XIEGU X6100, HF Transceiver Series Manual

Device Overview

X6100 is a short-wave transceiver in a zero IF (ZIF) architecture, which adopts a HF/50 MHz full mode (for data communications) and comprises a built-in automatic antenna tuner and a built-in large-capacity lithium battery pack. The transmitting power of this device is 5W.
The block diagram of each part of the device is as follows:

Basic skills of board-level maintenance:

1. Be familiar with the circuit structure of the 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 proficiently and combine various operations to support the maintenance 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.

Next, each circuit board will be regarded as a unit to explain the judgment, detection and maintenance 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 fault on the single board and the device will be explained at the same time.

Board-level Maintenance

Antenna tuner board unit

X6100 LPF&ATU V1.2

• Fault phenomenon: no LPF in a section, no LPF in the entire section
  

Fault phenomenon	Maintenance method
	LPF antenna tuner board	Check points
No LPF in a section	Check the coil of this section for false welding	LPF
	Check the capacitor for solder bridge short circuit	Point B
No LPF in the entire section	Check 12pin cable socket for false soldering	Point C1
	Check the standing wave detector for shorted toroidal coil	Standing wave detector
	Check whether the antenna pedestal and ipx base are in good contact with the tool

• Also pay attention to the control voltage in the control section and make sure that the relay that should be open is open.

• Failure phenomenon: power runaway
  

Fault phenomenon	Maintenance method
	LPF antenna tuner board	Check points
Power runaway	Check for welding problems in the standing wave detector	Standing wave detector
	Check the FPC socket for false welding	C1
	Check the welding of the middle plate main control	MCU
	Check the FPC socket for false welding	C2

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

Maintenance methods:

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 the back of the antenna tuner board to see whether there are dropped or burned capacitor elements.

Fault phenomenon	Maintenance method
	Antenna tuner board	Check points
Antenna tuner failure	Check for welding problems between antenna tuner and control	Antenna tuner, control 1, and control 2
	Check the capacitor on the back of the antenna tuner board for burn marks or dropped parts	A

• Since the antenna tuner board requires manual cutoff of the pins that are too long, there will be the possibility that capacitors are snipped off and damaged and coils falsely soldered, resulting in the absence of LPF, anneta tuner failure, and so on.

Middle plate unit

The distribution map of middle plate "X6100 BaseUnit V1.3b" units is as above:

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

Maintenance methods:

• We are to explain with the default test frequency point of 14.270 MHz as an example. The maintenance test frequency point of each subsequent step is considered to be 14.270 MHz by default.

Measurement point	Voltage, V	Name
1		Power module
2	+5A	Utility 5V power supply
3	+3.3A	Baseband unit power supply
4	+3.3LO	Local oscillator unit power supply
5	+5R	Receiving 5V power supply
6	+5T	Transmitting 5V power supply
D2	+3.3	MCU unit power supply

• The +5T is only available in the transmitting state and is theoretically 0V in the receiving state.
• +5R is 5V in the receiving state and 0V in the transmitting state (the device is in the receiving state by default).
• +5 and 3.3V voltages are available in both the receiving and transmitting states.

Test points	Frequency, MHz	Amplitude, Vpp	Name
LO1	26.000	3.6	TXCO reference clock
LO2	14.270	5.9	Local oscillator output

• Failure phenomenon: BootLoader or firmware cannot be written
  

Maintenance methods:

Fault phenomenon	Maintenance method
	Middle plate	Check points
Unable to write BootLoader	Check for false welding	D1 & MCU chips
	Check for the presence of 3.3 V voltage	D2

• Also check for correct programmer connection

Fault phenomenon	Maintenance method
	Middle plate	Check points
Unable to write the firmware	Check for false welding	D3, D4 & MCU chips

• Note: Since the FFC cable has been plugged and unplugged many times, it may cause some FFC cable contacts to break and fall inside the FPC socket to induce a short circuit.

• Fault phenomenon: no receiving, or double peaks
  

Maintenance methods:

1. Instrument settings:

Instrument name	Instrument settings		Oscilloscope probe position
	First set of parameters	Second set of parameters
Signal source	14.271 MHz, -20 dBm	14.271 MHz, -40 dBm	/
Oscilloscope	50 ns/100 mV	1 ms/100 mV	X10

• Note: The oscilloscope must be set at position X10; the coupling method is AC coupling.

2. Check whether there is any output or abnormality of voltage at all levels as follows:

Check points	Voltage, V	Name
1 (top to bottom)	5.5, 0, 13.5, 3.3 (left to right)	Power module
2	+5	Utility 5V power supply
3	+3.3	Baseband unit power supply
4	+3.3	Local oscillator unit power supply
5	+5	Receiving 5V power supply

• Power module pin PSYNC is the power supply synchronizing signal square wave.

