Snap-On TIG 250 AC-DC, Service Manual

Page: 11 / 37

CEBORA S.p.A.
11
CONTROL BOARD (40) POWER SUPPLY TEST.
‰
Control board (40), connector :
−
J2, terminals 1 and 2 = 16 Vac, pulse generator synchronization signal for SCR1, SCR2 and
SCR3 on control board (40).
−
J3, terminals 2 - 4 - 1 = 16 - 0 - 16 Vac, power supply to internal circuits of control board
(40).
−
J3, terminals 5 - 4 - 6 = 8 - 0 - 8 Vac, power supply to microprocessor circuits on control
board (40).
− J5, terminals 1 - 2 = 26 Vac, start command circuit power supply.
− J6, terminals 4 - 5 - 6 = 7 - 0 - 7 Vac, pulse power source supply for SCR2 and SCR3.
− J6, terminals 1 - 2 = 7 Vac, pulse power source supply for SCR1.
Correct?
− J8, terminals 1 - 2 = 30 Vac, protection circuit power supply.
YES
NO
♦
Check the wiring between J2 control board (40) and J4 fuse board (4).
♦
Check the wiring between J3 control board (40) and J1 fuse board (4).
♦
Check the wiring between J5 control board (40) and 26 Vac signal winding of the
transformer (46).
♦
Check the wiring between J6 control board (40) and J2 fuse board (4).
♦
Check the wiring between J8 control board (40) and 30 Vac signal winding of the
transformer (46).
♦
With power source off, temporarily disconnect connectors J2, J3, J5, J6 and J8, on
control board (40) and check the resistance on the following points of control
board (40):
− Conn. J2, terminals 1 - 2 = approximately 900 ohm;
−
Conn. J3, terminals 4 - 1 = 4 - 2 = >Mohm;
− Conn. J3, terminals 4 - 5 = 4 - 6 = >Mohm;
−
Conn. J5, terminals 1 - 2 = >Mohm;
− Conn. J6, terminals 5 - 4 = 5 - 6 = >Mohm;
−
Conn. J6, terminals 1 - 2 = >Mohm;
− Conn. J8, terminals 1 - 2 = >Mohm.
If incorrect replace control board (40).
♦
With power source off, temporarily disconnect connectors J2, J3, J5, J6 and J8, on
control board (40). Power up again and check once more for the presence of
voltage on the connectors of control board (40):
−
Conn. J2, terminals 1 - 2 = 16 Vac (fuse F4 on fuse board (4);
− Conn. J3, terminals 4 - 1 = 4 - 2 = 16 Vac (fuse F1 on fuse board (4);
−
Conn. J3, terminals 4 - 5 = 4 - 6 = 8 Vac (fuse F1 on fuse board (4);
− Conn. J5, terminals 1 - 2 = 22 Vac;
− Conn. J6, terminals 5 - 4 = 5 - 6 = 7 Vac (fuse F3 on fuse board (4);
− Conn. J6, terminals 1 - 2 = 7 Vac (fuse F2 on fuse board (4);
− Conn. J8, terminals 1 - 2 = 30 Vac.
If incorrect, make sure the fuses F1, F2, F3 on fuse board (4) are intact, or replace
fuse board (4) or service transformer (4) or power transformer (46).
♦
Replace control board (40).
3.302.221 15/01/07