C.E. Niehoff & Co. N1241-1 Troubleshooting Guides - Manual (Page 4)

Page 4
TG0043B
N3208 Regulator
DESCRIPTION AND OPERATION
N3208 Regulator with OVCO is attached directly to
the outside of alternator. Regulator setpoint has
negative temperature compensation. At 75ºF, the
setting is 28.2 V for 28 V system and 14.1 V for 14 V
system.
Main diagnostic feature of N3208 regulator 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 indepen-
dently of each other. See Table 2 for diagnostic
features and LED explanations.
OVCO (overvoltage cutout) will trip at any of the
following conditions:
• 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 signaling relay in F–
alternator circuit to open. This turns off alterna-
tor (14 V LED is steady RED light). OVCO circuit
will reset by restarting engine (regulator regains
control of alternator output voltage).
• 28 V side trips at voltage higher than regulator
setpoint that exists longer than 2 seconds of
reading voltage above 32 V. OVCO feature detects
overvoltage and reacts by signaling relay in F–
alternator circuit to open. This turns off alterna-
tor (28 V LED is steady RED light). OVCO
circuit will reset by restarting engine (regulator
regains control of alternator output voltage).
TROUBLESHOOTING
Shut down vehicle and restart engine. If alternator
functions normally after restart, a “no output condi-
tion” was normal response of voltage regulator to
overvoltage condition. Inspect condition of electrical
system, including loose battery cables, both positive
and negative. If battery disconnects from system, it
could cause overvoltage 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.
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 a third
time, check color of LED while engine is running.
28 V RED LED - go to Chart 3, page 6.
14 V RED LED - go to Chart 4, page 6.
LED COLOR STATUS
TABLE 2 – N3208 Regulator LED Diagnostics
Regulator is not energized. Measure E terminal voltage. If voltage above 21 V, alternator-to-
regulator harness is unplugged or regulator is defective. OFF
Section 3: Advanced Troubleshooting
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 overloaded. See Chart 1 on page 5 for 28 V systems, Chart 2 for 14 V systems.
Respective system voltage is above regulated setting. This may occur intermittently with voltage
transients or with system faults.
FLASHING
Green
Amber
STEADY
Amber
Red AC signal is lost.
Alternator is shut down and is not producing power for either voltage. 28 V side trips after
2 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. See Chart 3 on page 6 for
28V systems, Chart 4 for 14 V systems.
Red