Miller Electric OM-494 manual Troubleshooting, Welding

8-11. Troubleshooting

A. Welding

Trouble	Remedy
No weld output on either side; generator	Place Output (Contactor) switches in On (Hot) position, or place switches in Remote position and connect
power output okay at ac receptacles.	remote contactors to remote receptacles RC8 and RC9 (see Section 6-3).
	Unit overheated (High Temp. Shutdown light goes on); wait several minutes for thermostat(s) TP3 and
	TP4 to reset (see Section 8-10).
	Check position of Process Selector switches and Welder Selector switch. All weld output stops if
	either Process Selector switch is placed in CV position when Welder Selector switch is in Welder B
	position (see Sections 6-1and 6-3).
	Check fuse F2, and replace if open (see Section 8-10). Have Factory Authorized Service Agent
	check field current regulator board PC4.
	Have Factory Authorized Service Agent check field current regulator board PC4 and Welder Selector
	switch S2.
No weld output on either side and no	Disconnect equipment from generator power receptacles during start-up.
generator power output at ac recep-
tacles.
	Check fuse F1, and replace if open (see Section 8-10).
	Reset circuit breakers CB7 and/or CB8 (see Section 8-10).
	Have Factory Authorized Service Agent check brushes and slip rings, field excitation circuit, rotor, stator,
	and field current regulator board PC4.
No Welder A (left) weld output; Welder B	Check fuse F3, and replace if open (see Section 8-10).
(right) weld output okay.
	Check position of Welder Selector switch. Welder A (left) weld output stops when Welder Selector
	switch is placed in Welder B position (see Section 6-1).
	Unit overheated (High Temp. Shutdown light goes on); wait several minutes for thermostat(s) TP3 to
	reset (see Section 8-10).
	Have Factory Authorized Service Agent check Welder A (left) contactor circuit.
No Welder B (right) weld output; Welder	Check fuse F4, and replace if open (see Section 8-10).
A (left) weld output okay;
	Unit overheated (High Temp. Shutdown light goes on); wait several minutes for thermostat(s) TP4 to
	reset (see Section 8-10).
	Have Factory Authorized Service Agent check Welder B (right) contactor circuit.
Low Welder A (left) weld output; Weld-	Check position of Process Selector switch (see Section 6-3).
er B (right) output okay.
	Increase Amperage/Voltage control setting.
	Check fuses F21, F22, and F23, and replace if open. If fuse(s) are open, have Factory Authorized
	Service Agent check main rectifier SR2.
	Have Factory Authorized Service Agent check main rectifier SR2, synchronization transformers T5,
	T6 and T7, and control board PC1.
Low Welder B (right) weld output;	Check position of Process Selector switch (see Section 6-3).
Welder A (left) weld output okay.
	Increase Amperage/Voltage control setting.
	Check fuses F11, F12, and F13, and replace if open. If fuse(s) are open, have Factory Authorized
	Service Agent check main rectifier SR3.
	Have Factory Authorized Service Agent check main rectifier SR3, synchronization transformers T8,
	T9 and T10, and control board PC5.

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