C.E. Niehoff & Co. N1450 Troubleshooting Guides

C.E. Niehoff & Co.
Troubleshooting Guide
for N1450 Alternators
Hazard Defi nitions
CAUTION
will or can cause minor personal injury or property damage.
Indicates special instructions on installation, operation or mainte-
NOTICE
nance that are important but not related to personal injury hazards.
Table of Contents
Section A: Wiring Diagram ......................................2
Section B: Basic Troubleshooting ............................3
Section C: Advanced Troubleshooting ................ 4 – 5
Battery Conditions
Until temperatures of electrical
NOTICE
system components stabilize, these conditions may be observed during cold-start voltage tests.
Maintenance/Low Maintenance Battery
— Immediately after engine starts, system volts are lower than regulator setpoint, amps are medium. — 3–5 minutes into charge cycle, system volts increase, amps decrease. — 5–10 minutes into charge cycle, system volts increase to, or near, regulator setpoint and amps decrease to a minimum. — Low maintenance battery has same characteristics with slightly longer recharge times.
Maintenance-free Battery
— Immediately after engine starts, system volts are lower than regulator setpoint, low charging amps. — Once charge cycle begins, low volts and low amps are still present. — After alternator energizes, voltage will increase several tenths. Amps will increase gradually, then quickly, to medium to high amps. — F i n a l l y , v o l t s w i l l i n c r e a s e t o s e t p o i n t a n d a m p s w i l l decrease. The time it takes to reach optimum voltage and amper­age will vary with engine speed, load, and ambient temperature.
High-cycle Maintenance-free Battery
These batteries respond better than standard mainte­nance-free. Charge acceptance of these batteries may display characteristics similar to maintenance batteries.
AGM (Absorbed Glass Mat) Maintenance-free Battery
These dry-cell batteries respond better than standard maintenance-free. If battery state of charge drops to 75% or less, batteries should be recharged to 95% or higher separately from the engine’s charging system to avoid damaging charging system components and to provide best overall performance. Charge acceptance of these batteries may display maintenance batteries.
characteristics similar to
Battery Charge Volt and Amp Values
Volt and amp levels fluctuate depending on the battery state of charge. If batteries are in a state of discharge—as after extended cranking time to start the engine—system volts will measure lower than the regulator setpoint after the engine is restarted and system amps will measure higher. This is a normal condition for the charging system; the greater the battery discharge level, the lower the system volts and the higher the system amps. The volt and amp readings will change as batteries recover and become fully charged: system volts will increase to regulator setpoint and system amps will decrease to low level (depending on other loads).
Low Amps: Minimum or lowest charging system amp
value required to maintain battery state of charge, obtained when testing the charging system with a fully charged battery and no other loads applied. This value will vary with battery type.
Medium Amps: System amps value which can cause
the battery temperature to rise above adequate charging temperature within 4-8 hours of charge time. To pre­vent battery damage, the charge amps should be re­duced when battery temperature rises. Check battery manufacturer’s recommendations for proper charge amp rates.
High Amps: System amps value which can cause
the battery temperature to rise above adequate charging temperature within 2-3 hours of charge time. To pre­vent battery damage, the charge amps should be re­duced when battery temperature rises. Check battery manufacturer’s recommendations for proper charge amp rates.
Battery Voltage: Steady-state voltage value as mea-
sured with battery in open circuit with no battery load. This value relates to battery state of charge.
Charge Voltage: Voltage value obtained when the
charging system is operating. This value will be higher than battery voltage and must never exceed the regula­tor voltage setpoint.
B+ Voltage: Voltage value obtained when measuring
voltage at battery positive terminal or alternator B+ terminal.
Surface Charge: Higher than normal battery voltage
occurring when the battery is disconnected from battery charger. The surface charge must be removed to determine true battery voltage and state of charge.
Significant Magnetism: Change in strength or inten-
sity of a magnetic field present in alternator rotor shaft when the field coil is energized. The magnetic field strength when the field coil is energized should feel stronger than when the field is not energized.
Voltage Droop or Sag: Normal condition occurring
when the load demand on alternator is greater than rated alternator output at given rotor shaft RPM.
TG57B
Page 1
Section A: Wiring Diagram
CEN N1450 Alternator Description and Operation
N1450 28 V (400 A) alternator is internally rectified. There are no brushes or slip rings to wear out. Energize switch activates regulator. Exciter stator is then energized.
