C.E. Niehoff & Co. C659 Troubleshooting Guides - Manual (Page 2)

Page 2 TG79A
Section A: Alternator and Regulator
CEN C659 Alternator with A2-146 Regulator
C659 (28 V, 260 A) alternator is internally rectified. All windings and current-transmitting components are non-moving,
so there are no brushes or slip rings to wear out.
This alternator becomes self-energized through internal diode trios. Residual magnetic field induces small voltage in sta-
tor and energizes field coil. Field coil continues receiving incremental voltage until full voltage is achieved.
AC is then rectified into DC output through diodes in drive end housing and supplied to the battery from the alternator
B+ terminal. See Figure 4 on page 3. Alternator output current is self-limiting and will not exceed rated capacity of
alternator. Regulator maintains alternator output voltage at pre-determined regulated setting (see Table 1 below for
setpoints) as vehicle electrical loads are switched on and off. Regulator maintains alternator output voltage at pre-deter-
mined regulated setting (see below for setpoints) as vehicle electrical loads are switched on and off.
A2-146 regulator has:
• P terminal that can provide optional AC voltage tap. P terminal signal frequency (Hz) x 10 = alternator shaft rpm.
• D+ terminal that can provide DC voltage signal to vehicle electrical system, confirming alternator operation.
Regulator fixed (flat temperature compensation) setpoints shown in Table 1 are selected based on battery type and are
temperature- or climate-dependent. Battery type selection and battery maintenance/function are the sole responsibilities
of the customer.
Figure 2—Voltage Setpoints
Table 1— Voltage Setpoint Switch Position
Voltage Setpoints (±0.2 V) Battery Type*
Position 1 27.5 V Maintenance
Position 2 28.0 V Maintenance
Position 3 28.5 V Maintenance-free
Position 4 29.0 V Maintenance-free
* Setpoint can depend on temperature or climate condition, as well as
battery type. If boiling or excessive gassing occurs with higher voltage
setpoint, change to next lower voltage setpoint.