XieGu G90 Maintenance User Manual

Document No.:

Short-Wave Transceiver Series

Maintenance Manual

XIEGU

Classification Level:

Version: First Edition

Private and Confidential!

Revision: 0

Revision Date: July 27, 2022

G90/G90S

Confidential

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Contents

I. Overview of the Whole Device G90/G90S is a short-wave transce iver with ZIF zero-IF structure, built-in automatic antenna tuner , and a transmitting power of 20W. The block diagram of each part of the whole device is as follows: Small signal board unit:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Display unit:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Base board unit:

Basic skills of board-level maintenance:

1. Be familiar with the circuit structure of the whole device and accurately grasp its signal flow.

2. Be familiar with the status of each working voltage and be able to measure it accurately.

3. Be able to operate the radio proficie ntly and combine var ious operations to su pport the maintenan ce process.

4. Be familiar with the meaning of each physical quantity and use it in combination with the actual situation of the overhauled product.

5. Be able to skillfully use and set commonly used measuring instruments and meters.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

 The head of G90 can be separated from its body, with hot swap supported. Therefore, in the

maintenance process, this feature can be u tilized to quickly l ocate whether the f ault point is in the main unit or the head unit.

 The heads of different versions c an be interchange d, and the replace ment method can be ta ken to

quickly locate whether it is the fault of the head.

Main troubleshooting methods:

 Check according to the signal flow direction: Check step by step along the signal flow to find

abnormalities.

 Judge based on voltage/ current: According to the measured voltage or current, quickly and

roughly judge whether t he product has a short circu it/ open circuit. Take full advantage of therm al imager to troubleshoot short-circui t poi nts.

 Component-level inspection: Perform fault inspection according to the inherent characteristics

of components. To sum up, the maintenance personnel need to have a comprehensive understanding of the overall structure, signal flow, unit function, and operation method of the product, and at the same time arm themselves with certain basic knowledge of module and cir cu it.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Display

Whole device

The LED light

does not light up

Check its welding

direction

Maintenance Method

Display

Location

not light up

are faultily welded

Checkpoint 1

Next, each circuit board will b e regard ed as a unit to e xplain the j udgment, detect ion and main tenance of faults by categories in combination with common fault phenomena. Some fault phenomena have appeared to be the same on the single board and the whole device. Therefore, the maintenance method of the same faul t on the si ngle boa rd and the w hole de vice will be explained at the same time.

II. Board-Level Maintenance

2.1 Display  Fault phenomenon: The indicator light does not light up

Fault

Phenomenon

The bicolor

LED light does

Check whether the two

resistors on the back

/

Checkpoint 1

 Fault phenomenon: The display is blank

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Display

Checkpoint

Check whether the FPC pedestal is faultily welded

Check whether there is any false

A

Blank display

welding at the MCU pins

 This fault is mostly caused by the false welding of components.  During repair welding of the FPC pedestal, it is necessary to

shorten the welding time as much as possible to avoid thermal deformation of the pedestal.



B

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Display

Checkpoint

Check whether the voltage

is 3.3V

is faultily welded

Maintenance Method

Display

Checkpoint

High current and

Check whether the voltage

Fault phenomenon: It cannot be written into Bootloader or the application

 Fault phenomenon: high current

Failure to burn

program

Check whether the MCU is

faultily welded

Check whether the pedestal

Fault

Phenomenon

hot MCU

 If the voltage at point C > 3.3V, the LDO regulator has already

been damaged. It is necessary to replace the LM1117-3.3 regulator first, confirm that the output voltage is 3.3V, and then replace the damaged MCU. Otherwise, it will cause a secondary fault to burn the MCU.

 During the maintenance, it has ever been found that the short

circuit of the display FPC pedestal welding lead to the 3.3V grounding short circuit, where attention to check is thus required.

is 3.3V

C

B

D

C

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Maintenance Method

Checking

Fault

Maintenance Method

Display

Checkpoint

The top button

 Fault phenomenon: no power for the hand microphone input, no action after hand microphone

buttons are pressed, and no backlight at the hand microphone

 Fault phenomenon: The top button does not respond when it is pressed

Fault

Phenomenon

The hand

microphone

does not

components in this area are

respond

 Check whether the elastic contacts in the RJ45 pedestal are in

good condition, and whether there is def ormation or dislocation.

