Tweco PCM-120 Machine Torch - Manual (Page 38)

CUSTOMER/OPERATOR SERVICE 5-8 Manual 0-2698
B. Reassembling Machine Torch Assembly
NOTE
Verify that the small rubber duck valve is in torch
plasma fitting.
1. Remove the rigid insulator from the old Torch
Head Assembly from between the layers of
estermat paper.
2. Slide the rigid insulator between the layers of
estermat paper on the replacement Torch Head
Assembly (see note).
NOTE
Over a period of time there may be a breakdown of
the estermat paper causing the Torch Head to short
out if the rigid insulator is not installed.
Two Layers Of
Estermat Paper
Rigid Torch
Leads Insulator A-01577
Figure 5-9 Rigid Insulator Installation
3. Secure the rigid insulator in place with electrical
tape.
4. Slide replacement shrink on tubing on leads.
5. Connect the plasma (+), secondary, coolant sup-
ply, (-) and coolant return connectors.
6. Secure leads and tubing with single layer of elec-
trical tape.
7. Slide the torch adapter down over the leads and
screw the adaptor securely onto the back of the
torch head assembly.
8. Slide the positioning tube down over the leads
and thread it into the torch adaptor on the torch
head assembly.
9. Apply tape to the torch leads sleeving at the back
end of the positioning tube.
10. Position shrink on tubing over the tape and shrink.
11. Install the front end torch parts.
5.08 Torch And Leads
Troubleshooting
A. General Information
Failures in the Torch and Leads can be isolated to the Torch
Head or Torch Lead components. To properly isolate the
failed part requires the use of an ohmmeter and a Hi-Pot
Tester.
WARNING
The use of a Hi-Pot Tester should be performed only
by a qualified electronic technician.
In the Torch Head the center insulator separates the nega-
tive and positive charged sections of the torch. If the cen-
ter insulator does not provide adequate resistance, cur-
rent which is intended for the pilot arc may be dissipated
into the torch head, resulting in torch failure.
In the Torch Leads the negative and positive leads are
isolated from each other. If there is not adequate resis-
tance between the leads then torch failure may occur.
B. Quick Check Procedure
This quick check will identify major isolation failures in
the Torch Head or Torch Lead components using an ohm-
meter.
The actual assembly and consumables may vary for dif-
ferent torches but the basic procedure is the same for all
torches. Make the quick check on the Torch Head and
Leads per the following procedure:
WARNINGS
Disconnect primary power to the system before
disassembling the torch or torch leads.
DO NOT touch any internal torch parts while the
AC indicator light of the Power Supply is ON.
1. Remove the consumables from the torch.
2. Disconnect the torch leads from the power sup-
ply to isolate the torch from power supply circuits.