Lincoln Electric SVM154-A Service Manual page 73

F-28
J2
#505
TEST PROCEDURE
1. Remove input power to the LN-10 unit.
2. Using the 5/16 in. nut driver, remove
the two screws from the top of the con-
trol panel.
3. Carefully lower the control panel.
4. Locate plug J2 on the control board.
See Figure F.4. Do not remove the plug
from the control board.
5. Apply the correct input power (42 VAC)
to the LN-10 unit.
6. Carefully check for the presence of 5
VDC from 5J2 (lead #505) to 4J2 (lead
#500). This is the supply voltage from
the control board to both encoder
boards. (Volts and WFS). If this voltage
is missing or low the control board may
be defective. Also make certain the 5
VDC supply is being applied to the
encoder boards via leads #505 and
#500. See the Wiring Diagram.
TROUBLESHOOTING AND REPAIR
ENCODER PC BOARD TEST (continued)
FIGURE F.4 — ENCODER PC BOARD TEST.
#500
#526
#527
#517
#516
ENCODER
PC BOARDS
7. While slowly rotating the Volts control
check for a "pulsing" 0 to 5 VDC signal
from 8J2 (lead #516) to 6J2 (lead
#517). If the 5 VDC supply IS present
at the encoder board and the pulsing
signal is NOT, the Volts encoder board
may be faulty. Also check the lead and
plug connections between the encoder
board and the control board. See the
Wiring Diagram.
8. While slowly rotating the WFS control
check for a "pulsing" 0 to 5 VDC signal
from 3J2 (lead #526) to 7J2 (lead
#527). If the 5 VDC supply IS present
at the encoder board and the pulsing
signal is NOT, the WFS encoder board
may be faulty. Also check the lead and
plug connections between the encoder
board and the control board. See the
Wiring Diagram.
NOTE: "Pulsing" means that as the control
is rotated the signal will fluctuate from 0 to 5
VDC.
9. Remove input power to the LN-10 unit.
10. Reassemble the control panel.
LN-10
F-28