3. Test whether the local oscillator is working normally. The test data is roughly as follows:

Check points	Frequency, MHz	Amplitude, Vpp	Name
LO1	26.000	3.6	TXC O reference clock
LO2	14.27	5.9	Local oscillator output

• The upper end of the two resistors at check point LO2 is for the quadrature output of the local oscillator signal, with the same frequency and amplitude.

4. Measure the signal strength according to the signal routing, then measure R1, R2 and R3 in turn.
   • During the above test, PRE shall be turned on. If the value measured at a check point is not consistent with the standard value, it indicates that there may be a fault.

Check points	Frequency	Amplitude, mVpp	Instrument settings
R1	14.271 MHz	62	First set of parameters
R2	14.271 MHz	500
R3	14.271 MHz	500
R4	1 KHz	450	Second set of parameters

5. If no signal is detected at R2, there may be a problem with the BPF unit.
6. The waveforms measured at the four test points of R4 should be sine waves of the same amplitude. A multimeter can also be used to measure its DC voltage.
   • The DC voltage at four test points of R4 should be similar to the voltage at the measurement point R5. If above or below the required value, replace the corresponding tantalum capacitor.
   • A large number of bad tantalum capacitors in the previous batch cause no receiving, abnormal receiving, double peaks, and other undesirable phenomena.
7. If the above maintenance procedures are normal but there is still no receiving, the suspicion is that ADC conversion (CS4272) and MCU main control are not properly welded or any component is damaged.

• Fault phenomenon: no IO output, or IO exception
  

Maintenance methods:

1. Instrument settings: second set of parameters.
2. All four measurement points (A1, A2, B1, B2) in the left figure are sine waves with a frequency of 1 KHz.

Measurement point	Amplitude, mVpp
A1	66
A2	66
B1	450
B2	450

3. If the value measured at a check point is not consistent with the standard value, it indicates that there may be a fault.
4. If there is no problem with the above measurement points, check whether the IO holder is damaged by false welding.
   • Note: There are many bad tantalum capacitors in the previous batch.
   • The above tests are based on normal receiving.

• Fault phenomenon: BPF unit test failure
  

Maintenance methods:

1. First check the BPF band switching control area:
   • False welding, solder bridge or damage to the MCU main control on the middle plate can also result in BPF anomaly due to the lack of BPF.

Fault phenomenon	Check points
	Middle plate	Inspection area
No BPF	Check the control for parts dropped after false welding	B1, B2

2. Check in the order of A1-A2-A3-A4-A5-A6.
   • A3 and A4 are BPF input and output ports, respectively; A6 is the input port of the mixer.
     The data of each test point is shown in the table below:

Check points	Frequency, MHz	Amplitude, mVpp	Instrument settings
A1	14.271	62	Signal source	14.271 MHz, -20 dBm
A3	14.271	54
A4	14.271	40	Oscilloscope	50 ns/100 mV
A5	14.271	500

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.

• Fault phenomenon: the horn is silent
  

Maintenance methods:

1. First check whether the built-in speaker is damaged: use the test horn to access P1, and listen out for any sound.
2. Check whether there is any false welding on the S/P seat.
   • The pads of the S/P seat may be detached or fall off due to violent and frequent plugging and unplugging.
3. Turn the sound volume to 30, and make sure a sine wave signal is measured at the P2 check point of LM386 output (PIN-5):

Check points	Receiving Frequency MHz	Amplitude, mVpp	Check point frequency	Signal
P2	14.27	700	1 KHz	Standard sine wave

• Instrument settings:

Instrument settings
Signal source	14.271 MHz, -100 dBm
Oscilloscope	1 ms/200 mV

• Fault phenomenon: no PRE
  

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

1. Instrument settings:

Instrument settings
Signal source	14.271 MHz, -20d Bm
Oscilloscope	100 ns/(200 mV, 20 mV)

2. After PRE is turned on, the measured data at each check point shall be as follows:

Check points	Frequency, MHz	Amplitude, mVpp	Name
A7	14.271	40	BPF output
B	14.271	30	Amplifier input
A8	14.271	760	Amplifier output

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

Check points	DC voltage
B	1.90V
E	1.13V
A8	4.5~5V

• At the same time, check whether the PRE control signal "#PRE_EN" and AS179 controlled voltage turn normally.

• Fault phenomenon: ACC display screen T/R does not switch over, and no band voltage is found; CW transmitting power does not exist
  

Fault phenomenon: ACC display screen T/R does not switch over, and no band voltage is found
Maintenance methods:

Fault phenomenon	Maintenance method
	Check points	Middle plate
No T/R switching or band voltage	ACC unit	Check the ACC seat and nearby parts for false welding
	MCU	Check the wiring between the MCU and the ACC unit
	A1	Check whether the TR switching level is normal

• Note: the ACC interface is a four-core 3.5-mm stereo plug, which is unlike other interfaces.

