Firepower, a Thermadyne Company FIREPOWER FP-82 - Manual (Page 37)

Manual 0-2871 5-5 REPAIRS & REPLACEMENT PROCEDURES
D. IGBT Circuit PC Board or Input Diode PC
Board Replacement
Follow the antistatic procedures in subsection 5.02. The
Power Supply includes two IGBT Circuit PC Boards.
NOTE
Follow the electrostatic discharge instructions pro-
vided with the replacement component to prevent
damage to the component.
Thermal pads, heatsinks, 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 instal-
lation between the module and the heatsink or chas-
sis is essential for proper operation.
1. Remove cover per subsection 5.04-A.
2. Turn the Power Supply onto its side.
3. Locate the IGBT Circuit PC Boards or Input Diode
mounted within the Main Power PC Board. Refer
to Appendix pages for location and position.
4. For IGBTs, remove the small jumpers between the
IGBT and the Main PC Board. Transfer these jump-
ers to the replacement IGBT. Label, then remove
all other wire connections to the Board(s) being
replaced. Note the routing of wires. Ensure that
the wires are put back in the same place when in-
stalling the replacement module.
5. Remove screw(s) securing PC Board(s) to the heat-
sink and remove board(s) from the Power Supply.
6. For input diodes only:
If there is a solid metal disk attached to the heat-
sink, remove it by twisting it and pulling it away
from the heatsink. Discard the disk.
7. Use isopropyl alcohol to clean and a clean rag to
clean the heatsink or chassis area behind the com-
ponent being replaced. Clean the large flat sur-
face on the back of the replacement component.
Do not scratch or abrade the surface.
8. 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.
9. Install replacement components as follows:
For input diodes: A new style input diode assem-
bly replaces the old style input diode assembly.
A-03446
Diode
Round Thermal
Pad
Washer Screw
Solid Disk
Rectangular
Thermal Pad
Old Style Assembly
New Style Assembly
Diode
Assembly
Thermal Pad
a. Apply the rectangular thermal pad to the cen-
ter chassis with a small piece of light-duty tape.
Tape must cover no more than 1/8” (3 mm) of
the edge of the thermal pad. Use the screw
holes in the chassis as a guide to position the
pad. Align the pad to match the position of
the rectangular flat surface on the back of the
input diode.
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. Remove the small jumpers from the component
being replaced and transfer them to the replace-
ment component.
b. 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.