Miller Bobcat 225 NT - User Manual

Questions and Answers

L
Linda RamosAug 19, 2025
Why Miller Bobcat 225 NT has no weld output?
- J
  Juan BrightAug 19, 2025
  If your Miller Portable Generator isn't producing any weld output, there are several things you can check: * First, ensure all equipment is disconnected from receptacles when starting the unit. * Check the control settings and weld connections. * Inspect fuse F1 and replace it if it's open. * Also, verify the connection of plug PLG6. If these steps don't resolve the issue, it's recommended to have a Factory Authorized Service Agent inspect the brushes, slip rings, and integrated rectifier SR2.
A
Alison ScottAug 21, 2025
What to do if Miller Bobcat 225 NT engine will not start?
- L
  Laura BrewerAug 21, 2025
  If your Miller Portable Generator engine refuses to start, begin by checking the fuel and oil levels. Next, verify the battery voltage and ensure the battery connections are secure. Also, check the low oil pressure shutdown switch. If the problem persists, a Factory Authorized Service Agent should inspect the fuel shutoff solenoid FS1 (FS1 optional on Onan-powered units).
M
melissaschneiderAug 23, 2025
What to do if Miller Bobcat 225 NT Portable Generator has erratic weld output?
- J
  Jessica SullivanAug 25, 2025
  If you're experiencing erratic weld output from your Miller Portable Generator, try the following: * Check the control settings. * Ensure that connections to the electrode and workpiece are tight and clean. * Use dry, properly stored electrodes for Stick and TIG welding. * Remove excessive coils from weld cables. * Clean and tighten connections both inside and outside the welding generator. If the issue continues, have a Factory Authorized Service Agent check the brushes and slip rings.
M
Michele MartinezAug 26, 2025
How to fix low weld output on Miller Bobcat 225 NT?
- M
  Michelle BarkerAug 26, 2025
  To address low weld output on your Miller Portable Generator, start by checking fuse F1 and replace it if it's open. Also, check the control settings. It's important to check and adjust the engine speed. Additionally, service the air cleaner according to the engine manual. If the problem persists, have a Factory Authorized Service Agent check the brushes and slip rings.
M
Michael BennettAug 27, 2025
What to do if Miller Bobcat 225 NT engine will not crank?
- C
  Crystal WebsterAug 27, 2025
  If the engine of your Miller Portable Generator will not crank, start by checking fuse F6 and replace it if open. Also, check the battery voltage and ensure the battery connections are tight. Verify the connections of plug PLG4 and plug PLG8. If these steps don't resolve the issue, have a Factory Authorized Service Agent check Engine Control switch S2.
S
Susan MiddletonAug 30, 2025
What to do if Miller Portable Generator engine stopped during normal operation?
- M
  Mercedes MurphyAug 30, 2025
  If the engine of your Miller Portable Generator stops during normal operation, there are several potential causes to investigate. Begin by checking the fuel and oil levels. Also, check the low oil pressure shutdown switch. Consider periodically recharging the battery (approximately every 3 months) or replacing it if necessary. For more complex issues, have a Factory Authorized Service Agent check the fuel shutoff solenoid FS1 (FS1 optional on Onan-powered units).
J
Jennifer WilliamsSep 1, 2025
Why Miller Bobcat 225 NT battery discharges between uses?
- J
  Jaclyn JacobsSep 1, 2025
  If your Miller Portable Generator's battery discharges between uses, try cleaning the battery, terminals, and posts with a baking soda and water solution, then rinse with clear water. Also, periodically recharge the battery (approximately every 3 months), and consider replacing the battery if necessary.
J
Jessica StewartSep 3, 2025
What to do if Miller Portable Generator has no output at auxiliary power receptacles?
- M
  Mary ColeSep 3, 2025
  If your Miller Portable Generator has no output at the auxiliary power receptacles, try resetting the circuit breakers. If equipped, press the optional GFCI receptacle Reset button. Also, check fuse F1 and replace it if it is open and check plug PLG6 connection. If the issue persists, have a Factory Authorized Service Agent check the brushes, slip rings, and integrated rectifier SR2.
P
pricemichaelSep 5, 2025
Why Miller Bobcat 225 NT has erratic power output?
- M
  michaelrodriguezSep 5, 2025
  If your Miller Portable Generator exhibits erratic power output, first check the fuel level. Check and adjust the engine speed. Also, inspect the receptacle wiring and connections. If the problem persists, have a Factory Authorized Service Agent check the brushes and slip rings.
H
Heather ParkSep 7, 2025
How to fix high weld output on Miller Bobcat 225 NT Portable Generator?
- A
  Ashley CaldwellSep 7, 2025
  To correct high weld output on your Miller Portable Generator, check the control settings and check and adjust the engine speed.

