Thermal Arc ARCMASTER 400TS

Questions and Answers

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Bradley KerrAug 21, 2025
What to do if my Thermal Arc Inverter electrode melts or oxidizes when an arc is struck?
- W
  Wesley BarnesAug 21, 2025
  If the electrode melts or oxidizes when striking an arc, several factors could be at play. First, ensure gas is flowing to the welding region and that there are no kinks or breaks in the gas lines, and that the gas cylinder isn't empty. Next, check if the torch is clogged with dust and clean it if necessary. If the gas hose is cut, replace it. Impurities in the gas passage can also cause this issue; disconnect the gas hose from the torch, raise the gas pressure, and blow out any impurities. Also, verify that the gas regulator and torch valve are turned on. The electrode might be too small for the welding current; increase the electrode diameter or reduce the welding current. Finally, if the WAVE BALANCE is set above 50%, reduce it to below 50% or increase the electrode size.
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Matthew PowellSep 2, 2025
Why does my Thermal Arc Inverter have excessive bead build-up or poor penetration or poor fusion at edges of weld?
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  rayjulieSep 2, 2025
  Excessive bead build-up, poor penetration, or poor fusion at the edges of the weld when using your Thermal Arc Inverter could be because the welding current is too low. Increase the weld current and ensure proper joint preparation.
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Joshua MckinneySep 1, 2025
What to do if my Thermal Arc Inverter gas flow won't shut off?
- R
  ryanfranciscoSep 1, 2025
  If the gas flow won't shut off, it could be due to several reasons. If the weld mode (STD, SLOPE, REPEAT, or SPOT) was changed before the POST-FLOW gas time had finished, strike an arc to complete the weld cycle or switch the machine off then on to reset the solenoid valve sequence. Also, the POST-FLOW control might be set to 60 seconds; reduce the POST-FLOW time.
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dominguezrobinAug 30, 2025
Why does my Thermal Arc Inverter have a poor weld finish?
- K
  kimberlymosleyAug 30, 2025
  A poor weld finish on your Thermal Arc Inverter is often due to inadequate shielding gas. To resolve this, increase the gas flow or check the gas line for any problems that might be restricting gas flow.
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Melody ParsonsAug 29, 2025
Why is there no gas flow when the torch trigger switch is depressed on my Thermal Arc Inverter?
- S
  Sandra NixonAug 29, 2025
  If there's no gas flow when the torch trigger is depressed, several issues could be the cause. Check if the gas hose is cut and replace it if necessary. Impurities in the gas passage can also be a problem; disconnect the gas hose from the rear of the Power Source, then raise the gas pressure and blow out any impurities. Ensure the gas regulator is turned on. Finally, the torch trigger switch lead might be disconnected, or the switch/cable could be faulty; reconnect the lead or repair the faulty switch/cable.
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snyderomarAug 27, 2025
What to do if my Thermal Arc Inverter welding arc can not be established?
- R
  rsimmonsAug 27, 2025
  If a welding arc cannot be established, first ensure that the work clamp is properly connected to the workpiece, or that the work/torch leads are connected to the correct welding terminals. If using a torch lead, connect it to the '–' terminal. Finally, check the gas flow rate, ensure the cylinder isn't empty, and verify that the torch valve is on. Select the right flow rate, change cylinders or turn torch valve on.
J
Jenna WilliamsAug 26, 2025
What to do if my Thermal Arc Inverter electrode melts when arc is struck?
- H
  Haley MccoyAug 27, 2025
  If the electrode melts when the arc is struck, it could be due to two main reasons. First, check if the electrode is connected to the '+' terminal and connect it to the '–' terminal instead. Second, if the WAVE BALANCE is greater than 50%, reduce it to below 50% or increase the electrode size.
M
Michelle AlexanderAug 25, 2025
Why does my Thermal Arc Inverter have gas pockets or voids in weld metal (Porosity)?
- G
  George Haynes MDAug 25, 2025
  Porosity, or gas pockets in the weld metal, can occur for a few reasons. The electrodes might be damp; dry them before use. The welding current could be too high; reduce it. Also, surface impurities like oil, grease, or paint can cause this; clean the joint before welding.
P
Patricia BrennanAug 23, 2025
What to do if my Thermal Arc Inverter welding current reduces when welding?
- J
  James SmithAug 23, 2025
  If the welding current reduces during welding, first, check and tighten all welding cable connections. Ensure you are using the proper size and type of cable. Also, replace the electrode if it is in poor condition and verify the output torch connections to confirm correct welding polarity.

Summary

Safety Instructions and Warnings

Arc Welding Hazards

Electrical shock hazards, arc rays, fumes, and fire risks associated with arc welding.

Principal Safety Standards

Lists key safety standards and regulations for welding operations and equipment.

Introduction

How To Use This Manual

Explains how to navigate and use the service manual effectively.

Equipment Identification

Details how to identify the welding unit by its specifications and serial numbers.

Symbol Chart

Provides a reference for symbols used on the model's controls and displays.

Description

Describes the features and capabilities of the ARC MASTER welder models.

Functional Block Diagrams

Illustrates the internal workings and connections of the power supply units.

Transporting Methods

Provides instructions and safety precautions for moving the welding equipment.

Installation

Environment

Details suitable and adverse environmental conditions for operation.

Location

Guidelines for placing the welder for proper ventilation and cooling.

Electrical Input Connections

Instructions for connecting the power source to the electrical supply.

Electrical Input Requirement

Specifies the required AC power supply voltage and frequency.

Input Power

Explains the INRUSH circuit and input voltage sensing for power activation.

High Frequency Introduction (300;400 TS only)

Importance of correct installation for high frequency welding.

