Lincoln Electric DC-650 PRO IM463-A - Manual (Page 25)

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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
Procedure for Troubleshooting PC Boards
Before replacing a PC board which is suspected of
being defective, visually inspect the PC board in
question for any electrical or mechanical damage to
any of its components and conductors on the back of
the board.
a. If there is no visible damage to the PC board,
install a new one and see if this remedies the
problem. If the problem is remedied, reinstall the
old PC board to see if the problem still exists. If it
does no longer exist with old PC board:
1. Check the PC board harness connector pins for
corrosion, contamination, or looseness.
2. Check leads in the plug harness for loose or
intermittent connection.
b. If PC board is visibly damaged electrically, before
possibly subjecting the new PC board to the same
cause of failure, check for possible shorts, opens,
or grounds caused by:
1. Frayed or pinched lead insulation.
2. Poor lead termination, such as a poor contact
or a short to adjacent connection or surface.
3. Shorted or open motor leads, or other external
leads.
4. Foreign matter or interference behind the PC
boards.
c. If PC board is visibly damaged mechanically,
inspect for cause, then remedy before installing a
replacement PC board.
If there is damage to the PC board or if replacing
PC board corrects problem, return it to the local
Lincoln Electric Field Service Shop.
ELECTRIC SHOCK can kill.
• Have a qualified individual install and
service this equipment.
• Turn the power source input power off
at the disconnect switch before
working on this equipment.
• Do not touch electrically hot parts.
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WARNING