Thermadyne CE CutMaster 75, Service Manual

Page: 43 / 80

Manual 0-2869 5-11 SERVICE
D. Output Diode PC Board Replacement
Follow the antistatic procedures in subsection 5.02.
NOTE
Follow the electrostatic discharge instructions pro-
vided with the replacement component to prevent
damage to the component.
Thermal pads and the large flat surface on the back
of diodes and IGBTs must be kept clean. Diodes
and IGBTs must not be bent or allowed to pick up
any foreign material. A very clean installation
between the module and the heatsink or chassis is
essential for proper operation.
1. Remove cover per subsection 5.04-A.
2. Locate the Output Diode PCB(s) located within the
Output Power PC Board on the Heatsink Shroud.
3. Carefully remove all wire connections to the Out-
put Diode Board(s).
4. Remove screw(s) securing Output Diode PC
Board(s) to the Heatsink and remove board(s) from
the Power Supply.
5. Use isopropyl alcohol to clean the heatsink and
the large flat surface on the back of the replace-
ment component(s). Do not scratch or abrade the
surfaces.
6. The thermal pad(s), provided with the replacement
part, is a thin metal pad. Remove any loose pro-
tective paper coverings from the pad(s).
NOTE
Protective coverings must be removed from the
thermal pads. Installing thermal pads with pro-
tective coverings in place will cause equipment
damage or failure.
7. Apply a round thermal pad to the heatsink with a
small piece of light-duty tape. Tape must cover
no more than 1/8” (3 mm) of the edge of the ther-
mal pad. Use the screw hole in the heatsink as a
guide to position the pad.
8. Secure replacement board as follows:
a. Position the hardware at the bottom of a recess
in the face of the diode. Ensure that the washer
is under the head of the screw(s).
b. Torque hardware to 17 in-lb. (1.9 Nm).
NOTE
Failure to torque properly will cause component
damage.
9. Connect wires as follows:
From Output
Diode A
To Output
Power PCB
From Output
Diode B
To Output
Power PCB
E34, E39 E37 E34, E39 E36
E48, E50 E47 E48, E50 E45
E56, E60 E58 E56, E60 E57
E53, E54 E52 E53, E54 E49
Output Diode A Output Diode B
E. Output Power PC Board Replacement
Follow the antistatic procedures in subsection 5.02.
NOTE
Follow the electrostatic discharge instructions pro-
vided with the replacement component to prevent
damage to the component.
1. Remove cover per subsection 5.04-A.
2. Locate the Power Output PC Board, mounted to
the Heatsink Shroud.
3. Carefully remove all wire connections to the Out-
put Diodes.
4. Straighten the Output Diode wires to be perpen-
dicular to the Output Power PC Board.
5. Label, then disconnect all other wire connections
to the Output Power PC Board. Refer to Appen-
dix pages for wiring connection layout.
6. Remove the bolts at the top left and bottom right
corners of the Output Power PC Board.
A-03166
Screw Locations
7. Lift the Output Power PC Board off its supports,
and set aside.
8. Install the replacement Output Power PC Board
by reversing the above steps.