Troubleshooting guide

SECTION 4

TROUBLESHOOTING

2. Faulty SCRs or diodes in Boost Bridge assembly. Check per Section 3, paragraph 3.4, steps A and C.

3. SCR logic board defective. Replace board.

D. No Current Control or Erratic Output Current (O.C.V. is okay).

1. No current control -- none at all, fixed, or all out.

a. Missing power or blown fuse links in Main or Boost Bridges.

b. Defective SCR board.

c. Defective constant current (CC) board.

d. If current remains fixed at around 500 amperes (in Panel position), the bottom of the current control

potentiometer (R28) may not be connected. This results in applying +10 volts straight into CC board.

e. Missing V ref signal from remote source. Check voltage from pins P1-2 to P1-1 on CC board for V

ref signal.

2. Erratic current control.

a. Defective current control potentiometer (R28) (panel and/or remote location).

b. Defective remote control switch (SW1). Check continuity.

E. Limited Output Current.

1. Single phasing resulting from blown fused link(s) F3 and/or F4, and/or defective SCR(s) or diodes in Main

Bridge. Check per Section 3, paragraph 3.4 steps A, B, or D.

2. Defective SCR board, that is not gating one of the Main Bridge SCRs.

3. Insufficient V ref signal (less than 2.000 V).

F. Short (Torch) Tip Life -- Double Arcing.

1. Low open circuit voltage. Refer to symptom C.

2. Defective SCR board.

3. Defective CC board.

4. Defective SCR in Main Bridge.

5. Pilot Arc Work connection not properly made. Refer to ESP manual.