Lincoln Electric IDEALARC DC-655 Service Manual page 103

G-3
Control Board Schematic (G3384)
315
SHORTED SCR
A.C. PROTECTION
317
TO (+)
OUTPUT STUD
CC
VFB
BUFFER
CV
VFB
BUFFER
TO OPTIONAL
DIGITAL METER PCB
201
REF
COM
201
CURRENT
AMPLIFIER
202
202
TO OPTIONAL
DIGITAL METER PCB
-10V
CONTROL POT
REFERENCE
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not avail-
able from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in
danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
ELECTRICAL DIAGRAMS
IDLE SHUTDOWN
TIMER
TIMER
CHIP
TIMER INPUT
TRIGGER
OPEN
ENABLE
Vco
HOT START
ARC FORCE
CC CONTROL
REFERENCE
>15 AMP
CURRENT
SWITCH
CURRENT FEED BACK
CVI
START
CV CURRENT LIMITING
REFERENCE
Ico
REFERENCE
SIGNAL
BUFFER
TIMER OUTPUT
MODE
SWITCHING
CURRENT SWITCH
0.5 SEC TIMER
CV SUBARC FEEDBACK
CV FEEDBACK
POT FAULT
PROTECTION
POWER SUPPLY
317
TO
THERMAL FAN/
SNUBBER PCB
CONTROL
AMPLIFIER
GAIN=27
SLOPE
BUFFER
INTERCEPT
BUFFER
HOLD
LOW
SHUT-
DOWN
OVER
CURRENT
PROTECTION
PEAK
CURRENT
PROTECTION
IDLE ZERO
REFERENCE
TO
FIRING PCB
G-3
315
TO
THERMAL FAN/
SNUBBER PCB
318
FIRING
INTERFACE
A
G3384
G3384
A
DC 655