1. SR4 principle Field L3 Diode T0 T1 T2 T3 L4 Stator L1 L2 Armature

2. SE or PM Self exited Permanent magnet Remaining magnetism
Field L3 L4
Stator
Diode L1 L2
Armature
Remaining magnetism
Permanent
magnet T0 T1 T2 T3
Field L3 L4
Stator
Diode L1 L2
Armature
Permanent magnetism L5

3. Self exited schematic - +L3 L4 RFA L2 L1 Field L3 Diode T0 T1 T2 T3 L4
Stator
Diode L1 L2
Armature

4. Permanent magnet schematicL4 T0 T1 T2 T3
Field L3 L4
Stator
Diode L1 L2
Armature L5
+L3 -
RFA L2 L1 S N L5

5. Flashing the field
If the generator rotating field (L5) or the exciter field (L3) have a loss of residual magnetism the magnetism can be put back by flashing the exciter field winding with a direct current source.
DYNAMIC FLASHING (ENGINE RUNNING)
With the engine stopped , connect a voltmeter to terminal 20 and 22 . Connect the positive cable of the DC source to terminal F1. Start the engine and run at low idle rpm . Put the negative cable of the DC source on terminal F2 while reading the voltmeter. AS SOON AS THE VOLMETER HAS AND INDICATION OF VOLTAGE, REMOVE THE NEGATIVE CABLE FROM TERMINAL F2
STATIC FLASHING (ENGINE STOPPED)
With the engine stopped , disconnect exciter filed (L3) wires from terminal F1 and F2 of the voltage regulator. Connect the positive cable of the DC source to wire F1 and negative to wire F2 for NO MORE THAN ONE OR TWO SECONDS. Repeat 2 or three times.
According to theory this method has the effect of putting residual magnetism back in the exciter.

6. - Rectifier block + AC3 AC2 AC1 Varistor CR7 AC2 AC1 AC3 CR1 CR2 CR3

7. - Rectifier block test Rectifier test +
1- Multimeter on range
2- Remove all wires from block
3-Black test lead on Pos. terminal
AC1
Red lead on AC2
AC3
Measure between
0.4 & 1.0 volt
AC3
AC2
AC1 + -
4- Reverse leads : Measure OL on all position
5-Black test lead on Neg.. terminal
AC1
Red lead on AC2
AC3
Measure OL
6- Varistor test: Measure resistance between Pos. & Neg. : Measure 15K or more