Lincoln Electric SVM188-A Service Manual page 51

F-11
PC BOARD TROUBLESHOOTING GUIDE (continued)
1
2 (256)
(291) 8
J2
(290) 7
5 (231)
(255) 6
J3
1 (210)
(222)12
1
LED2
J1
CONTROL BOARD
1. With the DC-600 set for the Test Conditions, all
the LEDs except LED 4 should be lit.
2. LED 1 indicates the 120vac input to the Control
Board and should be ON whenever the Power
Switch is ON. If not check for voltage at leads 255
& 256 (J2- pin 6 & pin 3). If there is no voltage,
check the wiring from the input power circuit. See
the Wiring Diagram.
3. LED 2 indicates presence of Arc Voltage feedback
to the Control Board and should be ON. LED 2
increases in brilliance as the arc voltage increases.
If not ON check the voltage at leads 210+ (J3-pin1)
to lead 222- (J1-pin12).
4. LED 3 indicates that power is being applied to the
Fault Protection relay (CR-2) and should be ON
whenever the Power Switch is ON. Under a "fault"
condition, LED 3 will go OFF and LED 4 will turn
ON. See Protective Devices and Shutdown
Circuits.
TROUBLESHOOTING AND REPAIR
FIGURE F.2 – CONTROL BOARD LEDs
LED3
LED1
LED4
LED6
DC-600
LED5
DC600 CONTROL G3409-1
5. LED 4 indicates an overload or "fault" condition and
is normally OFF. If it comes ON, the input contactor
(CR-1) will open and the machine will shut down.
The Power Switch must be turned OFF and back
ON to reset the welder. See Protective Devices
and Shutdown Circuits.
6. LED 5 indicates a DC control signal to the Firing
Board is present at lead 231 (J2-pin5). LED 5 will
vary in brilliance as the Control Potentiometer is
changed getting dimmer as output is increased
(opposite of LED 2)
NOTE: LED 5 will be very dim or OFF in CC (Stick)
Mode until a load is applied (arc struck).
7. LED 6 indicates a signal from the Firing Board that
a 'trigger' has been applied. LED 6 should be ON
whenever there is a closure of the 2 & 4 circuit. See
Firing Board information regarding LED 10.
F-11