Service Manual 0-2717
11
COUGAR 125 Plasma Cutter
D. Short Torch Parts Life
1. Exceeding system capability (material too thick)
2. Excessive pilot arc time
3. Improperly assembled torch
4. Incorrect gas pressure/flow
5. Ground or work lead not connected
3.4 Common Operating
Problems
Getting used to the way the system sounds and feels while
it is operating properly will help to determine the nature
of problems if they arise.
A. Power Source Related
If the available 120V service is saggy, pilot and cut per-
formance will be degraded. In some cases, the service
circuit breaker may open during use. Some things that
will help:
• Use a service fused or circuit breaker for correct
amperage (Refer to Operator Manual 0-2716, sub-
section 4.0-D for service amperage.)
• Use heavy gauge extension cords (Refer to Operat-
ing Manual 0-2716 for sizes).
• Use as short an extension cord as possible.
• Try different outlets on different branch circuits. Use
the one that gives the strongest pilot.
B. Power Supply/Torch Related
In some instances when the torch switch is pressed there
is no pilot. You may need to try several times before the
torch fires.
If the torch does not fire (no pilot arc) soon after the torch
switch is activated, try releasing the torch switch and let-
ting the leads bleed down before trying again. This should
help because the torch fires best at a lower voltage with
lower air pressure at the torch.
C. Cutting Related
1. Piloting
One of the features of this plasma cutter is the con-
stant DC pilot. This means the plasma arc is always
“on”- either as a pilot arc, or a cutting arc, resulting in
a very smooth, forgiving system. This also means that
the torch tip will wear fairly rapidly if you pilot for
an extended time or cut with too great a standoff (es-
sentially switching from a transferred cutting arc back
to the constant DC pilot arc).
The best way to prevent this is to pilot for no more
than 5 seconds at a time (or start with the torch in
contact with the material) and “drag cut”, that is, hold
the tip in direct contact with the material to be cut.
For some materials, holding a slight standoff (1/
16")(1.6 mm) may provide a better cut.
NOTE
Piloting is harder on parts life than actual cutting
because the pilot arc is directed from the electrode
to the tip rather than to a workpiece. Whenever
possible, avoid excessive pilot arc time to improve
parts life.
2. Torch Standoff
Improper standoff (the distance between the torch tip
and workpiece) can adversely affect tip life as well as
shield cup life. Reducing standoff will generally re-
sult in a more square cut.
NOTE
Although the COUGAR 125 will cut using stand-
off, this unit is primarily a drag-cutting machine.
3.5 Troubleshooting Guide
A. General
The troubleshooting covered in this Service Manual re-
quires power supply disassembly and live measurements.
Troubleshooting and repairing this unit is a process which
should be undertaken only by those familiar with high
voltage high power electronic equipment.
WARNING
There are extremely dangerous voltage and power
levels present inside this unit. Do not attempt to
diagnose or repair unless you have had training in
power electronics measurement and troubleshoot-
ing techniques.
B. How To Use This Guide
The following information is a guide to help determine
the most likely causes for various symptoms. The guide
is set up in the following manner:
