Thermadyne CE CutMaster 75, Service Manual

Page: 38 / 80

SERVICE 5-6 Manual 0-2869
b. Secure the diode and rectangular pad to the
chassis with the replacement screws and wash-
ers. Ensure that the rectangular pad is aligned
with the rectangular flat surface on the back of
the diode.
For IGBTs:
a. Apply a round thermal pad to the heatsink with
a small piece of light-duty tape. The tape must
cover no more than 1/8" (3mm) of the edge of
the thermal pad. Use the screw hole in the heat-
sink as a guide to position the pard.
b. Remove the small jumpers from the component
being replaced and transfer them to the replace-
ment component.
c. Secure replacement board(s) with the screw re-
moved previously. Ensure that the washer is
under the head of the screw.
10. Torque screw to 17 in-lb. (1.9 Nm).
NOTE
Failure to torque properly will cause component
damage.
11. Connect wires per the following applicable
chart(s).
Input Diode To Main PCB Input Diode To Main PCB
E18 E2 E18 E3
E13 E2 E13 E2
E5 E1 E5 E1
E14, E16 E15 E14, E16 E15
E6, E8 E7 E6, E8 E7
400V, 460V, 600V
Power Supplies
208/230V Power Supplies
CutMaster 75 Input Diode Connections
IGBT A
Connector
To Main PCB
Connector
IGBT B
Connector
To Main PCB
Connector
J3 J25 J3 J31
J7 J30 J7 J26
E9, E11 E10 E9, E11 E27
E19, E21 E20 E19, E21 E30
E12, E17 E4 E12, E17 E23
IGBT A IGBT B
CutMaster 75 IGBT Connections
13. Stand the unit upright; re-install the cover.
E. Main Power PC Board Replacement
Follow the antistatic procedures in subsection 5.02.
1. Remove cover per subsection 5.04-A.
2. Remove the Logic PC Board per subsection 5.06-C.
3. Label and disconnect all wire and cable connec-
tions to the Main PC Board. Refer to the Main PC
Board Wiring Diagrams in the Appendix Pages if
necessary. Straighten the connections to the
smaller PC Boards to be perpendicular to the Main
PC Board.
4. Remove the two long Transformer screws secur-
ing the Transformer to the Center Chassis.
5. Remove the other screws securing the PC Board
to the Center Chassis.
A-03165
Screw locations
6. Remove the Logic Board standoffs.
7. Carefully remove the original PC Board from the
unit.
8. Install the replacement PC Board by reversing the
steps above. It may be easier to install the PC Board
if the Power Supply is turned on its right side first.
Refer to the charts in subsection 5.06-D for input
diode and IGBT wiring connection points.