Troubleshooting Guide - ESAB Heliarc 252 Instruction Manual

SECTION 5
CONDITION
1-Unit completely
Inoperative
2-No welding output.
Fan operative
3-Low or unstable
open-circuit voltage
4-Erratic output weld
current.
5-Minimum welding
output.
6-High weld output,
current control does
not vary the output.
7-Absence of High
Frequency while
selector switch (S4) is
in START mode only.
8-Insufficient or absence
of high frequency
Table 5-1. Troubleshooting Guide
A. Open line fuses - check the line fuses for continuity and replace if necessary. If the fuses continue
to open, the jumper links may not be in proper position.
See Primary Electrical Connections.
B. No power input - check position of line disconnect switch.
C. Improper jumper link placement on input terminal board. See Primary Electrical Connection.
D. Defective power on/off switch (S1)on rear panel -check continuity of S1 and
replace if necessary.
A. Power source magnetics overheating-thermal switch (TS1 or TS2) tripped due to restricted cooling
air flow,or over extended duty cycle. Allow unit to cool for at least 5minutes with fan running to let
TS reset.
B. Contactor switch (S3) in the TIG REMOTE (middle) position without a remote contactor control
connected to the Remote Control receptacle J2. Place S3 in
STICK (up) or TIG ON (down) position or make remote torch connection at J2.
C. Defective Contactor switch (S3) and/or wiring. Check continuity and replace if necessary.
D. Defective Control PC board.
E. Defective Current Selector switch (S2) and/or wiring. Check continuity of S2 and ensure that all
F. connections are secure and correct. Replace S2 if defective.
Defective Current Control potentiometer (R3).
A. Current control pot set too low for welding application. Increase setting of R3.
B. Defective SCR in main bridge. Check the resistance across the SCR on the R x 1 scale. If the
reading is high, the SCR is good. If the resistance is low or zero, the SCR is defective. To check
the gate,connect the gate lead to the anode of the SCR and read the forward resistance across the
SCR anode to cathode. If the internal voltage of the meter is high enough, the meter should read a
low resistance.
C. Defective Current Selector switch (S2) and/or wiring. See Condition 2 -E.
D. Defective Control PC board.
A. Intermittent shunt connections. Check connections to shunt.
B. Defective SCR in main bridge. See Condition 3-B.
C. Defective Control PC board. Replace PC board.
D. Excessive high frequency. Check spark gaps and adjust if necessary (see Maintenance Section).
Check all connections and components in high frequency bypass circuit and replace any defective
components.
A. Check for defective Current Control potentiometer (R3).
A. Open shunt connection. Check connections to shunt.
B. Defective Control PC board. Replace if defective.
A. Control PC board may be defective. Replace if defective.
A. High frequency switch in the OFF position. Check S4 and place in START or CONTINUOUS posi-
B. tion.
C. Improper spark gap. Clean and adjust spark gaps, if necessary. See Spark Gap Servicing.
D. Defective S4 and/or wiring. Make continuity check and replace if necessary.
Defective Control PC board.
ACTION
36
TROUBLESHOOTING