C.E. Niehoff & Co. N1601/N1602/N1603/N1604 Troubleshooting Guides - Manual (Page 5)

Page 5 TG29D
Section C: Advanced Troubleshooting
N3223 Regulator
DESCRIPTION AND OPERATION
N3223 regulator with OVCO is attached directly to
the outside of alternator. Regulator setpoint has flat
temperature compensation. Voltage setpoint is 28.0
±1.0 V and 14.0 ±0.5.
Main diagnostic feature of regulators consists of two
tricolored (red, amber, green) LEDs located on the
side of the regulator. One LED indicates 28 V system
performance, the other LED indicates 14 V system
performance. The two LEDs work independently of
each other. See Table 2 for diagnostic features and
LED explanations.
OVCO (overvoltage cutout) operation:
• 14 V side trips at voltage
higher than regulator
setpoint that exists longer than 3 seconds of reading
voltage above 16 V. OVCO feature detects overvoltage
and reacts by disabling the alternator field circuit.
This turns off alternator (14 V LED is steady RED
light). OVCO circuit will reset automatically when:
— restarting engine
OR
— system voltage falls below 11 V.
• 28 V side trips at voltage higher than regulator
setpoint that exists longer than 3 seconds of reading
voltage above 32 V. OVCO feature detects overvoltage
and reacts by disabling the alternator field circuit.
This turns off alternator (28 V LED is steady RED
light). OVCO circuit will reset automatically when:
— restarting engine
OR
— system voltage falls below 22 V.
Advanced Troubleshooting
Shut down vehicle and restart engine. If alternator
functions normally after restart, a “no output condition”
was normal response of voltage regulator to overvoltage
condition. Inspect condition of electrical system, includ-
ing loose battery cables, both positive and negative.
If battery disconnects from system, it could cause over-
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, overvoltage spike that caused
OVCO circuit to trip.
N3223 only: If OVCO circuit repeats cutout a second
time in short succession and shuts off alternator field
circuit, try third restart. If OVCO circuit repeats cutout
a third time, check color of LED while engine is running
and go to Chart 3a or 3b, page 8.
Other regulators: If OVCO circuit repeats cutout a
second time in short succession and shuts off alternator
F– circuit, try third restart. If OVCO circuit repeats
cutout, go to Chart 3 on page 8; or for N1604, go to
chart 5 on page 10.
LED COLOR STATUS
TABLE 2 – N3223 Regulator LED Operation Modes
No AC/rotation. See Chart 1 on page 6 for 28 V systems, Chart 2 on page 7 for 14 V systems.
Alternator is shut down and is not producing power for either voltage. 28 V side trips after 3 seconds of
reading voltage above 32 V. 14 V side trips after 3 seconds of reading voltage above 16 V. Regulator remains
in this mode until reset by restarting engine or if system voltage drops below 22 V or 11 V, respectively.
See Chart 3a or 3b on page 8.
FLASHING
Amber
Red
STEADY
Green
Amber
Respective system voltage is at regulated setting and operating under control.
Respective system voltage is below regulated setting. Alternator is not producing power or circuit is over-
loaded. See Chart 1 on page 6 for 28 V systems, Chart 2 on page 7 for 14 V systems.