CEBORA S.p.A.
23
SCR3 FIRING PULSES TEST.
Correct?
Shut-off board (48), connector J3, terminals 1 and 2 (gnd) = fig. 5.2.6, pulses for SCR3 in the
AC operation and power source loaded in table conditions.
YES
NO
♦
Check the wiring between J3 shut-off board (48) and J7 control board (40).
♦
Replace shut-off (48) and control (40) boards.
POWER SOURCE LOADED OUTPUT CURRENT TEST.
Correct?
Control board (40), connector J4, terminals 4(+) - 2(-) = -3.2 Vdc, fig. 5.2.4a, in DC and 3.2
Vac, fig. 5.2.4b in AC, with start button pressed and power source loaded in table conditions.
NO
YES
♦
Replace control board (40).
♦
Check the wiring between current transducer (5) and J4 control board (40).
♦
Make sure the current transducer (5) is properly mounted on the connector cables between
AC/DC selector switch (30) and +(AC) of the power source output terminal.
♦
With the power source off, temporarily disconnect J4 from control board (40) and check the
resistance on terminals 4 and 2 of J4 on control board (40) = approximately 9 Kohm. If
incorrect replace control board (40).
♦
Check the integrity of the power transformer (46) and inductor (50). If they show any signs of
damage or burns, replace.
♦
Check connections between secondary windings of the power transformer (46), thyristor
group (47), inductor (50), AC/DC selector switch (30), HF transformer (28) and output
terminals (-)(AB) and (+)(AC) of the power source. If you find loose connections, tighten
them and replace any components with damaged terminals.
♦
Check operation of the AC/DC selector switch (30), making sure the closing sequence of the
contacts matches the table in the electrical diagram in par. 5.1.
♦
With the power source off, temporarily disconnect the thyristor group (47) and check the
integrity of the thyristor group (47) measuring the resistance between terminals (A), (-) and
(+) of the thyristor group (47). Correct values = >Mohm for each measurement point, also
reversing the test probes. If incorrect replace the defective thyristor or the entire thyristor
group (47).
♦
With AC/DC selector switch (30) in “0” position, with power source off, make sure the diode
module (19) is intact measuring the resistance at the following points (see drawing par. 5.11):
−
A1-K2(+) - K1(-) = approximately 0.5 Vdc; A1-K2(-) - K1(+) = >Mohm;
−
A2(+) - A1-K2(-) = approximately 0.5 Vdc; A2(-) - A1-K2(+) = >Mohm;
−
A3(+) - K3(-)
= approximately 0.5 Vdc; A3(-) - K3(+)
= >Mohm.
If incorrect replace the defective diodes or the entire diode module (19).
♦
With AC/DC selector switch (30) in “0” position, check on terminals of the secondary power
circuit of the transformer (46) that voltage = approximately 60 Vac, with rated mains voltage.
If incorrect, check the connections of the primary and secondary power circuit windings of the
transformer (46), considering that each one is made up of two semi-windings arranged on the
two columns of the magnetic core. Perform the tests in par. 3.3.1. if necessary.
♦
Replace control board (40).
3.302.221
15/01/07
Summary of Contents for TIG 250 AC-DC
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