Drive Unit Assembly; Troubleshooting - Miller Electric cyclomatic DWF3 Owner's Manual

SECTION 4
4.4

DRIVE UNIT ASSEMBLY

Figure 4.2 shows an exploded view of the drive unit; user replaceable parts are listed in Table 4.2.
4.5

TROUBLESHOOTING

LINE VOLTAGE IS EXPOSED INSIDE THE CONTROL UNIT. TAKE PRECAUTION TO AVOID ELECTRIC
SHOCK WHEN COVER IS REMOVED.
The TROUBLESHOOTING section of this manual is not intended to be a step–by–step guide to problem
solving of all possible failure modes. It is intended to point the way to areas which are most likely to cause
difficulties. All repairs should be referred to a qualified technician.
Refer to Figure 5.1 (DWF–3 schematic) and also Figure 4.1 to aid in locating components and test points.
The CIRCUIT DESCRIPTION section (5.1 – 5.4) of this manual should prove helpful in isolating problems.
Some possible trouble areas may be verified by following the repair steps indicated below and on the following
pages.
TROUBLE INDICATION
Power ON lamp does not light. Verify that power cord is plugged in and circuit breaker is reset.
Digital display does not light.
Incorrect START/STOP de-
lays.
Feed cycle does not start.
Incorrect wire feed speed.
OM-179 078
WARNING
Verify that all plugs are installed in the circuit board.
Check +20 V (TP 9 on Controller/Driver circuit board). Replace board if
necessary.
Check lamp; replace if necessary.
Verify that power cord is plugged in and circuit breaker is reset.
Verify that all plugs are installed in the circuit board.
Check +20 V (TP 9 on Controller/Driver circuit board). Replace board if
necessary.
Check +5 V (TP 12 on Controller/Driver circuit board). Replace board if
necessary.
Replace digital display board.
Verify that all plugs are installed in the circuit board.
Recalibrate (see Section 4.3).
Replace thumbwheel assembly or circuit board.
Verify that MANUAL START/OFF/REMOTE switch is in correct posi-
tion.
Verify that all plugs are installed in the circuit board.
Replace circuit board.
Verify that SPEED CONTROL switch is in correct position.
Verify that all plugs are installed in the circuit board.
Recalibrate (see Section 4.3).
MAINTENANCE AND REPAIR
REPAIR STEPS
4-3