Display

Check whether the

faultily welded

Area

E

Phenomenon

does not respond

when it is pressed

 Check whether the components on the top button board are

faultily welded.

 Check whether the connecting lines are in good contact and the

line sequence correct.

Check whether the socket

pins are faultily welded

F

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Display

Checkpoint

No

and the host

Check whether the MCU pins Check whether the ESD diode is broken down

Display

Checkpoint

Check whether the two pins of

themselves

Check whether there is

Encoder

Button

Encoder

Button

 Fault phenomenon: The device head cannot comm unicate wit h the host, an d the s cr een dis plays

COMM LOST

 Fault phenomenon: The starting-up speed is too fast, and it enters the main interface as soon as it

flashes/ cannot enter the flashing state

communication

between the

are faultily welded and whether the chip is damaged

B

device head

 In addition, note to check whether the DB9 connection board is

faultily welded.

Fault

Phenomenon

Maintenance Method

G

Fast starting-up speed/ failure

all buttons are short-circuited by

to enter the flashing state

grounding short circuit of all encoder pins

Button

Encoder

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Maintenance Method

Display

Checkpoint

Check whether the encoder

grounding short circuit

when it is pressed

is pressed

Button

 Fault phenomenon: The encoder does not respond when it is pressed

 Fault phenomenon: A certain button does not respond when it is pressed

Fault Phenomenon

The encoder does not respond when it is pressed

 Also pay attention to whether the other three pins of the encoder

are short-circuited by lap welding of adjacent pins.

 Some of these fault points are very subtle, such as PCB

disconnection, or rubbing of the solder mask on the PCB by the metal fixing pins of the encoder, resulting in a grounding short circuit of the pin wiring.

Fault

Phenomenon

A certain button

does not respond

switch pins are faultily

welded or there is any

Maintenance Method

Display Checkpoint Check whether the two pins are connected after the button

H.J.K

Fault button

 Check with power off.  Some of these fault points are very subtle, such as PCB

disconnection, or rubbing of the solder mask on the PCB by the metal of the button casing, resulting in a grounding short circuit.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Receiving mixing

Transmitting mixing

Audio amplifier unit

Earphone/ horn switch

Baseband unit

Local oscillator unit

Main MCU

BPF unit

External

2.2 Small Signal Board At present, there are mainly two versions of small signal board s with large production volume, i.e. G90-SSIGBD-V2.0.7-GAI03 and the current version G90-SSIGBD-V2.1.1. The old version is the same as the current version in terms of principle, with only part of circuit units having been changed. This manual is to explain in accordance with version V2.1.1. The distribution of each unit of the small signal board is shown in the following diagram:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Measurement

Point

Audio unit reference voltage

Vref

Local oscillator unit power

supply

Q

3.3

Baseband unit power supply

S

3.3

MCU power supply

T

+9

Public 9V power supply

U

+9T

Transmitting 9V power supply

V

+9R

Receiving 9V power supply

W

+5

Public 9V power supply

Measurement

Point

Frequency

MHz

Amplitude

Vpp

X

12.288

3.9

CODEC clock

TXCO

reference clock

Local oscillator

output

MCU clock

frequency

The general parameters of each basic measurement point on the small signal board are as follows:

 We are to explain with the default test frequency point of

14.270MHz as an example. The maintenance test frequency p oint of each subsequent step is considered to be 14.270MHz by default.

Voltage V Name

Maintenance methods:

N 0.94～0.98

M 3.3

 +9T is only available in the transmitting state, and it is

theoretically 0V when receiving.

 +9R is 0V in the transmitting state.  +9, +5, and each 3.3V voltage are a vailable in both the receiving

state and the transmitting state.

Name

P 26.000 3.6

L 14.270 5.9

R 8.000 1.94

 The local oscillator outputs two signals respectively, and their

frequencies are the same, both of which are the currently set receiving and transmitting frequencies.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave T ransceiver

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

1. Check whether the 3.3V power supply is normal

main MCU pin

 Fault phenomenon: It cannot be written into Bootloader or the application

A1

Inability to

burn or start up

the application

 Pay attention to the damage of COMM socket, such as short

circuit, open circuit, etc. Me asure w het her the r eleva nt le ads fr om A3 to A2 are connected through the on-off position of the multimeter.