Summary

Description

Features

Details the physical and functional attributes of the welding generator.

Processes

Stick (SMAW) Welding

Guidelines for performing Stick (SMAW) welding with the generator.

MIG (GMAW) Welding

Guidelines for performing MIG (GMAW) welding with the generator.

Non-Critical TIG (GTAW) Welding

Guidelines for performing non-critical TIG (GTAW) welding with the generator.

Safety Precautions

Symbol Usage

Explains safety symbols used throughout the manual.

Arc Welding Hazards

Details potential dangers associated with the arc welding process.

Engine Hazards

Outlines potential risks related to the generator's engine.

Additional Safety Hazards

Covers further installation, operation, and maintenance hazards.

Principal Safety Standards

Lists important safety standards and codes to adhere to.

EMF Information

Discusses electromagnetic fields and their potential effects.

Definitions

Symbol Definitions

Provides definitions and meanings for various symbols used in the manual.

Specifications

Weld, Power, and Engine Specifications

Details technical specs for welding modes, power output, and engines.

Dimensions, Weights, and Operating Angles

Provides physical measurements, weight, and safe operating angles.

Fuel Consumption

Shows fuel usage rates for Onan and Kohler engine models.

Duty Cycle

Explains the generator's duty cycle for welding operations.

Volt-Ampere Curves

Illustrates voltage and amperage output capabilities for different modes.

Installation

Installing Welding Generator

Guides on properly positioning and setting up the welding generator.

Engine Prestart Checks

Steps for pre-operation checks on both Onan and Kohler engines.

Connecting the Battery

Instructions for correctly connecting the unit's battery.

Installing Exhaust Pipe

Steps for installing the exhaust pipe on the generator.

Connecting to Weld Output Terminals

Details how to connect cables to the generator's output terminals.

Selecting Weld Cable Sizes

Recommendations for choosing appropriate weld cable sizes.

Operating Welding Generator

Front Panel Controls

Explains the function of all controls on the generator's front panel.

Operating Auxiliary Equipment

Standard Receptacles

Describes the standard AC power receptacles and their usage.

Optional Auxiliary Power Receptacles

Details the features of optional auxiliary power receptacle configurations.

Wiring Optional 240 Volt Plug

Provides instructions for wiring an optional 240-volt plug.

Maintenance (Onan-Powered Units)

Routine Maintenance

Outlines regular maintenance tasks for Onan-powered units.

Servicing Air Cleaner

Instructions for cleaning and servicing the air cleaner on Onan engines.

Changing Engine Oil, Oil Filter, and Fuel Filter

Step-by-step guide for oil and filter changes on Onan engines.

Adjusting Engine Speed

Instructions for setting idle and weld/power speeds for Onan engines.

Servicing Optional Spark Arrestor

Guide for inspecting and servicing the spark arrestor on Onan units.

Maintenance (Kohler-Powered Units)

Routine Maintenance

Outlines regular maintenance tasks for Kohler-powered units.

Servicing Air Cleaner

Instructions for cleaning and servicing the air cleaner on Kohler engines.

Changing Engine Oil, Oil Filter, and Fuel Filter

Step-by-step guide for oil and filter changes on Kohler engines.

Adjusting Engine Speed

Instructions for setting idle and weld/power speeds for Kohler engines.

Servicing Optional Spark Arrestor

Guide for inspecting and servicing the spark arrestor on Kohler units.

Troubleshooting

Welding Troubleshooting

Solutions for common welding output issues.

Auxiliary Power Troubleshooting

Solutions for problems with auxiliary power output.

Engine Troubleshooting

Diagnosing and resolving engine-related operational problems.

Electrical Diagrams

Circuit Diagram (Onan-Powered Units)

Detailed electrical schematic for Onan-powered generator units.

Circuit Diagram (Kohler-Powered Units)

Detailed electrical schematic for Kohler-powered generator units.

Auxiliary Power Guidelines

Selecting Equipment

Advice on selecting appropriate equipment for auxiliary power.

Grounding Generator

Instructions for grounding the generator when mounted on a vehicle or building system.

