J. Background Relay Test

This procedure tests the internal dc background current source.

1.When the repeating test displays are shown (see Sec- tion 7-2C), press Right/Increase or Left/Decrease until the display shows:

L. Arc Starter Relay Test

This procedure tests the arc starter relay. Indirectly, the Arc Starter Board PC8 is also tested.

1.When the repeating test displays are shown (see Sec- tion 7-2C), press Right/Increase or Left/Decrease until the display shows:

B A C K G R O U N D

R E L A Y T E S T

A R C S T A R T E R

R E L A Y T E S T

2.Press Parameter Select to begin the test. This ener- gizes the background relay. The display shows:

C H E C K V O L T M E T E R F O R

4 2 T O 5 4 V O L T S D C

2.Press Parameter Select to energize the arc starter relay. The display shows:

A R C S T A R T E R R E L A Y

I S E N E R G I Z E D

3.The Voltage meter on the control unit should indicate a voltage within the specified range.

If an acceptable voltage is not indicated, contact the nearest Factory Authorized Service Station/Service Distributor.

4.When the background relay tests okay, press Parame- ter Select to deenergize the relay and exit the test. Use the Right/Increase or Left/Decrease push button to ac- cess another test, or stop the diagnostics program.

K.Gas Solenoid Relay Test

This procedure tests the gas solenoid relay. Indirectly, the gas solenoid is also tested.

1.When the repeating test displays are shown (see Sec- tion 7-2C), press Right/Increase or Left/Decrease until the display shows:

G A S S O L E N O I D

R E L A Y T E S T

2.Press Parameter Select to energize the gas solenoid relay. The display shows:

G A S S O L E N O I D R E L A Y I S E N E R G I Z E D

3.If gas flows, the gas solenoid relay and gas solenoid are working correctly. In this case, go to Step 4.

If gas does not flow, contact the nearest Factory Autho- rized Service Station/Service Distributor.

4.When the gas solenoid relay tests okay, press Parame- ter Select again to deenergize the relay. The program automatically returns to the repeating test displays. Use the Right/Increase or Left/Decrease push button to access another test, or stop the diagnostics pro- gram.

3.If a crackling sound can be heard inside the welding power source, the relay is working correctly. In this case, go to Step 4.

If a crackling sound is not heard inside the welding power source, contact the nearest Factory Authorized Service Station/Service Distributor.

4.When the relay tests okay, press Parameter Select again to deenergize the relay. The program automati- cally returns to the repeating test displays. Use the Right/Increase or Left/Decrease push button to access another test, or stop the diagnostics program.

M.User Relays

This procedure tests the user relays (see Section 2-3). Since the procedure is the same for each of the user relays, one ex- ample is presented that applies to all the user relays.

1.When the repeating test displays are shown (see Sec- tion 7-2C), press Right/Increase or Left/Decrease until the display shows the test display for the desired relay.

For example, if the initial time relay is being tested, the display would show:

I N I T I A L T I M E

R E L A Y T E S T

2.Press Parameter Select to begin the test. The display shows:

I N I T I A L T I M E R E L A Y

I S E N E R G I Z E D

After a short pause, the relay energizes.

3.Use a suitable VOM (volt-ohmmeter) to check the re- sistance across the relay terminals as shown in Figure 7-1.

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Miller Electric OM-842 manual Background Relay Test, Arc Starter Relay Test, Gas Solenoid Relay Test, User Relays
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OM-842 specifications

The Miller Electric OM-842 is a versatile and powerful multi-process welding machine designed for professional welders who demand efficiency and reliability on the job. This industrial-grade welder is capable of handling various welding processes, including MIG, TIG, stick, and flux-cored welding, making it an ideal choice for a wide range of applications.

One of the standout features of the OM-842 is its robust output capability. With a maximum output of 400 amps, it can tackle thick materials with ease while maintaining exceptional arc stability. This output range allows for adaptability in different welding scenarios, whether working on heavy fabrication projects or lighter home repairs.

The OM-842 is also equipped with advanced inverter technology. This technology enhances the machine's efficiency and reduces energy consumption. Inverter machines are known for their lightweight design compared to traditional transformer welders, which makes the OM-842 more portable and easier to transport between job sites.

User-friendliness is paramount in the design of the OM-842. Its intuitive control panel features a digital display that provides real-time information on parameters such as voltage and amperage. This allows users to make quick and precise adjustments on the fly, enhancing productivity and ensuring optimal welding results.

Additionally, the OM-842 offers sophisticated weld control features, such as Auto-Set, which simplifies the setup process for beginners and experienced users alike. This technology automatically selects optimal parameters based on the material type and thickness, minimizing trial and error during welding.

The machine also includes a durable and rugged design, suitable for tough working conditions. The protective case and high-quality components ensure longevity and reliability even in adverse environments.

Safety is another critical aspect of the OM-842, with features such as over-temperature protection and a built-in fan to prevent overheating during extended use.

With its powerful performance, advanced technology, and robust design, the Miller Electric OM-842 stands out as an exceptional choice for welders seeking reliability and versatility in their welding operations, ultimately creating high-quality welds across various applications. Whether in a shop or on a construction site, the OM-842 is engineered to deliver outstanding results every time.
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