After engine is running, the regulator receives energize signal. Regulator monitors alternator rotation and pro­vides field current only when it detects alternator shaft rotating at suitable speed.
N3227 or N3250 regulator used with some units:
• is negative temperature compensated.
• maintains alternator output voltage at regulated settings as vehicle electrical loads are switched on and off.
provides overvoltage cutout (OVCO). Regulator will trip OVCO when system voltage rises above 32 V for longer than 3 seconds. OVCO feature detects high voltage and reacts by disconnecting field and turning off alternator. Restarting engine or waiting until system voltage drops below 24 V will reset OVCO circuit.
B– terminal
B+2 secondary (low load) output terminal
B+1 primary (high load)
output terminal. Battery must be connected to this terminal for unit to be energized.
Figure 1 — N1450 Alternator Terminals
Page 2
Figure 2 — N1450 Wiring Diagram
TG57B
Section B: Basic Troubleshooting
Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
Identifi cation Record
List the following for proper troubleshooting:
Alternator model number _________________________
Regulator model number ________________________
Setpoint listed on regulator ______________________
Preliminary Check-out
Check symptoms in Table 1 and correct if necessary.
TABLE 1 – System Conditions
SYMPTOM
Low Voltage Output
High Voltage Output
No Output
Check: low battery state of
charge.
Check: current load on system
is greater than alternator can produce.
Check: defective wiring or poor
ground path; low regu­ lator setpoint.
Check: defective alternator or
regulator. Check: wrong regulator. Check: high regulator setpoint. Check: defective regulator. Check: alternator. Check: battery voltage at alter-
nator output terminals. Check: defective alternator
or regulator.
ACTION
4. Connect meters to alternator Connect red lead of DMM to B+ terminal(s) and
black lead to alternator B– terminal. Clamp induc­ tive ammeter(s) on B+ cable(s).
5. Operate vehicle Observe charge voltage at batteries with engine running (nom. 27-28 V).
If charge voltage is above 32 V, immediately shut down system. Electrical system damage may occur if charging system is allowed to operate at excessive voltage. Go to Table 1.
If voltage is at or below regulator setpoint, let
charging system operate for several minutes to normalize operating temperature.
6. Observe charge volts and amps Charge voltage should increase and charge amps should decrease. If charge voltage does not in­ crease within ten minutes, continue to next step.
7. Batteries are considered fully charged if charge voltage is at regulator setpoint and charge amps remain at lowest value for 10 minutes.
8. If charging system is not performing properly, go to Chart 1, page 4.
9. Check OVCO circuit Shut down vehicle and restart engine. If alternator functions normally after restart, a “no output condition” was a normal response of voltage regulator to “high voltage” condition. Inspect condition of electrical system, including loose battery cables, both positive and negative. If battery disconnects from system, it could cause “high voltage” condition in electrical system, causing OVCO circuit to trip.
If you have reset alternator once, and electrical
system returns to normal charge voltage condition, there may have been a one time, high voltage spike, causing OVCO circuit to trip.
If OVCO circuit repeats cutout a second time in
short succession, try third restart. If OVCO circuit repeats cutout, go to Chart 2, page 5.
CAUTION
Basic Troubleshooting
1. Inspect charging system components for damage
Check connections at B– cable, B+ cables, and alternator-to-regulator harness. Repair or replace any damaged component before troubleshooting.
2. Inspect all vehicle battery connections
Connections must be clean and tight.
3. Determine battery voltage and state of charge If batteries are discharged, recharge or replace batteries as necessary. Electrical system cannot be properly tested unless batteries are charged 95% or higher. In addition, open circuit voltages must be within ± 0.2 V.
TG57B
Page 3
Section C: Advanced Troubleshooting
Chart 1 – No Alternator Output – Test Charging Circuit
Shut down vehicle and restart engine or wait until system voltage drops below 28 V. Does alter­nator function normally after restart?
Yes
No
Regulator responded to overvoltage condition. Go to Chart 2 on page 5 to troubleshoot OVCO.
Shut off engine. With key off, engine off: Test for battery voltage at alternator B+1 terminal connected to battery. Does battery voltage exist?
Yes
No
Repair vehicle battery circuit wiring as necessary. Continue test.
Disconnect 3-socket harness plug from regulator. With key on, engine running: Test for battery voltage between pin B in 3-pin connector on regulator and alternator B– terminal. Does battery voltage exist?