2. Check whether the main MCU pins are faulty welded

3. Check whether the COMM socket is connected with th

e

A2

A3

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

3

14.271MHz

-20dBm

Y-axis: 100mV

Frequency

MHz

Amplitude

Vpp

TXCO reference

clock

Local oscillator

output

Checkpoint

Frequency MHz

Amplitude mVpp

A3

14.271

80

A4

14.271

380

Setting Parameters

Parameter 1

Parameter 2

Parameter 3

Time base:

1ms

Y-axis: 100mV

 Fault phenomenon: receive failure (or no signal tone)

1. First, check whether the local oscillator on the small signal board works normally. Instrument settings:

Name

Signal Source

Oscilloscope

 Note: The oscilloscope shall be set at X1 0 gear , and the test pr obe

shall also be set at X10 gear. Coupling mode: AC coupling.

2. First measure the working condition of local oscillator, and the test data shall be roughly as follows:

Checkpoint

A1 26.000 3.6

A2 14.27 5.9

 The upper end of the two resistors at A2 checkpoint is for the

quadrature output of the local oscillator signal, with the same frequency and amplitude.

3. Connect the output signal of the s ignal source to the small signal board, and measure the signal strength of checkpoints A3 and A4 respectively in turn. Normally, it shall be as follows:

Parameter 1 Parameter 2

Frequency:

Time base: 50ns

Amplitude:

/

X10 gear

Name

Maintenance methods:

 During the above test, PRE shall be turned on.

4. Measure the signal strength of checkpoint A5 as follows: (signal source output: -40dBm)

Name

Oscilloscope

X10 gear

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Amplitude

mVpp

Baseband

signal

Receiving Frequency

MHz

Amplitude

Vpp

Frequency

Signal

1kHz

Relatively standard sine

wave

Antenna Coupling capacitor

Outlet socket for received signal

Checkpoint Frequency

A5 1kHz 350

Name

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 me asur ed w hen m ea suri ng chec kp oint A3, directly measure whether there is a n 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 c ircuit fault in the IPX signal line for receiv ing, 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 meas ured at the l ower 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 s uch faults is ex plained in the fo llowing chapter of BPF fault.

8. When setting the volume at a bout 80%, a sine wav e signal shall be measured at the chec kpoint A6 at the output terminal (PIN-5) of LM386:

Checkpoint

A6 14.270 1.95

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.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Maintenance Method

Checking

Area

Whether there is false welding in the

switching control area

Setting Parameters

Parameter 1

Parameter 2

Parameter 3

14.271MHz

-20dBm

Y-axis:

100mV

Frequency

MHz

Amplitude

mVpp

A3 14.271 80

Input of each segment

of BPF

Output of each segment

of BPF

A4 14.271

380

Receive mixer input

 Fault phenomenon: BPF unit test fault (there is no amplitude-frequency curve in network

analysis test)

Maintenance methods:

1. First check the band switching control area on the back of the small signal board:

Fault

Phenomenon

Small signal board

No BPF

A8

2. Set the instrument:

Name

Signal Source

Oscilloscope

Frequency:

Time base: 50ns

Amplitude:

/

X10 gear

Then check whether the signal amplitude of checkpoints A3, A6, A7, A4 is normal in turn.

 Area A6 collects the input of each segment of BPF;  Area A7 collects the output of each segment of BPF;

When PRE is turned on, the measured data at each checkpoint shall be as follows:

Checkpoint

A6 14.271 80

A7 14.271 50

Name

3. After selecting a certain segment of BPF, the positive pressure differential between the input and output switching diodes of this segment of BPF shall be about 0.7 ~ 0.9V. If the selected BPF switching diode has a reverse pressure differential, it indicates that the gating of this segment is faulty.

4. The fault point of BPF unit can be found out according to the above steps.  The damaged inductance and capacitance in BPF will also cause

faults, so pay attention to that.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

Check whether there is false

welding of components

Check whether there is false

welding of components

Check whether there is false

welding of components

Check whether there is false

welding of components

Check whether there is false

welding of components

Check whether the two diodes

are broken down

 Fault phenomenon: startup failure, unable to connect with the machine head (mainboard MCU

indicator light flashes slowly and is always on)

The main manifestations of such faults are as follows:  After starting up, the blue indicator light beside the main MCU

flashes slowly or is always on.

