In Tig, Gas Flows From The Torch, The Arc Does Not Start, High Frequency Missing - Cebora Power Tig 1540 DC-HF Service Manual

CEBORA S.p.A.

3.3.6 - In TIG, gas flows from the torch, the arc does not start, high frequency missing.

DURING THE FOLLOWING TESTS LEAVE FREE FROM CONNECTIONS AND DO NOT
TOUCH THE OUTPUT TERMINAL NEGATIVE (P) OF THE POWER SOURCE. THE
EVENTUAL PRESENCE OF HIGH VOLTAGE AND HIGH FREQUENCY IS DANGEROUS
FOR OPERATOR AND CAN DAMAGE THE INSTRUMENTS OR THE POWER SOURCE.
SECONDARY RECTIFIER OUTPUT VOLTAGE TEST.
Set the TIG without high frequency operation (led E lit).
Power source positive output terminal (Q)(+), and "NEG" terminal on power board (29)(-) =
+98 Vdc approximately, with start button pressed (output voltage of the secondary rectifier
output, upstream the HF transformer (27)).
♦ Make sure start command operation (see par. 3.3.4).
♦ Check the mains voltage conditions and perform test of par. 3.3.1 if necessary.
♦ Replace power board (29).
HF OSCILLATOR TEST.
Set the TIG with high frequency operation (led C lit).
Power board (29), SC1 discharger discharges at regular intervals, with start button pressed.
♦ Make sure that there is no short-circuit between terminals HT and HT on power
board (29) or in the wiring of the HF transformer (27) primary circuit.
♦ Check the connections of the secondary circuit of HF transformer (27), "NEG"
terminal of the power board (29) and "-" output terminal of the power source. If
you find loose connections, tighten and replace any damaged components.
♦ Check connections and integrity of the three capacitors (C50, C51 and C67)
which serve to prevent the high voltage and high frequency pulses generated by
the HF transformer (27), travel along the circuits into the power board (29), where
they would cause malfunctions or errors. If necessary replace them or restore their
connections.
♦ Check cable and torch electrode holder; replace if worn or damaged.
♦ Make sure the torch fitting (Gifas) has no isolation leaks, thus is not crossed by
surface high voltage discharges. If necessary, replace with a new one.
♦ Check the distance between the tips of the discharger SC1 (correct = 0.9 mm.).
♦ Replace HF transformer (27).
♦ Replace power board (29).
♦ Make sure integrity and operation of the relè RL3 on power board (29). In TIG with HF
operation, the start signal commands closing of relè RL3, and the power transformer
secondary voltage is applied to the HF generator circuit composed by the following devices:
RS1, RS2, RS3, CS1, CS2, L3, TF4, SC1, CS3, CS4, CS5, CS6 and CS7. Check the
conditions of such devices and replace them if necessary.
3.302.212
WARNING
Correct?
YES
Correct?
NO
NO
YES
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12/01/06