Fault phenomenon: no CW transmitting power
Maintenance methods:

Fault phenomenon	Maintenance method
	Check points	Middle plate
No CW transmitting power	KEY unit	Check the KEY seat and nearby parts for false welding
	MCU	Check the wiring between the MCU and the KEY unit

• Fault phenomenon: failure to tune the quiescent current
  

Maintenance methods:

1. First check the welding of MOS tubes A and B: there is no short circuit.
2. Check whether fuse S and power inductor H are broken or burned, etc.
   • Directly measure with a multimeter via its on/off position.
3. Tune the quiescent current emission voltage:

Check points	Initial voltage V	Quiescent voltage V
Grid electrode A	0.7	1.32
Grid electrode B	2.5	3.05
Drain electrodes A and B	13	13

• If one of the voltages in the table above is incorrect, it might indicate a fault.
• +5T must have a 5V output during transmitting.

4. If the grid electrode voltage cannot be increased to the desired value or remains the same when MOS tubes A and B are used to tune the quiescent current, check whether the DAC conversion chip at point C is falsely welded or damaged.
   • Tune the quiescent current: that is, increase the grid electrode voltages of MOS tubes A and B so that they can work in the amplifier region.

• Fault phenomenon: no transmitting power
  

Maintenance methods:

1. First check whether the quiescent current is correct.
2. Instrument settings:

Instrument name	Instrument settings		Oscilloscope probe position
	Group 1	Group 2
Function signal generator	Frequency: 1 KHz; amplitude: 180 mV		/
Oscilloscope	1 ms/100 mV	100 ns/5 V	X10

3. Check the microphone network interface for false welding.
4. The test point data of 5w transmitting are as follows (standard sine wave):

Check points	Amplitude	Instrument settings
P1	260 mV	Group 1
Primary input	330 mV
Primary output	600 mV
Final output	13.6V	Group 2
Transformer output	33V

5. If no waveform is detected at P1, please check the backside:
   1. Baseband unit;
   2. Check the transmitting small signal unit for false welding or dropping parts.
6. If there is a signal at the output of the final amplifier and no signal at the output of the transformer, check whether the transformer is properly welded and connected and whether the coil is broken.
7. The transmitting voltage regulator (+5T) must have 5V outputs.
8. Check whether the transceiver switching relay is working normally.

• Fault phenomenon: the microphone cannot switch the frequency range, and signals are emitted once the microphone is plugged in.
  

Maintenance methods:

Fault phenomenon	Maintenance method
	Middle plate	Check points
The microphone won't switch frequency ranges and it emits signals once plugged in	Check for welding problems around the network interface pin	MIC
	Check the main control for false welding or solder bridge	MCU chip
	Check whether the microphone power supply terminal voltage is 8V	VH

• Check point A on the backside for burned parts that have fallen out.
• Check whether the elastic contacts in the RJ45 pedestal are in good condition, and whether there is deformation or dislocation.
• There are a lot of MCU main control pin solder bridges in the previous batch.

• Fault phenomenon: transmitting carrier suppression cannot be regulated
  

Maintenance methods:

• Cause 1: Carrier suppression caused by transmission channel fault cannot be adjusted. Check whether the transmitting baseband amplifier, transmitting mixer and small transmitting transformer have welding problems such as false welding and short circuit (see the picture on the left: Baseband unit, transmitting small signal area).
  • B5F has had a large number of dropped parts and broken wires, which needs to be watched out for.

• Fault phenomenon: high leakage current
  

Maintenance methods:

1. First check whether the green fuse and power protection diode in the red box in the picture on the left side are damaged and burned out.
2. Check battery charging and discharging for any severely burnt elements.
3. Conduct power-on test by using thermal imaging to see which part of the board is abnormally hot, that is, to locate the fault point.

• Fault phenomenon: the battery won't charge.
  

Maintenance methods:

Fault phenomenon	Maintenance method
	Middle plate	Check points
The battery won't charge	Check for any damage caused to the VEXT input protection diode	B2
	heck the charging module for burned or damaged parts	B3
	Observe whether the transistor is reversely welded	B1

If no problems are found, check the charging control voltage:

Check points	Charging voltage V	Charging-off voltage V
A1	3.28	0
A2	0	0.68
A3	6.23	0

Control board unit

The distribution map of control board "X6100 BaseUnit V1.3b" units is as above:

• Fault phenomenon: the yellow-green LED does not light up or is too bright
  

Maintenance methods:

1. Check whether the LED light comes off or damaged
   • Method: measure the LED with a multimeter while setting the multimeter in the diode position: if intact, the LED will light up.
2. Check for false welding, warping or reverse welding
   • The side where there is a green dot on the LED is negative.
3. Check to see whether the resistor in the red box in the picture above is partially fallen, falsely welded or damaged.