 After starting up, the level on the machine head display is

-256dBm, and there is no waterfall plot.

Maintenance methods:

IC1

Startup failure

 According to previous maintenance experience, there is a higher

chance of false welding of IC3, which shall be checked

IC2

IC3

IC4

A10

A11

emphatically.

 Principle: IC1, IC2, IC3 and IC4 are for IIC bus comm unicat ion.

When there is a problem in the bus communication of a chip, the communication mechanism will give up the correspondence with

Maintenance methods:

it after a certain time and change to communicate with other remaining chips. The phenomenon when such actions occur:

After starting up, the indicator light is always on, and then starts flashing after about 10 seconds. At the sa me time, the sound of relay operation is heard, and background noise of the horn starts.

Special attention:

 There is a higher defect rate of domestic GD32F450 series chips

(about 4%), causing a lot of failures such as startup failure or connection failure with the machine head.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

3

Frequency:

Amplitude:

Y-axis: 100mV

Frequency

MHz

Amplitude

mVpp

A12

14.271 50

Amplifier input

Amplifier

output

Checkpoint

Voltage

Voltage difference between base (B)

and emitter (E) of amplifier triode

A13

4.5～5V

PRE circuit unit

 Fault phenomenon: no PRE function (after turning on PRE, the amplitude-frequency curve of

network analysis does not rise)

The fault phenomena are as follows: During the network analysis test, turn on/ of f the PRE fun ction, and the amplitude of the amplitude-frequency curve will not change (or become low) Maintenance methods: The instrument settings are as follows:

Name

Signal Source

Oscilloscope

After PRE is turned on, the measured data at each checkpoint shall be as follows:

Checkpoint

A14 14.271 680

If there is a great difference between the measured signal amplitude and the standard data in the table, the following measurements are required:

Parameter 1 Parameter 2

14.271MHz

Time base: 50ns

-20dBm

About 0.55 ~ 0.7V

 At the same time, check whether the PRE control signal

"#PRE_EN" and AS179 controlled voltage turn normally.

/

X10 gear

Name

Maintenance methods:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Maintenance Method

Small signal board

Checkpoint

Check whether the components

are damaged or broken

Check the ATT unit for false

welding during other periods

Frequency

MHz

Amplitude

mVpp

Close A TT.

Open PRE

14.271

45

Open ATT

ATT unit

 Fault phenomenon: no ATT function (after turning on ATT, the amplitude-frequency curve of

network analysis does not lower)

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.

Phenomenon

ATT function

failure

A14

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

Maintenance methods:

sequence, and the signal strength measured at A15 shall be as follows:

Checkpoint

A15

14.271 380

State

 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 out put sig na l am pli tude of e ach AS179 and pay attention to the abnormal changes.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

3

14.271MHz

-40dBm

Y-axis: 100mV

Amplitude

mVpp

Baseband

circuit I

Baseband

circuit Q

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

Baseband amplifier

unit

Whether there is any

false welding

Whether the

welded or defective

Baseband amplifier

Back of baseband amplifier

 Fault phenomenon: The receiving IQ balance cannot be adjusted

Maintenance methods: The instrument settings are as follows:

Name

Signal Source

Oscilloscope

Parameter 1 Parameter 2

Frequency:

Time base: 1ms

Amplitude:

/

X10 gear

After PRE is turned on, the measured data at each checkpoint shall be as follows:

Checkpoint Frequency

Name

A16 1kHz 350

signal of

A17 1kHz 350

If the amplitude differe nce between t he two checkpoi nts exceeds 1 0mV, it means that the baseband signal is unbalanced, and further inspection is required as follows:

signal of

IQ is unbalanced

Back capacitance part

components are fa ul tily

 If the electrolytic capacitor on the back of the baseband amplifier

has individual defects, it will also cause IQ signal imbala nce fault, so it should be checked emphatically.

