C.E. Niehoff & Co. N1388, N7153 Instructions
N1388 Alternator
N7153 Control Unit Assembly
and/or N7155 B+ Terminal
Replacement Instructions
1. Remove hardware and cover plates from:
a. top of control unit
b. front of control unit
c. drive end housing
2. Remove and save voltage adjust plug from control
unit assembly (this step is not necessary when
replacing B+ terminal).
3. Carefully remove potting in front of terminal strip
in control unit to expose six terminals.
4. Disconnect two field coil wires, B+ wire, ground
wire, two stator Y-taps, and phase (AC) wire from
terminal strip.
5. Remove and save the hardware attaching the control
unit assembly.
6. Carefully dig out all of the potting inside the control
unit cavity. DO NOT DESTROY ANY INTERNAL
WIRING.
7. Remove control unit assembly from cavity.
8. Clean out any loose debris in exposed cavity hole
and from wire terminals that will be reattached to
the control unit assembly.
9. Replacing control unit assembly ONLY—proceed
to step 19 on page 2.
Replacing B+ terminal—proceed to step 10 at
right.
Control unit assembly
V
Follow steps 10-18 below to complete B+ terminal
replacement:
10. Remove and save hardware and stud on external B+
terminal.
11. From internal B+ stack, disconnect hardware,
B+ wire, and two rectifier wires.
12. Remove and save hardware attaching the defective
B+ terminal to the housing.
13. Remove defective B+ terminal.
14. Apply bead of Dow Corning® SE9186L RTV
coating or equivalent on mating surfaces between
new B+ terminal plate and drive end housing.
15. Install new B+ terminal in cavity. Use a suitable
adhesive such as Loctite® 222 on three mounting
screws. Torque mounting screws to 4.8 Nm/40 lb. in.
16. Using sandpaper and a cloth, remove all potting
debris from both rectifier wire terminals and B+
wire terminal to ensure the mating faces make
clean contact with each other.
17. Reconnect wiring removed from internal B+ stack in
step 11 according to the stacking order shown in
Figure 2. Torque to 28.2-29.3 Nm/20.3-21.6 lb. ft.
18. Proceed to step 19 on page 2 to complete assembly.
B+
terminal
B+
wire
V
Bolt
V
B+ wire
Phase
(AC) wire
V
Ground wire
V
Two fi eld coil wires
V
V
V
V
Two stator
Y-taps
Figure 1 – Replacing Control Unit Assembly and/or
B+ Terminal on N1388 Alternator
Page 1 of 2
Two
rectifi er
wires
Flat
washer
voltage
adjust
plug
V
Figure 2 – Internal B+ Stacking Order
Disc
spring
washer
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19. Apply bead of Dow Corning® SE9186L RTV coating
or equivalent on mating surfaces between control
unit assembly and drive end housing.
20. Install control unit assembly in cavity. Use a suit able adhesive such as Loctite® 222 on screws.
Torque mounting screws to 2.3 Nm/20 lb. in.
21. Reconnect wiring removed from terminal strip.
See Figure 1 on page 1 and Figure 3 below.
Torque screws to 1.2 Nm/10 lb. in.
22. Apply bead of Dow Corning® SE9186L RTV
coating or equivalent on mating surfaces between
top control unit cover plate and drive end housing.
23. Re-install top control unit cover plate. Use a suit able adhesive such as Loctite® 222 on screws.
Torque mounting screws to 2.3 Nm/20 lb. in.
24. Turn alternator on anti-drive end and brace to
prevent movement. Press down all exposed wiring
so they will be covered by replacement potting.
25. Fill the cavity inside the control housing with GE
Silicones® RTV11® silicone 2-part system:
a. Mix 148 drops (0.1 ounce) of cure per 1 cup of
RTV. Mix well to prevent incomplete deep-set.
At this point, there is a half hour before mixture
thickens and two hours until mixture deep-sets.
b. Pour mixture into cavity until it covers the
terminal screws on the terminal strip. Make
sure all screws are covered with new potting
material.
Product warranty will be
void if cavity is not fi lled as
indicated in step 25.
26. When new potting is dry, re-install control unit
cover plate and drive end housing cover plate. Use
a suitable adhesive such as Loctite® 222 on screws.
Torque mounting screws to 2.3 Nm/20 lb. in.
27. Re-install voltage adjust plug in appropriate position
for use.
28. If B+ terminal was replaced, re-install external
hardware. Use a suitable adhesive such as Loctite®
222 on the middle of stud threads. Screw stud into
terminal until only 11/16" is protruding from surface of terminal. See Figure 4.
WARNING
Figure 3 – Reattaching Wiring to Terminal Strip
New potting
control unit
cover plate
V
V
Top
V
V
See step
28 above
V
Control unit
cover plate
Drive end
cover plate
V
Figure 4 – Replacing Control Unit Assembly and/or B+ Terminal on N1388 Alternator
C. E. Niehoff & Co. • 2021 Lee Street • Evanston, IL 60202 Tech Services Hotline 800-643-4633
Page 2 of 2
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