How to troubleshoot a faulty TIG welding machine?

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I. The power switch is turned on, but the indicator light does not light up, the fan does not rotate, and there is no response when pressing the switch on the welding gun. 1. Is the external power supply functioning properly? 2. Is the power cable broken, or are the connections in good condition? 3. Is the power switch damaged? Solution: 1. Check the external 220V/AC voltage; 2. Check the connectors; 3. Replace it. II. The indicator light comes on when the power switch of the TIG welding machine is turned on, the fan does not rotate or stops after rotating a few times, and there is no response when the welding torch switch is pressed. 1. The connection cable between the power switch and the circuit board is not properly plugged in; 2. The supply voltage is too high or too low, triggering overvoltage protection; 3. The power input cable is too thin or too long, resulting in unstable voltage and thus overvoltage protection; 4. The 24V/30A relay in the main circuit of the motherboard does not function properly, or the resistance value of the degaussing resistor or thermistor has increased; 5. The auxiliary power supply on the motherboard is damaged, with no DC24V output; 6. Repeated switching during the wave loss period causes the start-up resistor to overheat. Solutions: 1. Check the plug connection; 2. Verify that the voltage is 380V – if the grid voltage is too low, the auxiliary power supply will not function; 3. Use thicker power cables; 4. Inspect and replace the components; 5. Repair or replace them; 6. Shut down the device for 3 minutes. III. The power-on indicator light is on, the fan is rotating, but pressing the welder switch yields no response. 1. The welder switch or its control cable is loose; 2. The aviation socket has poor contact or the connection cable is loose; 3. Check whether the rectifier and filter on the chassis are functioning properly, whether the main circuit relay is activated, and whether there is a DC 307V output. 4. The auxiliary power supply is damaged. 5. Open circuit in the silicon bridge. 6. Inspection and replacement; 4. When the machine is turned on, gas is supplied when the welding gun switch is pressed, the red light does not turn on, and there is no high-frequency output (first, check the output terminal of the welder to see if there is a DC55V voltage under no-load conditions; if DC55V is present and arc formation is possible, then the high-frequency arc generation mechanism should be checked carefully). ) First, check the output terminal of the TIG welding machine. Unplug the high-frequency control cable and see if there is a DC55V no-load voltage. If DC55V is present, plug the cable back in to see if arcing can occur. Special attention should be paid to the high-frequency arc-starting components: 1. Check whether the connection wires between the upper plate and the lower plate’s step-up transformer are loose or disconnected, and whether the transformer is open-circuited; 2. Check whether the high-voltage silicon elements and the high-voltage output capacitors 102/10K are damaged due to breakdown; 3. Check whether the high-voltage discharge nozzle is stuck, has an excessive gap, or its surface is severely oxidized; 4. Check whether the high-frequency arc starter or its connection wires are loose; 5. Check whether the high-frequency control relay is damaged and whether its power supply circuit is functioning properly; 6. Check whether the switch with the ARC/TIG conversion function is working correctly. If no DC55V is output, check whether the inverter circuit is operating properly: ① Check whether the control module is generating drive signals; ② Check whether the drive conversion and drive modules are functioning properly; ③ Check whether the field transistors, the main transformer, and the main current connection wires are loose or disconnected. Solutions: 1. Inspect and replace; 2. Adjust and replace.
V. The power-on indicator light of the TIG welder is on, the fan is running, gas is emitted when the welding torch switch is pressed, and the red light is on.