Equipment Power Requirements

Guidance on calculating power needs for various equipment.

Motor Starting Power

How to determine starting amperage requirements for motors.

Extension Cord Selection

Tables for selecting appropriate extension cords based on load and length.

Stick Welding (SMAW) Guidelines

Stick Welding Procedure

Step-by-step instructions for performing stick welding.

Electrode and Amperage Selection Chart

Chart for selecting electrodes and corresponding amperage settings.

Troubleshooting Weld Quality

Common issues like porosity, spatter, fusion, and penetration in stick welds.

MIG Welding (GMAW) Guidelines

Typical MIG Process Control Settings

Recommended settings for MIG welding parameters.

Holding And Positioning Welding Gun

Proper techniques for holding and positioning the MIG welding gun.

Troubleshooting Weld Quality

Common issues like spatter, porosity, and penetration in MIG welds.

Parts List

Main Assembly (Onan Engine)

Illustrated breakdown of the main assembly for Onan-powered units.

Front Panel Components

Lists and illustrates components on the front panel.

Generator Assembly

Illustrated breakdown of the generator assembly components.

Warranty Information

Summary

Description

Features

Details the physical and functional attributes of the welding generator.

Processes

Stick (SMAW) Welding

Guidelines for performing Stick (SMAW) welding with the generator.

MIG (GMAW) Welding

Guidelines for performing MIG (GMAW) welding with the generator.

Non-Critical TIG (GTAW) Welding

Guidelines for performing non-critical TIG (GTAW) welding with the generator.

Safety Precautions

Symbol Usage

Explains safety symbols used throughout the manual.

Arc Welding Hazards

Details potential dangers associated with the arc welding process.

Engine Hazards

Outlines potential risks related to the generator's engine.

Additional Safety Hazards

Covers further installation, operation, and maintenance hazards.

Principal Safety Standards

Lists important safety standards and codes to adhere to.

EMF Information

Discusses electromagnetic fields and their potential effects.

Definitions

Symbol Definitions

Provides definitions and meanings for various symbols used in the manual.

Specifications

Weld, Power, and Engine Specifications

Details technical specs for welding modes, power output, and engines.

Dimensions, Weights, and Operating Angles

Provides physical measurements, weight, and safe operating angles.

Fuel Consumption

Shows fuel usage rates for Onan and Kohler engine models.

Duty Cycle

Explains the generator's duty cycle for welding operations.

Volt-Ampere Curves

Illustrates voltage and amperage output capabilities for different modes.

Installation

Installing Welding Generator

Guides on properly positioning and setting up the welding generator.

Engine Prestart Checks

Steps for pre-operation checks on both Onan and Kohler engines.

Connecting the Battery

Instructions for correctly connecting the unit's battery.

Installing Exhaust Pipe

Steps for installing the exhaust pipe on the generator.

Connecting to Weld Output Terminals

Details how to connect cables to the generator's output terminals.

Selecting Weld Cable Sizes

Recommendations for choosing appropriate weld cable sizes.

Operating Welding Generator

Front Panel Controls

Explains the function of all controls on the generator's front panel.

Operating Auxiliary Equipment

Standard Receptacles

Describes the standard AC power receptacles and their usage.

Optional Auxiliary Power Receptacles

Details the features of optional auxiliary power receptacle configurations.

Wiring Optional 240 Volt Plug

Provides instructions for wiring an optional 240-volt plug.

Maintenance (Onan-Powered Units)

Routine Maintenance

Outlines regular maintenance tasks for Onan-powered units.

Servicing Air Cleaner

Instructions for cleaning and servicing the air cleaner on Onan engines.

Changing Engine Oil, Oil Filter, and Fuel Filter

Step-by-step guide for oil and filter changes on Onan engines.

Adjusting Engine Speed

Instructions for setting idle and weld/power speeds for Onan engines.

Servicing Optional Spark Arrestor

Guide for inspecting and servicing the spark arrestor on Onan units.

Maintenance (Kohler-Powered Units)

Routine Maintenance

Outlines regular maintenance tasks for Kohler-powered units.

Servicing Air Cleaner

Instructions for cleaning and servicing the air cleaner on Kohler engines.

Changing Engine Oil, Oil Filter, and Fuel Filter

Step-by-step guide for oil and filter changes on Kohler engines.

Adjusting Engine Speed

Instructions for setting idle and weld/power speeds for Kohler engines.

Servicing Optional Spark Arrestor

Guide for inspecting and servicing the spark arrestor on Kohler units.

