Troubleshooting Procedures; Troubleshooting Guide - Lincoln Electric PRO-CUT 40 Operator's Manual

TROUBLESHOOTING PROCEDURES

WARNING
ELECTRIC SHOCK CAN KILL.
BEFORE PERFORMING ANY MAINTE-
NANCE THAT REQUIRES OPENING
THE CASE OF THE POWER SOURCE:
• Disconnect input power to this machine at the
Disconnect switch and discharge input capacitors
before working inside machine.
• Do not touch electrically live parts or internal wiring.
• S1 power switch, D9 input rectifier, C1 and C2
capacitors, Switch PC boards, R1, R2, R3, R4, and
R5 resistors and T2 main transformer are all
connected to the main lines. Use care when
making voltage measurements.
• Do not troubleshoot the machine with an
oscilloscope. Do not use electrical test equipment
which has one test probe in common with the
equipment case or grounding pin of the 115 VAC
power plug. Use a battery power VOM for all
troubleshooting.
• Only qualified personnel should service this
machine.
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HOW TO USE THIS GUIDE: Carefully read through
each applicable section listed below. Remember that
most problems are caused by improper setup, such as
switch settings, control settings, etc.
If you believe the set up is correct and the trouble still
exists, first check for the obvious: input power, blown
fuses, loose PC board connectors, broken wires and
the like. The sections listed below are intended to
help you find the less obvious sources of trouble.

TROUBLESHOOTING GUIDE

ELECTRICAL SHOCK CAN KILL.
Turn off machine at the disconnect switch at the back
of the machine before tightening, cleaning or replacing
consumables.
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Visual Inspection
Clean interior of machine with a low pressure
airstream. Make a thorough inspection of all compo-
nents. Look for signs of overheating, broken leads or
other obvious problems. Many problems can be
uncovered with a good visual inspection.
Test Conditions
Perform all tests at rated input voltage. Make ohmme-
ter checks only after power has been disconnected
from machine and after capacitors have been dis-
charged.
Certain high voltage connections have been insulated
with RTV sealant. It is necessary to break through the
sealant with a sharp probe in order to make voltage or
resistance checks.
– 14 –
WARNING