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SECTION 4
b.If the motor inches, but does not run when the torch
switch is operated (energized), check the torch
switch circuit components—switch, plug, recep-
tacle, etc. If motor still does not run, check if power
source is providing open-circuit voltage to the
Digimig — if o.c.v. is not being supplied, motor will
not run. Check the power source for trouble.
c. Also check that +/- 12 volts d.c. are provided
from the power source on T1-7 and T1-5
respectively.
d.If power source is O.K., replace the I/0 and MPU
boards respectively.
E. Motor runs, but not at right speed.
1. Check tachometer assembly mounted on the end
of EH-10A wire feed motor.
2. Make sure the tach disc is securely fastened to the
motorshaft and that the strobe markings are not
scratched. Check that the disc is properly centered
in the strobe pickup on the p.c. board.
3. If all items in step 2 are in order, and motor speed
is still incorrect, replace MPU board.
F. Arc VOLTS display reads zero after TS Is oper-
ated.
1. Check that the 5-pin plug is securely connected to the
P3 receptacle on the MPU board
2. If no reading is displayed, check for arc voltage
feedback between terminals TP1 and TP2 test points
on the I/0 board (see Fig. 4-1). This voltage signal
should correspond to that shown on the power source
voltmeter.
3. If voltage still reads zero, trace the voltage pickup
wiring from the power source to digimig.
4. Remove the J-Gov. p.c. board to gain access to the
P3 plug (harness) on the MPU p.c. board. Disconnect
the P3 plug from its MPU board socket and, using a
meter check for +/-12 volt power supply output be-
tween plug pins P3-1 and P3-2 (for +12 v.) and
between plug pins P3-4 and P3-2 (for -12 v.) respec-
tively. If voltage is present, replace the MPU board.
G. Control Shut Down — either preset VOLTS or IPM
displays will flash. The control will flash the param-
eter, VOLTS or IPM, that cannot be maintained.
If this condition occurs, the respective speed and
voltage conditions (servos) need to be checked for
each of the four (4) possible schedules and, if neces-
sary, readjusted as follows:
1. This symptom can of occur as a result of either or all
of the following; the factory-set Speed and Voltage
(servo) adjustments are incorrect and the conditions
TROUBLESHOOTING
Fig. 4-1 - Input/Output (110) P.C. Board
"set" may not be
maintainable. To check and, if
necessary, readjust the servos — proceed as fol-
lows:
NOTE: Prior to checking the servos, make sure the
Digimig is connected to suitable ESAB power
source in order to obtain the necessary o.c.v.
(open circuit voltage); otherwise, the motor will
not run.
2. The factory-set Speed and Voltage (servos) adjust-
ments in this control are simultaneously checked and
displayed by actuating and holding the front-panel
Purge (Reset) key position during an actual weld
with the wirefeed motor running. The speed servo
number is displayed in left (IPM) window and should
be about 110, and the right (VOLTS) window will
display the voltage servo number. This number will
be between 90 and 100* for the actual welding
condition.
* Voltage servo setting below 95 will normally pro-
vide hot arc starts; whereas, setting over 100 will
not.
3. If a Speed abort had occurred (IPM window flashing),
check and/or adjust the speed (servo) as follows:
Open the pressure roll clapper (so as not to feed
wire), actuate the Purge (Reset) switch position and
close the torch switch lever. Check the number in the
IPM window — it may appear unsteady but readable
and should be about 110.
If it is higher or lower, use the Inc/Dec toggle (below
the IPM window) to adjust the number to 110 - while
"holding" the Purge (Reset) toggle as mentioned
above and while the wire feed motor is running.
TP2
TP1
19
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