Troubleshooting

Welding Troubleshooting

Solutions for common welding output issues.

Auxiliary Power Troubleshooting

Solutions for problems with auxiliary power output.

Engine Troubleshooting

Diagnosing and resolving engine-related operational problems.

Electrical Diagrams

Circuit Diagram (Onan-Powered Units)

Detailed electrical schematic for Onan-powered generator units.

Circuit Diagram (Kohler-Powered Units)

Detailed electrical schematic for Kohler-powered generator units.

Auxiliary Power Guidelines

Selecting Equipment

Advice on selecting appropriate equipment for auxiliary power.

Grounding Generator

Instructions for grounding the generator when mounted on a vehicle or building system.

Equipment Power Requirements

Guidance on calculating power needs for various equipment.

Motor Starting Power

How to determine starting amperage requirements for motors.

Extension Cord Selection

Tables for selecting appropriate extension cords based on load and length.

Stick Welding (SMAW) Guidelines

Stick Welding Procedure

Step-by-step instructions for performing stick welding.

Electrode and Amperage Selection Chart

Chart for selecting electrodes and corresponding amperage settings.

Troubleshooting Weld Quality

Common issues like porosity, spatter, fusion, and penetration in stick welds.

MIG Welding (GMAW) Guidelines

Typical MIG Process Control Settings

Recommended settings for MIG welding parameters.

Holding And Positioning Welding Gun

Proper techniques for holding and positioning the MIG welding gun.

Troubleshooting Weld Quality

Common issues like spatter, porosity, and penetration in MIG welds.

Parts List

Main Assembly (Onan Engine)

Illustrated breakdown of the main assembly for Onan-powered units.

Front Panel Components

Lists and illustrates components on the front panel.

Generator Assembly

Illustrated breakdown of the generator assembly components.

Warranty Information

Miller Bobcat 225 NT Specifications

General

Rated Output Power	8, 000 watts
Engine	Kohler CH730
Fuel Type	Gasoline
Fuel Tank Capacity	12 gallons
AC Output	120/240 V
DC Output	12 V
Engine Type	OHV

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Miller Bobcat 225 NT - User Manual

Table of Contents

Questions and Answers

Summary

Description

Features

Processes

Stick (SMAW) Welding

MIG (GMAW) Welding

Non-Critical TIG (GTAW) Welding

Safety Precautions

Symbol Usage

Arc Welding Hazards

Engine Hazards

Additional Safety Hazards

Principal Safety Standards

EMF Information

Definitions

Symbol Definitions

Specifications

Weld, Power, and Engine Specifications

Dimensions, Weights, and Operating Angles

Fuel Consumption

Duty Cycle

Volt-Ampere Curves

Installation

Installing Welding Generator

Engine Prestart Checks

Connecting the Battery

Installing Exhaust Pipe

Connecting to Weld Output Terminals

Selecting Weld Cable Sizes

Operating Welding Generator

Front Panel Controls

Operating Auxiliary Equipment

Standard Receptacles

Optional Auxiliary Power Receptacles

Wiring Optional 240 Volt Plug

Maintenance (Onan-Powered Units)

Routine Maintenance

Servicing Air Cleaner

Changing Engine Oil, Oil Filter, and Fuel Filter

Adjusting Engine Speed

Servicing Optional Spark Arrestor

Maintenance (Kohler-Powered Units)

Routine Maintenance

Servicing Air Cleaner

Changing Engine Oil, Oil Filter, and Fuel Filter

Adjusting Engine Speed

Servicing Optional Spark Arrestor

Troubleshooting

Welding Troubleshooting

Auxiliary Power Troubleshooting

Engine Troubleshooting

Electrical Diagrams

Circuit Diagram (Onan-Powered Units)

Circuit Diagram (Kohler-Powered Units)

Auxiliary Power Guidelines

Selecting Equipment

Grounding Generator

Equipment Power Requirements

Motor Starting Power

Extension Cord Selection

Stick Welding (SMAW) Guidelines

Stick Welding Procedure

Electrode and Amperage Selection Chart

Troubleshooting Weld Quality

MIG Welding (GMAW) Guidelines

Typical MIG Process Control Settings

Holding And Positioning Welding Gun

Troubleshooting Weld Quality

Parts List

Main Assembly (Onan Engine)

Front Panel Components

Generator Assembly

Warranty Information

Summary

Description

Features

Processes