1. Overcurrent protection during operation.
2. It may be a fault in the inverter circuit or the arc-starting board. (After turning off the machine, unplug the power supply connector of the arc-starting transformer on the MOS board (located near the fan VH-03), then turn on the machine and press the welding torch switch.) a. If the red light does not turn on, it is due to a short circuit in the arc-starting transformer, or it could be caused by overvoltage during arc starting or by a broken diode. b. If the red light is on, there is a problem with the inverter circuit; shut down the device, remove the mid-board transformer and the power plug (near the fan VH-07), then turn it on again and press the welder switch. c. If the red light is on, it indicates that a certain field-effect transistor on the inverter board is damaged; at the same time, it is necessary to check whether there are any damaged components in the drive module. d. If the red light does not illuminate, it indicates a short circuit in the medium-tension transformer or the rectifier tubes; the inductance and Q value of the transformer can be measured using a bridge. C=0.9-1.6mh, Q>35: Check and replace each rectifier tube one by one. Solutions: 1. Shut down the device for 5 minutes and then restart it; 2. Stop operating it for 5 minutes; 3. a. Replace it; b. Check and replace it; d. If it is too small, replace it. VI. The device starts up normally and can generate an arc, but the weld spots turn black. 1. Check whether the solenoid valve and its air pipes are blocked by foreign objects; 2. The solenoid valve is damaged; 3. The power supply control circuit for the solenoid valve is damaged; 4. Disassemble the welding gun and the air-electric connectors, then press the switch on the welding gun – if air is released, then the welding gun is damaged; 5. The welding gun’s cable has poor current-conducting capabilities, resulting in arc scattering or deviation; 6. The quality of the tungsten tip is poor, or the argon gas is impure. Solutions: 1. Clean it. 2. Replace it. 3. Inspect and replace it. VII. Unstable and uncontrollable welding current in the TIG welder, with fluctuations in voltage. 1. Poor contact or damage to the potentiometer; 2. Leakage or damage to the filter capacitor on the base plate; 3. The remote control switch is set in the remote position; 4. Excessively long or thin input or output cables causing unstable current; 5. Poor contact or disconnection of the connectors. Solution: 1. Check and replace; 2. Place in the correct position; 3. Increase the wire cross-section; 4. Check and replace. VIII. Tripping upon startup: 1. Short circuit in the rectifier silicon bridge; 2. Loose power cable causing a short circuit. Solution: 1. Replace; 2. Insert properly. 9. When the welding gun switch is activated, the gas valve shuts off immediately, with no delay; the wave sealing is slow. The supply diode IN4004 of the gas valve control relay is short-circuited – it should be inspected and replaced. X. When the welding gun switch is pressed, there is a high-frequency discharge sound but no welding output. 1. The grounding wire of the welding gun is poorly connected or disconnected; 2. The grounding wire outlet and the internal connections of the gas-electric connector are loose, or the connection to the middle plate is broken. Solve; 3. Check and replace. XI. Poor arc starting in the TIG welder: 1. Excessive or insufficient gap between the electrodes, or oxidation of their surfaces; 2. Low capacity of the high-voltage output capacitor, along with high-voltage short circuits; 3. Incorrect turn ratio of the arc starter or leakage current between turns; 4. Poor quality of the argon gas or poor quality of the tungsten electrode; 5. Loose connections in the welding torch. Solution: 1. Clean and adjust; 2. Inspect and replace. XII. The device starts up normally, but the red light turns on as soon as it begins to operate: 1. The feedback circuit is open; 2. There is a poor connection in the main current transmission circuit or in the power components, resulting in overcurrent protection. Solution: 1. Check the connection; 2. Check and replace it. 13. High-frequency noise when turning on: 1. The manual switch controlling the optocoupler PC817 (or transistor 8050) is damaged; 2. There is a short circuit in the welding torch switch or its control wires. Solution: 1. Check and replace; 2. Check. 14. Continuous high-frequency noise during TIG welding: 1. Damaged high-frequency control relay; 2. Spikes in the output voltage; 3. High-frequency self-locking. Solution: 1. Replace it. 2. Tighten the feedback and control wires. 3. Increase the absorption of high-frequency transformers; increase the capacitance at the ends of the coils in high-frequency relays. 15. When the switch on the TIG welding machine’s torch is activated, an abnormal indicator light comes on. 1. It could be due to overheat protection; 2. It might be a fault in the inverter circuit or the arc-starting plate. ① Turn off the machine and unplug the power connector of the arc-starting transformer (VH-03, located near the fan). Restart the machine – if the red light does not come on, then there is a short circuit between the wires of the arc-starting transformer. ② If the red light is on, it indicates a fault in the inverter circuit. If there are two inverters, turn off the system first, then disconnect the power supply to one of the inverters (the VH-07 plug located near the fan). Turn the system back on and press the welder switch; if the red light does not turn off, the fault lies in the inverter whose power supply has been disconnected, while if the red light remains on, the fault is in the inverter whose power supply has not been disconnected. ③ Turn off the device and plug in the power connector of the faulty inverter; then remove the power connector of the middle board transformer (VH-07, located near the fan). Turn the device on and press the welder switch – if the red light comes on, it indicates that one of the field transistors on the MOS board is damaged. At the same time, check whether there are any damaged components in the drive module. ④ If the red light does not illuminate, the fault lies in the intermediate-board transformer and rectifier tubes; a. The inductance and Q-value of the transformer can be measured using a bridge. TIG250: L=1.2-1.6mh, Q>35; TIG400: L=1.2-2.0mh, Q>35. b. The rectifier tubes need to be checked and replaced one by one. For the function keys of the TIG250, 315P, and 400P panels, refer to the user manual; if only one key is malfunctioning, replace that specific key, while if multiple keys are faulty, replace the control panel. For other issues, refer to the examples mentioned above. Solutions: 1. Stop the device from working for 5 minutes; 2. Shut it down for 5 minutes and then turn it back on; or replace it.