ESAB Precision Plasmarc EPP-450 Manuel D'instructions page 45

section 6
6.3.6 torch will not fire
problem
Main Arc Transfers to the work with a
short " pop", placing only a small dimple
in the work.
Arc does not start. There is no arc at the
torch. Open circuit voltage is OK.
possible cause
Remote control removes the start
signal when the main arc transfers to
the work.
Panel/Remote switch in "Remote" with
no remote control of the current
Remote current control present but
signal missing.
Current pot set too low.
Start current pot, located behind the
cover for the control PCB is set too
low.
Open connection between the power
source positive output and the work.
Fuse F6 in the Pilot arc circuit is blown. Replace F6
Fuse F7 in the pilot arc circuit is blown. Replace F7
Pilot arc High/Low switch is in the "LOW"
position when using consumables for
100A or higher (Refer to process data
included in torch manuals)
Pilot arc contactor (K4) faulty.
Faulty PCB1
45
troubleshootinG
action
Place Panel/Remote switch in "Panel"
position
Check f or c urrent r eference s ignal a t T B1-
4(+) and TB1-5(-). See Signal vs. Output
Current Curve this section.
Increase current pot setting.
Increase the start current post setting
to "7".
Repair connection
Change Pilot arc to "High" position.
(Refer to process data included in torch
manuals)
Replace K4
Replace PCB1 P/N 0558038312