Troubleshooting Guide - ESAB ESP-150 Manuel D'instruction

SECTION 5
NOTE: Before checking voltages in the circuit, disconnect the power from the
high frequency generator to avoid damaging your voltmeter.
Be sure unit is set up properly for voltage being used and that the gas
supplies are adequate.
A. TROUBLESHOOTING GUIDE
1. Unit Inoperative; fan does not run.
a. Check primary disconnect switch to make sure input power is being
supplied.
b. Check links on the input terminal board TB to make sure all are con-
nected to the proper input voltage being used. (See Form 14-376.)
c. Check for defective power switch (ROS).
2. No gas flow when torch switch is closed.
a. Unplug torch switch plug and check for proper operation with an ohmme-
ter connected to pins 1 and 2 of torch switch plug.
b. Defective interlock switch (ISW).
c. Check for defective solenoid valves.
d. Plug (P1) may be loose at control board (674935).
e. Defective logic board (675369).
3. No pilot arc-high frequency sparks noted at spark gap but not at the
torch.
a. Check spark gap and readjust electrodes if necessary. Replace spark
gap electrodes if worn beyond serviceability.
b. Check with an ohmmeter for continuity between torch nozzle and POS
output where torch attaches to console.
4. No pilot arc-high frequency sparks noted at spark gap and at torch
during preflow, but main contactor does not activate or chatters at
end of 2 second preflow time.
a. Check start gas pressure. It must be at least 30 psig.
b. Check cooling gas pressure (PT-26). It must be at least 50 psig.
c. If using PT-26 torch, check jumper plug between J1-5 and J1-4 on the
torch switchplug.
d. Thermal switch in bridge, inductor, or main transformer may be open.
Allow unit to cool down.
e. Defective logic board (675369).
5. No pilot arc - No spark noted in the spark gap.
a. Check to see that pilot arc contactor (PAC) closes. If it does not, and
gas flows when torch switch is closed, replace logic board (675369).
b. If PAC closes, check for proper spark gap setting (0.025-in.).
c. Check the 120V input to the high voltage transformer (HFTR).
d. Check for arcing or carbon tracking around the spark gap.
e. If all of the above check good, HFTR is most likely defective.
6. Erratic pilot arc - pilot arc contactor (PAC) chatters.
a. Defective logic board (675369).
b. Power supply may be single phasing. Check main disconnect switch
and fuses.
7. No pilot arc -pilot arc contactor (PAC) drops out when main contactor
(MC) activates at end of 2-second preflow.
a. Check for low open circuit voltage. It should be around 370 V at nominal
line voltage.
b. Check voltage between each side of resistor R29 and the WORK output
connection when MC is activated. Place negative meter lead on side of
resistor being checked and positive meter lead on the WORK output
connection. The voltage on one side should be the open circuit voltage
(370 V). The voltage on other side should be above 175 V. If lower voltage
is under 175 V, PAC will drop out.
c. Check the resistance of R29. It should be 133 K ohm.
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MAINTENANCE