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3. LED L3 indicates power is being applied to fault pro-
tection relay 2CR, when wire feeder button is pressed
or jumper is connected across 2 and 4.
4. LED L4 indicates when fault protection circuit is being
activated.
5. LED L5 indicates a control signal is being supplied to
the firing circuit. As the output control is varied, LED
L5 should change brilliancy.
Machine settings
Terminals #2 and #4 jumpered on
for P.C. board
DC-1500.
troubleshooting
DC-1500. Variable Voltage opera-
tion.
All nine light emitting diodes must be lit when the power
source is turned on and the wire feed arc start button is
pressed or a jumper is connected between 2 and 4.
1. LED L7 indicates AC power being supplied to P.C. board
from control transformer T2. If not lit, check voltage
across terminals 203 and 204 on the terminal strip lo-
cated on the left side of the bottom fan baffle. Voltage
should be approximately 115 volts. If no voltage indi-
cates a supply problem, check wiring and transformer.
If voltage is present, turn the machine off, remove the
12-pin harness plug from the P.C. board, turn the ma-
chine back on and check the voltage across pins 2 and
3 on the plug. This should be approximately 115 volts.
(INPUT CONTACTOR "ON" TERMINALS 2 AND 4 CLOSED)
CHECK CONTROL BOARD
IF OFF
CHECK LED L1
IF OFF
IF ON
CHECK AC
REPLACE
INPUT TO
"CONTROL/
"CONTROL/
FAULT
FAULT
PROTECTION"
PROTECTION"
BOARD
BOARD
POSSIBLE
DEFECTIVE T7
TRANSFORMER
Output
Control
at
LED L5
IF ON
CHECK "FIRING" BOARD
LED'S
ALL
NINE LIGHTS
SHOULD
BE ON
IF YES
IF NO
CHECK GATE
LEAD
CHECK
CONNECTIONS
LED'S
TO SCR'S
L7, L8, L9
IF ONE
OR MORE
ARE OUT
CHECK AC
INPUT TO
BOARD,
203-204, 205-206
207-208
POSSIBLE
DEFECTIVE
TRANSFORMERS
T2, T3, OR T4
If no voltage and there is voltage at terminals 203 and
204 on terminal strip TS-1 this indicates a broken lead
or loose terminal on either lead 203 or 204.If voltage is
present and LED L7 is not lit, replace P.C. board.
2. LED L8 indicates AC power being supplied to P.C. board
from control transformer T3. If not, follow the same
procedure as above in (1) for terminals 205 and 206 on
terminal strip TS-1 and pins 5 and 6 on the connector.
3. LED L9 indicates AC power being supplied to P.C. board
from control transformer T4. If not, follow the same
procedure as above in (1) for terminals 207 and 208 on
terminal strip TS-1 and pins 9 and 12 on the connector.
4. LED L1 through L6 indicate gate signals are being sup-
plied to the main power SCR's L1 through L6 respec-
tively. If light L5 on the "Control/Fault Protection"
circuit P.C. board and lights L7 through L9 on the "Fir-
ing" circuit P.C. board are lit and LED's L1 through L6
are not lit, check lead 231 between the "Firing" P.C.
board and the "Control/Fault Protection" P.C. board
that is not broken and is connected to each connector.
If the lead shows continuity and LED L1 through L6 are
not lit, replace the"Firing Circuit" P.C. board. If any
one of the LED's L1 through L6 is not lit and lights L7
through L9 are lit, replace the "Firing Circuit" P.C.
board.
If troubleshooting guide indicates a possible P.C. board
problem, the guide on page ? can be used to locate the
problem.
CHECK FOR SHORT
BETWEEN ELECTRODE AND
WORK LEADS, REMOVE
EXTERNAL LEADS FROM
THE OUTPUT TERMINALS
IF TROUBLE STILL
PERSISTS,
CHECK LED L3 ON
"CONTROL/FAULT
PROTECTION" BOARD
IF LIGHT GOES ON,THEN
QUICKLY OUT WHEN START
BUTTON IS PRESSED,
"CONTROL/FAULT
PROTECTION" BOARD IS
DEFECTIVE AND SHOULD
BE REPLACED
IF ON AND
OTHER LIGHTS
ARE OUT
REPLACE
FIRING
BOARD
-14-
CHECK PROCEDURE
CHECK MODE SWITCH FOR
PROPER POSITION FOR
PROCESS BEING USED
CHECK LED'S
L4, L5, L6
FOR EQUAL
BRILLIANCY
IF LIGHTS ARE NOT ALL
APPROXIMATELY EQUAL
BRIGHT, REPLACE
FIRING P.C. BOARD
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