TROUBLESHOOTING & REPAIR
F-56 F-56
RANGER 305D
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STATORSHORT CIRCUIT & GROUND TEST (continued)FIGURE F.14– WELD CONTROL BOARD
AMPHENOL1
KEY
E
C
D
A
B
LKJ
MN
FGH
I
CONTACTOR
CONTROL
L4
GROUND
120 VAC FOR WIRE FEEDER
40VAC FOR WIRE FEEDER
21WORK SENSE
2TIMES THRU FERRITE
LEADS75A, 76A, & 77A
REMOTE
CONTROL
TEST PROCEDURE
1. Perform Case Cover Removal Procedure.
2. Perform Capacitor Discharge Procedure.
3. Unplug anything that may be connected to
the auxiliary receptacles or the 14 pin
amphenol.
4. Disconnect and isolate GND-E lead from the
bottom ground screw inside the left case
front. See control Inner-Connection diagram.
See Figure F.14.
5. Disconnect the #7 and #9 leads from the field
bridge rectifier. See Wiring Diagram.
6. Using an ohmmeter, check the resistance
between chassis ground and each of the fol-
lowing points; Resistance should read very
high, 500,000 (500K) ohms minimum.
1) Pin 1 at the 14 pin amphenol, and the #5
lead that had been disconnected from the
ground screw. (this checks for a connec-
tionbetween the wire feed winding and the
auxiliary winding.)
2) Pin 1 of the 14 pin amphenol and lead #7
or #9. (This checks for a connection
between the wire feed winding and the
exciter winding.)
3) Pin 1 of the 14 pin amphenol an lead W1,
W2, or W3. (This checks for a connection
between the wire feed winding and the
weld winding).
4) Lead #5 and lead #7 or #9. (This checks
for a connection between the auxiliary
winding and the weld winding). See
Wiring Diagram.
5) Lead #5 and lead W1, W2, or W3. (This
checks for a connection the auxiliary wind-
ing and the weld winding.) See Wiring
Diagram.
6) Lead #7 or #9 and lead W1, W2, or W3.
(This checks for a connection between the
exciter winding and the weld winding.)
See Wiring Diagram.
If any of the above readings is less than 500,000
(500k) ohms, check for damaged, contaminated,
orshorted wiring or components between the test
points and the stator winding. If necessary, dis-
connect and isolate the stator leads as close to
the stator winding as possible. See wiring dia-
gram. Ifthe low resistance is determined to be
between the windings within the stator,the stator
is defective and should be replaced*.
*NOTE:
Thefield bridge rectifier and field capac-
itor may appear to function normally when tested
independently. But may malfunctions when
placed under the stress of normal operation. For
this reason, It is recommended that the bridge
rectifier and capacitor be replaced with known
good components before replacing the stator
.