Troubleshooting Procedures - Lincoln Electric IDEALARC R3R 500-I Operating Manual

TROUBLESHOOTING PROCEDURES

A. PROCEDURE FOR REPLACING PC BOARDS
When a PC board is to be replaced, the following procedure must
be followed:
1. Visually inspect PC board in question. Are any of the
components damaged? Is a conductor on the back side of
the board damaged?
a. If there is no damage to the PC board, insert a new
one and see if this remedies the problem. If the
problem is remedied replace the old PC board and
see if the problem still exists with the old PC board.
1. If the problem does not exist with the old board,
check the PC board harness plug and PC board
plug for corrosion, contamination, or oversize.
2. Check leads in the harness for loose connections.
b. If there is damage to the PC board, refer to the
Troubleshooting Guide.
B. PROCEDURE FOR CHECKING DIODES
1. Isolate the diode in question. (Electrically disconnect from
other circuits.)
2. Use an ohmmeter X10 scale. Connect the meter across the
diode and note the resistance value. Reverse the ohm-
meter leads and note the resistance value.
Shorted diode – Low resistance readings in both directions.
Open diode – High or infinite resistance in both directions.
Good diode – One reading will be high or infinite and the
other reading will be low.
C. CONNECTING THE REMOTE CONTROL TO
THE MACHINE
Extreme caution must be observed when installing or extending
the wiring of a remote control. Improper connection of this unit can
Lead to failure of the current control rheostat or the control circuit.
Only the green lead can and should be grounded to the machine
case. When extending the standard remote control make sure the
leads are the same and the splice is waterproof. Be very careful
not to ground the cable when in use and do not let these
connections touch against the case.
D. OUTPUT VOLTAGE
The open circuit voltage of the machine should be 66 to 71 volts
and should not vary when the rheostat is varied unless the
machine is welding. If any other condition exists, refer to the
Troubleshooting Guide.
IM 6000
E. FAULT PROTECTION OPERATION
The overload protection circuit, in the control board, will reduce
the welding current (heat) to some safe value if the machine is
overloaded for 2 to 3 seconds. The overload values are as
appears in the following table.
Machine Name
R3R 500-I
R3R 600-I
F. CHECKING SNUBBER CIRCUIT
In case of an SCR malfunction or failure, the snubber assembly
should be checked. Turn the machine off and disconnect one lead
of the snubber assembly. (Either 221, 222 or 223 depending on
the SCR in question. See wiring diagram.) The sides of the
machine have to be removed to do this. (See the instruction
manual parts list for the exact location.)
1. Visually inspect the snubber assembly for over-heated
components.
2. Using a VOM meter on the X10 scale, connect the positive
lead to the lead removed. Touch the negative lead to the
other lead still connected to the SCR bridge. The indicating
needle on the meter will move quickly to the right (low
resistance value) and then slowly return to the left (high
resistance value). This indicates that the capacitor in the
snubber circuit is taking a charge.
3. If the needle stays to the right, the capacitor is shorted and
the assembly is defective.
4. If the needle does not move, the capacitor is open and the
assembly is defective.
G CHECKING CURRENT CONTROL RHEOSTAT
ON MACHINE
1. Turn machine off.
2. Remove the control panel screws and open the front cover.
3. Turn the current control switch to remote.
4. Disconnect the harness plug from the control board.
5. Put current range switch to B range.
6. With an ohmmeter on X1K, connect it to lead 210 and 211
on SW #2. Rotate the current control rheostat. The
resistance reading should be from around zero to 10K
ohms. Check the resistance reading between 75 on the
Amphenol and 211 on SW #2. The reading must be 10K
ohms. No reading will indicate an open rheostat and low
reading will indicate a shorted or partially shorted rheostat;
in either case, replace.
H. TOGGLE SWITCH CHECK
1. Turn off the machine power input. SW-1 has 110 volts
across it when the input power is connected.
2. Isolate the switch to be tested by removing all connecting
leads.
3. Check to make sure the switch is making connections with
a VOM meter. The meter should read zero resistance.
4. Put the ohmmeter on X1K scale and measure the
resistance between the terminal and the case of the
machine (touch a self-tapping screw). Reading should be
infinite.
5. If either step (3) or step (4) fails, replace the switch.
Idealarc R3R 500-I & 600-I
f Load Current ±5%
50 Hz 100 A
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