Tweco PAK 15XC - Manual (Page 91)

Manual 0-2251 87 CUSTOMER/OPERATOR SERVICE
5.11 TROUBLESHOOTING GUIDE (continued)
SYMPTOM POSSIBLE CAUSE REMEDY
L. No pilot arc. DC indicator
on, PCR not energized
M. No pilot. PILOT indicator
on, PCR energized, little
or no spark at spark gap
points
N. Weak or sputtering pilot.
HF stays on during pilot
O. No pilot. PILOT indicator
on, strong spark visible at
spark gap points
1. Faulty logic board, switch-
ing board, or shunt amp
board
1. Faulty PSR relay
2. Faulty HF transformer
(T3)
3. Faulty capacitor (C31)
1. Plasma gas pressure too
high
2. Low OCV (normal 290-
350) caused by improper
connection of voltage
selection bus bars
3. Low OCV caused by
faulty voltage selection PC
board
1. Electrode shorted against
tip
2. Shorted torch head
3. Faulty capacitor (C25)
4. Broken conductor in torch
lead
5. Shorted torch lead
6. Dirty or wet torch lead
1. See Section 5.12-Test L
1. Check for faulty NC
contacts or poor relay
connection in socket
2. Check and replace if
necessary.
3. Check capacitor and
replace if necessary
1. Adjust pressure
2. Check input voltage
connections (Section 3.4)
3. If three-phase input
voltage is within the lower
half of range (see Section
5.10, Troubleshooting
Theory, Input Voltage
Selection), D18 on voltage
selection PC board should
not be lit. If D18 is lit,
replace the voltage selec-
tion PC board.
1. Thread electrode securely
into torch head
2. Check and replace if
necessary
3. Check and replace if
necessary
4. Check and replace if
necessary
5. Check and replace if
necessary
6. Clean and dry torch lead
(continued)