 100 uF/ 16V chip tantalum capacitor is used for the old version of

the small signal board, which has a high damage rate, so special attention should be paid during maintenance.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

3

14.271MHz

-40dBm

Y-axis: 100mV

Amplitude

mVpp

Baseband

circuit I

Baseband

circuit Q

A18

1kHz

350

Q signal

A19 1kHz 350

I signal

IQ Output amplifier

Output socket

Coupling

 Fault phenomenon: IQ output amplitude is unbalanced (ellipse or a line is displayed)

Maintenance methods: The instrument settings are as follows:

Name

Signal Source

Oscilloscope

Parameter 1 Parameter 2

Frequency:

Time base: 1ms

Amplitude:

/

X10 gear

After PRE is turned on, the measured data at each checkpoint shall be as follows: The working voltage of IQ amplifier should be: 5V

Checkpoint Frequency

Name

PIN1 1kHz 350

signal of

PIN7 1kHz 350

signal of

 If the signal amplitude of a certain circuit is obviously small, it

indicates that there is a fault in the circuit, which should be checked emphatically.

 The coupling capacitor on the back of the small signal board

should also be checked to see whet her the components are faulti ly welded or defective

 The 3.5mm stereo socket of IQ signal output should be checked

to see whether there is a short circuit or open circuit.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

2

Y-axis: 100mV

Frequency

MHz

Amplitude

mVpp

A20

14.27 140 Transmitting +

A21

14.27 140 Transmitting -

A22

14.27 70

Transmitting small signal

Amplified transmitting

small signal

Checkpoint

Voltage V Name

Switching voltage of transmitting

small signal into BRF

Operating voltage of transmitting

small signal amplifier

Transmitting Mixer

TX Baseband Amplifier

TX Small Transformer

 Fault phenomenon: The suppression degree of transmission carrier cannot be adjusted/ no

transmission occurs The two faults have highly coincident inspection parts, so they are explained together.

 Fault cause 1: Carrier suppression caused by transmission

channel fault cannot be adjusted. Check whether the transmitting baseban d am plifier, transmitting mixer and small transmitting transformer have welding problems such as false welding and short circuit.  Fault cause 2: The transmission channel fault causes no

transmitting small signal , and the suppression degree of the

transmission carrier cannot be adjusted. The cause of this fault is the same as the maintenance process without transmitting power, and the maintenance method is as follows: Instrument settings: Switch the test switch to "transmission state", set the radio station to USB mode, set the power to: 20W, and unplug the TX small signal cable.

Name

Parameter 1

Oscilloscope

Press the hand microphone PTT button, and the inspection sequence and operation level of each checkpoint shall be as follows:

Time base: 50ns

Parameter 3

X10 gear

Checkpoint

Name

Maintenance methods:

A25 14.27 500

A23 2.4

A24 5.2

 Before performing the above inspection, it is necessary to

confirm that the local oscil lator u nit sh ould wor k norm ally, or that

the receiving function is norm al and the TX/RX vo ltage switchin g

is normal.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

 Fault phenomenon: There is a bulge in the center of the spectrum display area

 Fault cause 1: IQ signal is unbalanced. The maintenance method

is the same as that of the previous "Receiving IQ balance cannot

be adjusted"

 Fault cause 2: CODEC chip is faultily welded or damaged.

Maintenance methods:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Small signal board

Voltage V

Fault

Maintenance Method

Small signal board

Checkpoint

A30

 Fault phenomenon: Earphones switch silently

1. Press the sound volume button on the machine head and measure

the voltage at the checkpoint:

Earphones switch

silently

2. Check the welding of the followin g points:

Checkpoint A26: horn state 0

Checkpoint A26: earphone state 3.3

Phenomenon

Earphones switch

silently

Check whether there is any false

welding

A27 A28 A29

 Note: when pressing the volume knob to switch the horn/

earphone state, the relay at A28 should have an action sound. In

the previous maintenance process, the relay was found to be

damaged.

Maintenance methods:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

Checkpoint

Voltage V

Name

Checkpoint

Amplitude mVpp

Name

 Fault phenomenon: There is no prompt tone for turning on or off the machine

Maintenance methods:

Name

Parameter 1 Parameter 2

Oscilloscope

Under the receiving stat e, the co ndition of chec kpoint A32 measured is as follows:

A32 0.94

At startup/shutdown, A31 conditions should be measured as follows:

A31 About 100

At the same time, a sine wave sig nal should be se en on the oscill oscope, which is an on/off prompt signal.

