
circuit in the outlet socket for received signal of the base board.
Treatment: Check whether the socket for receiving signal is short-circuited, replace with a new IPX
signal line, and test again.
If signals can be measured at the antenna pedestal while cannot be measured at the lower end of
the antenna-coupling capacitor, it is likely that the antenna pedestal lead is poorly welded to the
base board, or the pad of the base board falls off, or the antenna-coupling capacitor is faultily
welded
7. If there is a signal at the checkpoint A3 while no signal at the checkpoint A4, it is related to the
failure of the BPF unit. The troubleshooting of such faults is explained in the following chapter of BPF
fault.
8. When setting the volume at about 80%, a sine wave signal shall be measured at the checkpoint A6 at
the output terminal (PIN-5) of LM386:
Checkpoint
Receiving Frequency
MHz
Amplitude
Vpp
Frequency
Signal
A6
14.270
1.95
1kHz
Relatively standard sine
wave
Special reasons for some "Receive Failures":
The IPX line for receiving is damaged.
The RX signal base next to checkpoint A3 is welded reversely in direction.
The gas discharge tube on the left side of checkpoint A3 is broken down.
Antenna
Coupling
capacitor
Outlet socket
for received
signal