Lincoln Electric MULTI-SOURCE IM692 - Manual (Page 17)

5. LEDs 1 through 6 indicate gate signals are being
sent to the main SCRs 1 through 6 respectively. If
LED2 on the Control board is bright, along with
LEDs 7, 8, and 9 on Firing board, and LEDs 1
through 6 are unequal in brightness, check to make
sure lead 231 between Control board and Firing
board is not broken. (If lead 231 is removed while
the machine output is at open circuit, the output
voltage peaks may be unregulated and cause the
over-voltage protection circuit to open the input
contactor. The over-voltage protection circuit may
disabled by disconnecting lead 222D at the nega-
tive output stud or at pin 1 of P2. NOTE: The
machine may not be used for welding with the pro-
tection circuit disabled.
6. If one or more of LEDs 1 through 6 are off, LEDs 7,
8, and 9 are on and the voltage on lead 231 from
the Control board (pin 13, P5 to pin 12, P5) is 3 to
13Vdc replace the Firing PCB.
E-4 TROUBLESHOOTING E-4
MULTI-SOURCE
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.
CAUTION
Observe all Safety Guidelines detailed throughout this manual
PC BOARD TROUBLESHOOTING
GUIDE - FIRING P.C. BOARD
1. LEDs 1 through 9 must be lit when the Multi-Source
is turned on and the Control board is sending an
enable signal to the Firing board (pin 7 in P8 is low
in reference to common at pin 12 in P5).
2. LEDs 7, 8, and 9 indicate AC power being supplied
to the P.C. board from auxiliary windings on the
main transformer (T1). If a LED is not on, turn the
machine off and unplug P8 from the firing board.
Turn the machine back on and check the following
voltages:
3. If all voltages are present, turn power off, and plug
P5 back into J5. Turn power back on. If LEDs 7, 8
or 9 are still not lit, replace Firing PCB.
4. If voltages were not present, check the circuit back
through the external dropping resistors to the auxil-
iary windings for a possible open resistor or wire.
LED that was off
7
8
9
Check AC voltage between
P8 pins 2 & 1 (wires 283,284)
P8 pins 4 & 3 (wires 285,286)
P8 pins 6 & 5 (wires 287,288)
Voltage should be approximately
32Vac
32Vac
32Vac