Time base: 1ms

turning on or off the mac hi ne

3

Y-axis: 100mV

X10 gear

Operational amplifier

reference voltage

Prompt tone signal for

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

3

14.271MHz

-40dBm

Y-axis: 200mV

Checkpoint

Voltage V

Name

Audio power amplifier

working voltage

Amplitude

mVpp

Audio signal

voltage

Audio signal

voltage

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

Check whether there is any false

welding

Horn socket

 Fault phenomenon: The horn is silent

The instrument settings are as follows:

Name

Signal Source

Parameter 1 Parameter 2

Frequency:

Amplitude:

/

Oscilloscope

Time base: 1ms

X10 gear

After PRE is turned on, the measured data at each checkpoint shall be as follows:

A34 8.9

Maintenance methods:

Checkpoint Frequency

A33 1kHz 50

A35 1kHz 680

Check the welding of the followin g po int s:

The horn is silent

Name

Horn socket

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

3

Function signal

source

kHz

250mVpp

Y-axis: 200mV

Amplitude

mVpp

Audio signal

voltage

Audio signal

voltage

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

No power at the

hand microphone

Check whether all components are faultily welded or damaged

Checkpoint

Voltage V

Name

A39

0.94

Audio reference voltage

Amplitude

mVpp

200

Audio differential

signal amplitude

200

Audio differential

signal amplitude

 Fault phenomenon: The hand microphone has no transmitting pow e r

1. Instrument setting:

Name

Parameter 1 Parameter 2

Frequency: 1

Amplitude:

/

Oscilloscope

Time base: 1ms

X10 gear

2. Connect the test hand microphone to the machine head and measure the status of the following checkpoints:

Checkpoint Frequency

Name

A36-1 1kHz 200

A36-2 1kHz 200

3. Measure whether the two welding po ints of A36 are connected to the lower ends of the two inductors of A37 with the on-off gear of multimeter.

4. Check the welding of the followin g points:

5. The measured data at each checkpoint are as follows:

A37

Maintenance methods:

Checkpoint

A38-1 1kHz

A38-2 1kHz

Frequency

Name

6. Check whether the 16bit-CODEC chip is faultily welded or damaged.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

CW key socket

 Fault phenomenon: Transmit when the machine is turned on (accompanied by a long prompt

tone)

Maintenance methods: Fault cause: CW pedestal is partially short-circuited  Check whether the pins of CW pedestal ar e short-c ircui ted to the

ground and whether the two ESD protection diodes are broken

down.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

 Fault phenomenon: There is no transmission power in the line in pu t

Maintenance methods:

Check the welding of the followin g po int s:

The line input has

no power

 Check whether the Mini-Din8 pedestal is damaged or poorly

contacted.

 Check whether the wire from A41 to A42 is connected.  Check whether the machine head setting is in LINE.

Check whether there is any false

welding

A40 A41 A42

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

 Fault phenomenon: There is no wave band voltage output

Maintenance methods:

Check the welding of the following checkpoints:

There is no wave

band voltage output

 Check whether the Mini-Din8 pedestal is damaged or poorly

contacted.  Check whether the wire from A43 to A44 is connected.

Check whether there is any false

welding

A43 A44

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Power Interface Power Input

Base board G90-BASEBD-V2.0.6

 Fault phenomenon: The plug-in power line is short-circuited to the ground

Transformer

1. Observe whether the pins of the pow er inp ut tra nsfor mer are weld e d reversely. The output of the transformer should be the same winding corresponding to the welding input, and cannot be connected in reverse. After reverse connection, it is shor t-circuit ed directly after pluggi ng in.

2. Observe whether the winding of the transformer is burnt.

3. Measure whether the chip capacitor at the output of the transformer is short-circuited.

Maintenance methods:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Small signal board

Checkpoint

 Fault phenomenon: Short circuit at startup

Maintenance methods:

1. Check whether there is continuous tin electrodeposit caused by the manual welding of components in each point:

There is no wave

band voltage output

2. Check whether components of the 9V and 5V voltage regulators

are installed incorrectly, and check whether the two RD16 are installed incorrectly.

3. Check whether the pins of the output transformer are

short-circuited with the nearby components; or whether there is continuous tin electrodeposit in nearby components.

Check whether there is any false

welding

B1 B2 B3 B4

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Checkpoint

Voltage V

Name

T/R Voltage Switching Unit

 Fault phenomenon: High startup current and abnormal operation of the whole device

Maintenance methods:

The fault is mainly caused by the abnormal switching of the transmitting and receiving voltages, which leads to the incomplete switching of the voltages of the two circuits.

