ESAB Aristotig 405 AC/DC, Service Manual

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10. Test the drive signals for the primary switch (X11.1-X11.2, X12.1-X12.2):
Voltages: +12 V / -12 V; duty cycle: 45% to 48%; frequency 66 kHz
Cf. "TESTING OF MODULES A4, A5, A11, A12" (Checking gate pulses)
11. Increase voltage on isolating transformer up to 253 V max. (conductor voltage not to exceed
440 V). Driving must remain unchanged in range from 150 V to 253 V.
12. Reduce voltage on isolating transformer and wait until A1 is OFF. Disconnect the oscillo-
scope.
13. Connect drive leads (A1: X10, X11, X12) again; then increase voltage on isolating trans-
former again.
From 150 V on the isolating transformer, the no-load voltage (86 V to 92 V) will be applied
and will be constant up to 253 V.
14. Set mode to "4-Cycle DC-TIG with HF".
Set load resistor to "Short-Circuit". Set isolating transformer to 230 V. Start the unit by
pressing the Torch button.
Increase the current starting at MIN, and check the following:
Maximum short-circuit current without short-circuit jumper: 70 A
Short-circuit current when 3 A are drawn from the isolating transformer (with short-circuit
jumper): 110 A
The short-circuit jumper disables the current-lowering function when short-circuit is
detected. This function is located on module A8 (J1). It detects short-circuit when current
flows for about 2 seconds while the output voltage is less than approx. 8 V.
Do not forget: After starting the hot test, remove the short-circuit jumper from J1.
15. Set the load resistance to 0.2
Ω
. Increase the current to isolating transformer current of 3 A;
then the load current must be about 40 A.
The previous two test steps enable faults to be detected on the isolating transformer since, if
faults have occurred, the figures given in table are not normally reached.
16. Disconnect the isolating transformer. Connect the unit to mains voltage.
Increase the current until it becomes 'wavy'; do not exceed 250 A:
17. Load resistance: 0.05
Ω
18. Check maximum display: 400.
When in the "4-Cycle DC" mode with HF, do not start the unit; only check the display range
by turning the current potentiometer.
19. Check the maximum currents and adjust by means of TR4 on module A8 as necessary:
When making adjustments, make sure you do not exceed the maximum permitted current of
the unit. To achieve this, you should have some means of measuring the current accurately
and interference-free.
20. "4-Cycle DC" mode with HF: Trim MIN DC by means of TR3 on module A8:
21. "4-Cycle AC1" mode; Test: MIN AC: 10 A.
If necessary, adjust by means of TR6 on module A8.
22. Test: Change-over current 40 A, Frequency regulation, Balance control.
A transformer shunt or current-measuring prongs and an oscilloscope are required for this
test step.