Yes No
Repair vehicle ignition circuit wiring as necessary. Continue test.
MASTER BATTERY SWITCH OFF, KEY OFF, ENGINE OFF: Reconnect 3-socket harness to regulator. Discon­nect alternator-to-regulator harness at regulator. Follow static tests in Table 2. Has any test result failed?
Alternator should not be powered during static tests. Connections required during
WARNING
testing can cause shorts and damage alternator.
TABLE 2 Pin-to-Pin Tests (See Figure 3)
DISCONNECT ALTERNATOR-TO-REGULATOR WIRING HARNESS AT REGULATOR.
TESTS MUST BE PERFORMED AT ROOM TEMPERATURE.
1
2
3
4
5
6
7
8
9
10
11
12
13
METER SCALE
& SYMBOL
Ohms Ω
Ohms Ω
Ohms Ω
Ohms Ω
Ohms Ω
Diode Test
Diode Test
Diode Test
Diode Test
Diode Test
Diode Test
Continuity
Continuity
TEST
NO.
* Meter will show OL when capacitors are fully charged and readings stabilize. ** Meter will show voltage drop of all diodes in parallel when capacitors are fully charged and readings stabilize.
NOTE 1: If PC board is present , <0.7 volt (flow). If not present, <0.3 volt (f low).
METER (+) LEAD
CONNECTION
Pin J
Pin M
Pin L
Pin E
Pin G
Alt. B– Terminal
Alt. B– Terminal Alt. B+ 1 Termina l
Alt. B– Terminal Alt. B+ 2 Termina l
Alt. B– Terminal
Pin A Alt. B+ 1 Termina l
METER (–) LEAD
CONNECTION
Pin K
Alt. B– Terminal Alt. B+ 1 Termina l Alt. B+ 2 Termina l
Pin H
Pin A
Pin B
Alt. B– Terminal Alt. B+ 1 Termina l
Alt. B– Terminal Alt. B+ 2 Termina l
Pin B Alt. B+ 2 Termina l
TESTED CIRCUIT
Field circuit
Ground circuit Power circuit (B+ 1) Power circuit (B+ 2)
Stator temp sensor Phase circuit (P1)
Phase circuit (P2) All diodes in parallel (B+ 1) All diodes in parallel (B+ 1) All diodes in parallel (B+ 2) All diodes in parallel (B+ 2)
Stator-to-stator continuity B+ 1 to B+ 2 continuity
Yes
Alternator is defective.
Replace regulator with known good regulator. Run engine. Does no-output condition still exist?
Yes
Alternator is defective.
EXPECTED
READING
5–6 ohms
<1 oh m
<1 oh m
<1 oh m
90K to 120K ohms
See NOTE 1
See NOTE 1
OL*(blocking)
<0.7 volt**(flow)
OL*(blocking)
<0.7 volt**(flow)
OL (blocking)
OL (blocking)
No
No
Regulator is defective.
Page 4
TG57B
Section C: Advanced Troubleshooting (CONT’D)
Chart 2 – No Alternator Output – Test OVCO Circuit
Unplug alternator-to-regulator harness from regulator. Connect red lead from DMM to pin J in plug. Connect black lead to pin K in plug. Does resistance read 5-6 ohms?
Yes
No
Alternator is defective.
With red lead from DMM connected to pin K in plug, connect black lead to B– terminal. Does resistance read OL (out of limits)?
Yes
Replace existing regulator with known good regulator. Run engine. Does OVCO trip?
Yes
Alternator is defective.
ALTERNATOR CONNECTOR
A AC 1 G T+ 1 B AC 2 H T– 1 C  Not used J  F+ D  Not used K  F– E  B+ 2 L  B+ 1 F  Not used M  B–
Original regulator is defective.
PIN CONNECTIONS
No
Alternator is defective.
B– terminal
No
Figure 3 – Alternator-to-Regulator
Harness Plug
B+ 1 primary (high load) output terminal. Battery must be connected to this terminal for unit to be energized.
B+ 2 secondary (low load) output terminal
If you have quest ions about your a lternator or a ny of these test procedures, or if you need to locate a Factory Authorized Serv ice Dea ler, please contact us at:
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
TEL: 800.643.4633 USA and Canada • TEL: 847.866.6030 outside USA and Canada • FAX: 847.492.1242
E-mail us at service@CENiehoff.com
TG57B
Page 5
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