9-2. Diagnostics

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1Wrapper

2Motor Control Board PC1

3LED3

4DIP Switch S1

.There is a two-position DIP

switch S1 located on motor control board PC1. These switches are factory-set in the off position and must remain in that position for the unit to op- erate correctly.

The following error messages are shown on the upper and lower displays to indicate specific errors. Explanations are in the text below:

Front panel is shown removed for purpose of

illustration only. In actual use, front panelRef. 802 687 would be in place.

ERR

COM1

Indicates a communication error.

ERR

TRG1

Indicates a trigger error.

ERR

TCH1

Indicates a tachometer error.

ERR

MTR1

Indicates a motor error.

ERR

OPT1

No gas flow detected.

ERR

OPT2

Optional error condition.

LED3-Related Error Indications

Error conditions are indicated by LED3 on PC1. To view LED3, turn Off unit, remove wrapper, and turn unit On. LED3 is most easily observed from the left side of the unit.

The LED blinks in a 2.5 second cycle. The number of blinks in this period indicates the type of error.

The priority of the errors is related to the num- ber of blinks indicating the error. The more blinks, the more severe the error (motor error is top priority). A higher priority error overrides a lower one (if a motor error and a communica- tion error existed, the light would blink four times for the motor error).

Since blink On time and blink Off time are equal in a four-blink cycle, the four−blink se- quence appears as a constant blink.

1 blink = Communication Error

2 blinks = Trigger Error

3 blinks = Tach Error

4 blinks = Motor Error

ERR COM1

The communication error occurs 2.5 sec- onds after a loss of communication between the motor and front panel boards. The user may continue to weld with this error. The er- ror may be cleared by resetting the unit (see Section 6-10).

ERR TRG1

The trigger error occurs if the user has the trigger held for more than two minutes with- out striking an arc, or if the user holds the trigger past the postflow phase in a timed weld. This error also occurs if the trigger is held when the feeder is powered up. The er- ror may be cleared by releasing the trigger.

ERR TCH1

The tach error occurs 2 seconds after the loss of tachometer feedback. The user may continue to weld with this error. The motor

speed is regulated through the monitoring of voltage and current.

ERR MTR1

The motor error indicates that the motor has been drawing too much current for too long. To remedy this, reduce the wire feed speed or the wire feeder torque load/duty cycle.

ERR OPT1

The optional 1 error indicates no coolant flow in water flow switch option. The error may be reset by reestablishing coolant flow to the gun, and then pressing any button on front panel.

ERR OPT2

The optional 2 error indicates a problem with optional device connected to RC24 on Interface Board (PC20). The error may be reset by correcting the problem, and then pressing any button on front panel.

OM-1500-9 Page 27

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Miller Electric S-74DX manual Diagnostics, LED3-Related Error Indications