1. Disconnect the transmitting small signal line.

2. Press/ release the hand microphone PTT button, and the measurement data of each checkpoint shall be as follows:

B5 +9T Transmitting 9V voltage B6 +9R Receiving 9V voltage

 In the receiving state, +9T voltage should be about 0V;  In the transmitting state, +9T should be about 9V, and +9R

should be about 0~0.15V.

3. If the above voltage is abnormal, focus on checking whether the components in the T/R voltage switching unit are faultily welded or defective. MOS tube and diode in this unit are damaged a lot.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Checkpoint

Voltage V

Name

 Fault phenomenon: low startup current

Maintenance methods:

1. Check the model of the two regulators to prevent wrong loading of materials.

2. Check the voltage at each point:

B7 +9 Internal 9V volt a ge B8 +5 Internal 5V volt a ge

 In some cases, the low startup current is probably due to the

wrong material loading of the two regulators.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

 Fault phenomenon: there is sudden change of current when the power amplifier is adjusted to

static state

Maintenance methods:

1. First confirm that the static current does have nonlinear changes (sudden changes) during regulation.

2. Adjust all three adjustable potentiometers to zero.

3. First turn up potentiometers B10 and B11 by 650mA respectively, and observe whether the change of current is linear during adjustment.

4. Then adjust potentiometer B9 to increas e the cur rent by 350mA, and observe the change of current at any time during the adjustment. Once there is a sudden increase in current, return the potentiometer B9 to zero and adjust it again to observe whether the current changes suddenly. If it still changes suddenly, it can be determined that the power tube RD06 is damaged.  According to previous maintenance experience, most sudden

changes of current are caused by the damage of RD06.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Checkpoint

Voltage V Name

Power tube grid voltage (c ut -off

- amplification)

Power tube grid voltage (c ut -off

- amplification)

B14

13.8

Power tube VCC voltage

B15

13.8

Power tube VCC voltage

Checkpoint

Voltage V

Name

Transmitting reference

voltage

Transmitting reference

voltage

Checkpoint

Voltage V

Name

Transformer secondary

voltage

Transformer secondary

voltage

B20 13.8V

Transformer primary voltage

B21 13.8V

Voltage at the choke

 Fault phenomenon: during static current adjustment, the current does not change

1. Disconnect the transmitting small signal line and press the hand

microphone so that the whole device enters the transmitting state.

2. Check the voltage status at each point:

B12 2.5～4.55

B13

2.5～4.55

Maintenance methods:

3. If the voltage of check points B12 and B13 is 0 or lower than the above standard voltage, it indicates that there is a problem with the power tube grid power supply or there is a short circuit in the power tube grid.

3.1 Power off the whole device and unplug the power cord. Measure whether the grid of two RD16HHF1 p ower tubes is short-circuited to the ground.

3.2 Start up to enter the transmitting state, and measure whether the voltage at the following check poi nt s is normal:

B16 6

B17 6

4. If the above steps are normal, check the following points:

B18 13.8V

B19 13.8V

 If there is a point with voltage of 0 among the above check points,

check whether there is false welding at the four points.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Output transformer

 Fault phenomenon: the power supply is short-circuited as soon as the transmitting starts (the

power supply exceeds 10A)

Maintenance methods:  Power off the whole device, and check whether the winding of

the output transformer is short-circuited with the copper tube of

the transformer. This fault is generally a short circuit caused by the cutting of the winding sheath by the copper tube in the transformer during the manufacturing process of the transformer.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Setting Parameters

Parameter

Frequency

Amplitude

 Fault phenomenon: no power

1. Adopt the stage-by-stage s ignal ins pectio n method to tr oubles hoo t

such faults. The signal measurem ent at each check poi nt shall be as follows:

Name

Oscilloscope

Parameter 1 Parameter 2

Time base: 50ns

Y-axis:

0.2～20V

3

X10 gear

Connect the transmitting small signal line, connect the test hand microphone, and switch the test tooling to the transmitting state

Checkpoint

B18 14.27

B19 14.27 2.4 Preamp outp ut

B20 14.27

B21 14.27 10.2 RD06 output B22 14.27 17～18.5 RD16 input

B23 14.27

B24 14.27

MHz

Vpp

0.62 Power amplifier

1.84

118

98～100 Antenna port

Name

input signal

Three-wire

transformer output

Power amplifier

transformer output

output

Maintenance methods:

2. When the amplitude of a certain stage is significantly different from the above standard amplitude, it should be re-detected a nd positioned.