High Frequency Interference (300;400 TS only)

Ways interference is transmitted and how to mitigate it.

Duty Cycle

Defines duty cycle and its impact on welder performance and lifespan.

Specifications

Provides technical specifications for the welder models.

Operator Controls

ARC MASTER 300;400 TS and 300;400 S Controls Overview

Overview of front panel controls, including knob, remote socket, and terminals.

Weld Process Selection

Table explaining selection of STICK, HF TIG, LIFT TIG modes and their descriptions.

Weld Parameter Descriptions

Explanation of parameters like PRE-FLOW, HOT START, WELD CUR, and PULSE settings.

Weld Parameters and Settings

Tables detailing parameter ranges and settings for different welding modes.

Power Source Features

Details features like digital meter, fan control, VRD, and control knob.

Set-Up for SMAW (Stick) and GTAW (TIG)

Conventional Operating Procedures

Connecting work lead and electrode, adjusting current based on electrode type.

Pre-Connection Safety Warnings

Ensure power is OFF before connecting clamp; remove packaging and do not block vents.

Sequence of Operation

Control Interface Overview

Overview of controls like Pulse, Remote Current, TIG Modes, LED display, Save/Load, knob, Process, Scroll Buttons, Contactor.

Stick Welding Procedure

Step-by-step guide for performing stick welding operations.

HF TIG Welding Procedure (300;400 TS only)

Procedure for performing High Frequency TIG welding.

Lift TIG Welding Procedure

Procedure for performing Lift TIG welding.

Slope Mode Sequence (300;400 TS only)

Sequence of operations for slope mode welding.

Slope Mode with Repeat Sequence (300;400 TS only)

Operation of the repeat function during the down slope cycle.

Pulse Controls (300;400 TS only)

Controls for managing heat input in pulse welding.

Routine Maintenance

Maintenance Precautions

Disconnect power before opening; avoid blowing air into the unit during cleaning.

Basic Troubleshooting

TIG Welding Problems

Common TIG welding issues, possible causes, and remedies.

Stick Welding Problems

Common stick welding issues, possible causes, and remedies.

Power Source Problems

Troubleshooting issues related to the power source itself.

Voltage Reduction Device (VRD)

VRD Specifications

Specifications and requirements for the Voltage Reduction Device.

VRD Maintenance and Testing

Routine inspection and periodic testing procedures for the VRD.

Switching VRD On;Off

Procedure for turning the VRD function on and off.

Power Source Error Codes

E01 Over-Temperature at Primary Side

Over-temperature condition detected on the primary IGBT.

E02 Over-Temperature at Secondary Side

Over-temperature condition detected on the secondary IGBT and diode.

E03 Transformer Over-Current Failure

Excessive current detected flowing into the primary side of the main transformer.

E04 Torch Cable Failure

Error related to combined length of torch and work cables being too long.

E11 Main Supply Over Voltage

Main supply voltage exceeds specified limits (over voltage).

E12 Main Supply Under Voltage

Main supply voltage is below specified limits (under voltage).

E81 Wrong Main Supply Voltage

Error indicating incorrect main supply voltage connection.

E82 Rated Voltage Selection Circuit Abnormality

Abnormality in the rated voltage selection circuitry.

E83 Abnormalities in Mains Supply Voltage Detection

Abnormalities detected in the mains supply voltage detection circuit.

E85 Pre-charge Abnormality

Primary capacitors are not charging correctly.

E94 Thermistor Malfunction

Thermistors for component temperature detection malfunctioned.

E99 Initial Power Receiving

Error when initial AC power signal is not received by the CPU.

Failures Without Indication Codes

Troubleshooting procedures for issues without specific error codes.

Advanced Troubleshooting

System-Level Fault Isolation

Isolating defective internal subassemblies when basic troubleshooting fails.

Opening the Enclosure

Steps to safely open the unit for inspection and repair.

Verification and Remedy for Indicated Error Codes

Procedures for verifying and resolving specific error codes.

Failures Without Indication Codes

Troubleshooting procedures for issues without specific error codes.

Fault Isolation Tests and Preparation

Tests to isolate faults and preparation steps required.

Verification of Power Input Circuitry

Verifying AC input voltage and rectified output voltage.

Verification of Cooling Fan, FAN1, Drive Circuitry

Verifying cooling fan operation and its drive circuitry.

Verification of Gas Valve, SOL1, Drive Circuitry

Verifying gas valve operation and its drive circuitry.

Verification of Primary and Secondary Diodes;IGBTs

Verifying characteristics of primary/secondary diodes and IGBTs.

Verification of No-load Voltage (OCV)

Verifying no-load voltage in STICK and HF TIG modes.

Maintenance

Maintenance List

Lists maintenance items and their reference pages for components.

Service Tools and Notes

Lists required tools, parts, and notes for disassembly and assembly.

Replacement Procedures

Step-by-step guides for replacing various components like PCBs and diodes.

Parts List

Equipment Identification for Parts Ordering

Information needed to identify equipment for ordering parts.

How to Use This Parts List

Explanation of how to navigate and utilize the parts list and illustration.

Connection Wiring Guide

PCB Connection Mapping

Table mapping PCB connections to their destinations for wiring.

Interconnect Diagram

300;400 TS Interconnect Diagram

Diagram showing electrical connections within the 300/400TS model.

300;400 S Interconnect Diagram

Diagram showing electrical connections within the 300/400S model.

Diode Testing Basics

Diode Testing Procedure

Basic principles for testing diodes using a digital volt/ohm meter.

Limited Warranty

Warranty Terms and Conditions

Details warranty coverage, limitations, and exclusions for Thermal Arc products.

Warranty Schedule

Warranty Periods by Product Type

Table outlining warranty periods and labor coverage for different welder types.