• Fault phenomenon: the key is unresponsive or garbled
  

Maintenance methods:

1. If a single key does not function, then check whether the key is damaged and poorly welded
   • Method: check the two pins of the key via the on-off position (gear) of the multimeter buzzer. Press the key to see whether the buzzer rings (if it rings, the key is in good condition).

Check points

Key 1, 2, and 3

Core board

2. If more than one key is not responsive and garbled, check whether the core board pin is short-circuited
   • Note: solder bridges are found in the previous batches of core boards.
   • Check the core board for a short circuit: make the multimeter in the on/off position to measure the two adjacent pins of core board.
3. Check whether the connection from the key to the core board is broken (PCB line breakage)

• Fault phenomenon: the knob is unresponsive or garbled
  

Maintenance methods:

1. Check points A1, A2 for dropping parts or false welding and solder bridges.

Check points

A1

A2

Core board

2. Check whether the encoder is damaged, and at points A1, A2 the three pins of the encoder cannot be mutually short-circuited.
3. Check the resistor-capacitor at points A1, A2 for damage.
4. Check whether the line connected to the core board is smooth.
5. Check the core board for solder bridges.

• Fault phenomenon: the power indicator is not working or fails to display the right color
  

Maintenance methods:

1. Observe the component in the red box in the picture on the left side to see whether they are burned or falsely welded.
2. Check the bi-colored LED light for damage using a multimeter
   • The bi-colored LED light used there is common anode (3)
3. The working voltage at each test point is as follows:

Check points	Receiving (green light) V	Transmitting (red light) V
1	2.72	0
2	3.37	4
3	5.4
4	4	3.5
5	0	2.79

• Fault phenomenon: Wi-Fi is unavailable, and it goes into a black screen once the Wi-Fi is connected
  

Maintenance methods:

1. Visual inspection: check the Bluetooth module for dropped or broken parts.
2. Check whether the line between B1 and B2 is smooth and intact.
3. Check the core board for solder bridges.
4. Check Bluetooth Wi-Fi module power supply:

Check points	Voltage (V) before Wi-Fi connection	Voltage (V) after Wi-Fi connection
1(WIFI_EN)	3.3	0
2(VCC)	3.3	3.3
3	0	3.3

• Fault phenomenon: the key light is on, but the screen does not light up or i s blurred
  

Maintenance methods:

1. 4" color screen power supply module (brightness from level 1 to level 10):
2. If VLED+ output voltage is 30V, it means that the SY7200A chip has entered the over-voltage protection state, which may be resulted from the false welding or solder bridge of the FPC socket at P1.
3. Check the welding of the FPC socket at P1 and check whether the core board has any solder bridge.
   • After the FPC cable socket is patch-welded, it must be cleaned with board washing water to remove soldering flux, which will lead to loose contact.

Check points	Voltage, V
VCC - LED	3.0
VIN	4.59~4.48
VLED+	10.4~12.4
VLED-	0~0.25

• Fault phenomenon: failure to write any program
  

Maintenance methods:

1. First check whether any parts are burned down at power supply C and D.
   • At point D, many tantalum capacitors were previously found to have been burnt out, making it impossible to write any program.
2. Check whether the power on/off key is damaged or falsely welded.
3. Check the welding at point A and B.
4. Check whether the TF card slot is intact and elastic.
5. Check the core board for solder bridges.

• Fault phenomenon: DEP port and HOST are out of order
  

Maintenance methods:

1. Fault phenomenon: DEP is without a port and HOST cursor mouse is dead
   • Patch-weld the two type-c interfaces
2. Fault phenomenon: DEV port is without a USB port or sound card
   • Patch-weld GL850G (4-port standard USB hub control)

• Fault phenomenon: the middle plate did not start (display IDLE)
  

Maintenance methods:

1. Visual inspection: check whether the FPC socket in the red box in the picture on the left side is damaged due to violent or improper plugging or poorly connected (also check whether the cable on the middle plate is properly connected).
2. Patch-weld the FPC cable socket
   • Do not connect the cable during repair welding, and be sure to remove all the flux after welding.
3. Check whether the resistor in the red box is damaged.
4. Check whether the core board has any solder bridges.

• Fault phenomenon: failure to save time settings
  

Maintenance methods:

1. Check whether the button cell is inserted obliquely and whether P1 plug is damaged.
2. Use a multimeter to check the level of the button cell (about 3.3V).
3. Check the connection of cables P2 and P3.
4. Patch-weld cables P2 and P3.
5. If the above steps failed to solve the problem, check point T for damage or false welding.

End.

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