Miller Electric S-21E - Manual (Page 19)

Table 8-1. Troubleshooting
TROUBLE CAUSE REMEDY
Wire does not feed. Circuit breaker CB1. Check gun liner, hub tension, and drive roll
pressure (see Section 4). Reset CBl (see Sec
tion 10-5).
Loose or improperly made gun
trigger connection.
Check gun trigger connection (see Section
4-3).
Gun trigger. See gun Owner’s Manual.
Welding gun shorted. Repair or replace welding gun.
Motor Ml. Check connections for continuity to Ml. Check
motor brushes (see Section 10-4). Replace Ml
if necessary.
Motor Control Board PCi or
poor connections to PCl.
Check connections for continuity to PCl.
Check PCi according to Diagram 8-2 and Sec
tion 8-4. Replace PCl if necessary.
Wire feeds erratically. Pressure on drive roll is insuf-
ficient.
Rotate pressure adjustment knob counter
clockwise in 1/4 turn increments until the wire
stops slipping (see Section 4-2).
Drive roll wrong size for wire
size used.
Change to correct size drive roll (see Section
4-2).
Drive rolls worn. Replace drive rolls (see Section 4-2).
Dirt in drive rolls. Clean drive rolls (see Section l0-lC).
Motor Control Board PCl or
poor connections to PCi. Check connections for continuity to PCi.
Check PCi according to Diagram 8-2 and Sec
tion 8-4. Replace PCi if necessary.
Wire feeds but there is no gas
flow.
Gas valve GSl. Check GS1 for proper coil voltage and connec
tions (see Diagram 8-1). Check continuity of coil.
Replace GSl if necessary.
Motor Control Board PCl or
poor connections to PCl. Check connections for continuity to PCl.
Check PCl according to Diagram 8-2 and Sec
tion 8-4. Replace PCl if necessary.
Wire does not feed until trigger
is pulled but continues to feed
after trigger is released.
Welding gun is shorted be-
tween one of the trigger leads
and weld cable.
Repair or replace welding gun.
Gun nozzle opening restricted. Weld spatter or foreign matter
accumulation.
Carefully remove any weld spatter or foreign
matter which may accumulate around the
nozzle opening. Use a hardwood stick, never a
metal tool.
The gas valve in the feeder is
rattling loudly along with possi-
ble erratic or slow wire feed
speed.
Welding gun is shorted be-
tween one of the trigger leads
and weld cable.
Repair or replace welding gun.
Motor runs but wire is not ener-
gized with Spot/Burnback Op-
tion installed.
Spot/Burnback Board PC2 or
poor connections to PC2.
Check connections for continuity to PC2. Check
PC2 according to Diagram 8-3 and Section 8-5.
Replace PC2 if necessary.
TM-i 571 Page 15 5-21E