Instruction manual

Easy-Start ES Instruction Manual
Troubleshooting
SECTION 5
5-11
SCR Diagnostic Tests
Changing Isolated Block SCRÕs:
The following procedure can be used for
changing isolated block SCRÕs.
1. Remove the printed circuit logic board.
2. Remove the power and control connections
from the SCR and identify the wires.
3. Remove the SCR block.
4. Before installing the new SCR block, the old
thermal compound and any foreign matter
should be removed from the heat sink mating
surface. If necessary, use an extra fine grit
emory cloth to smooth the heat sink surface.
Coat the bottom surface of the SCR block
with a thin coat of thermal compound (Alcoa-
2 or an equivalent electrical joint compound).
Wipe off the excess compound.
Notice - Use sparingly - Apply only a thin coat of
compound.
5. Place the SCR block into position on the heat
sink. Insert bolts and tighten them finger
tight, or use a wrench until all the bolts are
just snug. Tighten the bolts alternately in
quarter-turn increments until the SCR block is
tight. Keep equal pressure on all the
mounting hardware. Visually inspect the
SCR block to make sure it's lying flat on the
heat sink.
6. Securely fasten the power and control wiring
on the SCR block. Tug on the leads gently to
make sure there are no loose connections.
Check to make sure the SCR block is wired
with the correct polarity.