Tweco Pak 200 - Manual (Page 88)

TORCH MAINTENANCE 7-8 Manual 0-5057
PAK 200 TORCH MAINTENANCE
7.08 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 qualifi ed electronic technician.
In the Torch Head the center insulator separates the nega-
tive and positive charged sections of the torch. If the center
insulator does not provide adequate resistance, current
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 iso-
lated from each other. If there is not adequate resistance
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 ohmmeter.
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 as follows:
WARNING
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 supply
to isolate the torch from power supply circuits.
3. Using an ohmmeter (set to 10K or higher), check
for continuity between the positive and negative
torch fi ttings.
• If there is continuity between the two torch
fi ttings proceed to Step 4.
• If no continuity (infi nite resistance) is found
between the two torch fi ttings proceed to "C.
Checking Proper Insulation Resistance Proce-
dure".
4. Remove the Torch Head from the leads (refer to
Section "7.06 Servicing Hand Torch Compo-
nents" on page 7-5).
5. With the Torch Head disconnected from the leads,
measure the resistance between negative fi tting or
cathode body of the Torch Head and the positive
fi tting or anode body of the Torch Head.
No continuity (infi nite resistance) should be mea-
sured between negative and positive sections of
the Torch Head.
• If there is continuity, Torch Head must be re-
placed.
• If no continuity (infi nite resistance) is found
proceed to Step 6.
6. Check the torch leads by measuring the resistance
between the positive pilot lead connector and the
negative lead fi tting.
• If there is continuity, torch leads must be re-
placed.
• If no continuity (infi nite resistance) is found
proceed to paragraph ‘C’ (see NOTE).
NOTE
It is possible that the Torch Head and Torch
Leads will test properly with an ohmmeter. The
Torch Head and Torch Leads should be tested
further for insulation breakdown if no other
fault can be found.