Hobart Welding Products OM-928 specifications Troubleshooting Power Source

4-5. Troubleshooting Power Source

Is input power connected to correct line voltage?

Yes

				*
				Momentarily press torch
				trigger and listen for gas/air
No	Connect unit to proper input	Is compressor	No	valve operation. Check for
				Postflow air at torch. Check
	voltage. (see Section 2-7).
		operating?		Control board PC1, air filter,
				and gas/air connections to
				PC1 and torch.
		Yes

Is Power switch in the On position?

Yes

No	Place Power switch in the
	On position. (see Section
	3-1).

		Press torch trigger and
	No	check if pilot arc ignites.
Does pilot arc		Check torch consumables.
ignite?		*Check torch connections,
		relay CR1, gas/air system,
		and torch.
Yes

Is the cooling fan running?

Yes

	*
No	Check Power switch S1,
	relay CR2, and thermistor
	R1.

Does pilot arc

transfer to workpiece?

Yes

Place torch near workpiece and check if pilot arc “jumps”

No or transfers to workpiece.

Check work clamp connec- tion. *Check Control board PC1 and connections, and torch and its connections.

Is Power light On?

Yes

Is Trouble light On?

No

No

Yes

*

Reset Power switch S1 and verify line power voltage.

Check relay CR2, thermistor R1, and Control board PC1.

Check torch consumables. Reset Power switch S1. If unit is overheated, wait while fan cools down unit temperature.

Check all connections, Check main transformer T1, Check inductor L1. Return to beginning of chart.

*Servicing procedure to be performed only by authorized Service Station.

OM-928 Page 18