Troubleshooting & repair – Lincoln Electric IDEALARC CV-300 User Manual
Page 75
F-36
TROUBLESHOOTING & REPAIR
F-36
IDEALARC CV-300
PROCEDURE
1.
Loosen the appropriate diode nut
and remove the diode that is to be
replaced.
2.
Clean the area on the heat sink
around the diode mounting surface
using a putty knife, or similar tool,
DO NOT SCRATCH THE DIODE
MOUNTING SURFACE.
3.
Polish each heat sink's mounting
surface using NO. 000 fine steel
wool. Wipe surface clean with a lint
free cloth or paper towel.
4.
Inspect the mounting surfaces of
each new diode. Remove all burrs
and wipe clean. Do not use steel
wool or any abrasive cleanser on
the diode mounting surface.
5.
Apply a thin (0.0003" to 0.0007")
uniform layer of E1868 (Dow
Corning 340) heat sink compound to
the heat sink mounting surface.
a.
Do not apply compound to diode
stud or mounting threads.
b.
The diode threads must be
clean and free of defects so that
the nut can be finger tightened
before applying torque. A "slip"
type torque wrench must be
used to tighten the diode nut.
6.
Tighten the diode nuts to the specifi-
cations in the following table.
a.
The nuts for diodes with steel
studs are to be started by hand
and then torqued as per the fol-
lowing table.
b.
The nuts for diodes with copper
studs are to run on all the way
by hand then torqued as per the
following table.
c.
Turn a minimum of 1/2 turn
more while torquing per the
table.
MOUNTING OF STUD TYPE DIODES TO ALUMINUM HEAT SINKS (CONT’D)
DIODE STUD
SIZE
3/4 - 16
3/8 - 24
1/4 - 28
FOOT-
POUNDS
25-27
10±.5
INCH-
POUNDS
300-324
125+0/-5
22-25