3. When no signal is detected at B18 checkpoint, it is necessary to consider whether the IPX signal line is damaged.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Comprehensive Situation

Fault Point

No voltage

The filter

Input

Output

 Fault phenomenon: no power in some frequency range (low power)

Maintenance methods:

General cause: the relay and coil of a certain filter are faulty.

1. Take the filter shown in the figure as an example, and pay attention to the input and output terminals in the figure.

2. First make sure that check point B 23 has output, w ith high ampli tude (generally above 50V).

3. Judgment in the following situations:

B23 has

signal

B23 has

signal

B23 has

signal

No signal

behind input

terminal

There is voltage on the coil in

the filter

There is

signal

behind input

terminal

B25 has no

signal Low or high

B25 has no

signal High

on the coil in

the filter

current

Low current

Input

terminal

relay is broken Output

terminal

relay is broken

coil is

broken or

faultily welded

 This fault is generally caused by relay dam age (internal contact is

damaged after wave welding), and part of i t is caus ed b y LP F coil breaking or false welding. The fault phenomenon is obvious, which can be determined one by one according to the above method.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Feedback resistor

Secondary

Primary

Input transformer

Feedback resistor

 Fault phenomenon: the power of the whole section is small (only ≤ 10W)

 Fault cause 1: this fault is generally caused by the reverse

welding of the primary and secondary coils of the input

transformer. Transformer primary (near RD06 end): 2T Transformer secondary (near RD16 end): 6T

 Fault cause 2: two feedback resistors are faultily welded or

desoldered.

Maintenance methods:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Standing wave bridge

FPC socket

 Fault phenomenon: power out of control (output exceeds 22W, and regulation is invalid)  Fault phenomenon: The standing wave of the variable capacitor cannot be adjusted to the

minimum

Maintenance methods:  Power out of control: this fault is generally caused by the false

welding of standing wave bridge unit or FPC socket unit. Check

the welding condition.

 The standing wave cannot be adjusted to 0: check whether the

variable capacitor of the standing wave bridge unit is welded well;

check whether the coil winding of the standing wave coupler is

broken.

 During the maintenance, LM358 damage is found, so pay

attention to screening.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Pin voltage

of ULN2803

Unselected

Frequency range control chip

 Fault phenomenon: when switching frequency range, LPF relay does not act

Maintenance methods:

1. The relay of e ach LP F fre quency r ange is con trolle d by the c ontrol

chip ULN2803 output .

2. Voltage of output control pin corresponding to ULN2803:

corresponding to each band output

Selected Voltage

Voltage

0.7V 13.8V

3. According to the circuit schematic diagram, measure the band voltage of the output pin respectively, to judge whether ULN2803 works normally.

4. Check whether the previous stage control chip 74HC595 of ULN2803 has poor welding.

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Fault

Phenomenon

Maintenance Method

Base board

Checkpoint

 Fault phenomenon: some sections of the transmitting spectrum are abnormal, with large stray

Maintenance methods:

Check whether there is any pin

Multi frequency

range adhesion

 All 0402 packaged chip capacitors on the B27 check point should

be carefully checked. Due to the welding of the transformer and

feedback resistor below, it is easy for this capacitor to c onnect tin,

resulting in band control disorder. This fault occurs frequently.

Check whether there is any pin

connected to tin

B27

B28

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Antenna tuner unit

 Fault phenomenon: antenna tuner failure (unable to adjust)

1. Check whether all chips, relays and coils in the antenna tuner unit

are faultily welded.

2. Confirm whether the magnetic ring and number of turns of the

antenna tuner coil are correct.

3. Check whether the transmitting static current of the power

amplifier unit is correctly adjusted.

4. Check whether the standing wave bridge is well adjusted.

Maintenance methods:

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Prepared/ Revised

Version No.

Revision Record:

by Revision Content

Yan Huan

Preparation for

the first time

V1.0/A0

Date

2022.07.27

XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver

Temporarily ended.

XieGu G90 Maintenance User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Startup failure