7-2. Diagnostics

1 Wrapper

2 Motor Control Board PC1

3 LED3

4 P2

3

2

 

1

4

Front panel is shown removed for purpose of illustration only. In actual use, front panel would be in place.

Display On

LED3 Sequence On

 

Meter

 

Motor Control Board PC1

Indicated Error

(If Equipped)

 

 

 

 

 

 

 

HELP 11

1

Blink

Communication Error

HELP 12

2

Blinks

Trigger Error

HELP 13

3

Blinks

Tach Error

HELP 14

*4 Blinks

Motor Error

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

Ref. 802 687

Error Indications

Error conditions are indicated by LED3 on PC1 or on display (on models with meters). 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).

The communication error occurs 2.5 sec- onds after a loss of communication between the motor and the meter board (if equipped). The user may continue to weld with this er- ror. The error may be cleared by turning power Off, waiting a minimum of two sec- onds, and turning power On.

The trigger error occurs if the user has the trigger held for more than two minutes with- out striking an arc (providing current over- ride is not enabled), 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.

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.

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.

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Miller Electric S-74S, S-74D manual Diagnostics, Indicated Error, Error Indications