Firepower FP-18, Service Manual

Service Manual 0-2692

9

Firepower FP-18 Plasma Cutter

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.  Compressor Related

If the unit is cold, the Air Compressor may not start up or
may run sluggishly.  Most likely, when the torch switch is
depressed, the unit will click once and nothing more will
happen.  Let the unit warm up to room temperature ap-
proximately 50° F (10° C) and try again.

If the air filter on the compressor becomes clogged, the
compressor may sound more labored, cut speed and qual-
ity will be reduced, and the arc may have a more green
color.  The air filter element can be cleaned - remove it,
blow air through it, then reinstall it.

B.  Power Source Related

This system draws about 20 amps rms from the 120 VAC
service under normal operating conditions.  If the 120V
service available is saggy, pilot and cut performance 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 20 amps.
• Use as short an extension cord as possible.
• Use heavy gauge extension cords (Refer to Operat-

ing Manual 0-2691 for sizes).

• Try different outlets on different branch circuits. Use

the one that gives the strongest pilot.

C.  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.

D.  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")
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 FP-18 will cut using standoff, 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:

 X.  Symptom (Bold Type)

1.  Cause (Italic Type)

           a.  Check/Remedy (Test Type)