ESAB PCM-1125, Instruction Manual

Page: 37 / 72

7
b. Check T transformer secondary voltages at the plugs P1 and P. Refer to system schematic. Replace the transformer
if the correct secondary voltages are not present.
c. If everything above checks out all right, then the PCB1 Control Board should be replaced.
D. Fault light activates when torch switch is closed.
The Fault circuit is used to monitor conditions necessary for the safe operation of the PCM-115. The fault light will glow
amber under the following conditions and operations will come to a complete stop:
1. High/low line voltage. The Fault Light will rapidly blink on and off (5 times per second). This indicates that the input
voltage is outside the “+” or “-” 15% safe operating range rating.
. Flow fault - The fault light will be mostly on but will blink off for 1/10th of a second every second. This indicates that
the air flow is low.
a. Check the air pressure at the machine regulator. It should be adjusted to 65 psig. If no air pressure, check the air at
the supply point. Also, check for any obstructions in the air hose.
b. Air flow may be blocked at the torch tip. Check the torch consumables. Also check for any obstructions in the torch
leads.
NOTE: If above items check OK , the problem is internal. send unit to an Authorized Repair Station for repair.
c.. Put the ‘Air Check’ switch to On position. Air should flow through torch. If not, then the flow switch may be stuck
due to oil in the air. Clean air flow switch per supplier’s instructions or replace switch. To check if the flow switch is
open, put voltmeter leads between P1-1 and P1-1. It should read about 1 VDC. When the flow switch closes, the
voltage will drop to zero volts.
d. Air Check switch may also be malfunctioning if the air is flowing continuously or putting in the On position does
not turn air on.
. Over Temperature. The fault light will be mostly off but will blink on for 1/10 of a second, every second. This generally
indicates that the air flow has been blocked. Clear blockage and allow the power source to cool before operating.
a. Thermal switch may be open. It will open if the heat sink temperature reaches 80°C. With the machine power off,
check the continuity between P1-1 and P1- of the control board. If the switch is OK, then the ohmmeter should
read a direct short. If not then it should read open.
b. If the switch is malfunctioning, replace it. Clean the surface of the heat sink before installing the switch.
4. Over Current. The fault light will be on continuously. This indicates that the input current to the main transformer has
exceeded preset limits.
a. To check if the output is shorted, measure the resistance by putting the ohmmeter leads (make sure to disconnect
HI Frequency leads):”+” of the meter to Torch “+” output terminal and Work “-” lead of the meter to the “-” output
terminal. Reading should be about K Ohms. Reverse the voltmeter leads, the resistance reading should be less
than 1.5 K Ohms.
b. If the resistance reading is different than above, check the torch, the output bridge and Filter Board (PCB-5).
e. Air is On but nothing happens when torch switch is operated.
1. Check the pilot arc fuse located on the rear panel. If it is open, nothing will happen when the torch switch is de-
pressed.
. Check the torch. Make sure the heat shield is very tight.
SeCTION 5 MAINTeNANCe