WACKER Group LTC 4, Repair Manual

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Electrical Troubleshooting Procedures LTC Repair
wc_tx000429gb.fm
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7.24 Restoring Rotor Magnetism (Flashing) / Checking Rotor
Winding
See Graphic: wc_gr002171
Electric shock hazard. Only qualified personnel should conduct this
test.
These procedures require two 14-gauge jumper wires and a fully-
charged 12V battery.
If you measured 0 (zero) volts at the main circuit breaker, the generator
may have lost its residual magnetism. Try restoring the magnetism
(flashing) to the generator before conducting in-depth tests. Flashing
the generatior serves two purposes: 1) it restores rotor magnetism and
2) it confirms a working rotor (winding and diodes). By flashing the
generator with a known DC voltage, a predictable output voltage is
produced. For example, using a 12-volt battery, produces an output
voltage of 30–40 volts. Flash the generator before disassembly to
confirm a malfunctioning rotor.
Start this test with the engine shut down.
7.24.1 Unplug the #60 and #0 leads from the generator capacitor.
7.24.2 Using 14 gauge or larger wire, connect two jumper wires to the battery,
one to each terminal. Once connected to the battery, do not allow the
two jumpers to touch each other.
Explosion hazard. Do not create sparks near battery.
7.24.3 Start the engine.
7.24.4 Connect the opposite end of the jumper wires to the #60 and #0
leads—connect either wire to either lead. This is a non-polar
connection.
7.24.5 Using the AC voltage setting on the multimeter, check the voltage
across the terminal strip mounted on the generator: red (T5) to white
(T4); black (T1) to white (T4). There should be 30–40 volts measured
in both cases.
• If you measure 30–40 volts, the generator is functioning. Shut down
the machine and disconnect the jumpers, first at the capacitor wires,
then at the battery.
• If you do not measure 30–40 volts, there is a problem. Shut down the
engine and continue troubleshooting. See section Checking Stator
Windings.
WARNING
WARNING