WAVE PATTERN CHECK USING AN OSCILLOSCOPE

MEASUREMENT METHOD

Connect the oscilloscope special patterns pick-up to the generator "B" terminal.

STANDARD WAVEFORM

Observation Conditions
FUNCTION	SPECIAL PATTERNS
Pattern height	Variable
Variable knob	Adjust while viewing the wave pattern
Pattern selector	Raster
Engine revolutions	Curb idle speed

note

The voltage waveform of the generator "B" terminal can undulate as shown at left. This waveform is produced when the regulator operates according to fluctuations in the generator load (current), and is normal for the generator.
If the ripple height is abnormally high (approximately 2 V or more during idling), the wires between the generator "B" terminal and the battery have broken due to fuse blowing, etc. The generator is usually operating properly.

ABNORMAL WAVEFORMS EXAMPLES

note

The size of the waveform patterns can differ greatly, depending on the adjustment of the variable knob on the oscilloscope.

note

Identification of abnormal waveforms is easier when there is a large output current (regulator is not operating). (Waveforms can be observed when the headlights are illuminated.)

note

Check the conditions of the generator malfunction light (illuminated/not illuminated) also, and carry out a total check.

ABNORMAL WAVEFORMS <Non-turbo>

Example 1
PROBABLE CAUSE: Open circuit in diode
Example 2
PROBABLE CAUSE: Short-circuit in diode
Example 3
PROBABLE CAUSE: Open circuit in stator coil
Example 4
PROBABLE CAUSE: Short-circuit in stator coil

ABNORMAL WAVEFORMS <Turbo>

Example 1
PROBABLE CAUSE: Open circuit or short circuit in diode
Example 2
PROBABLE CAUSE: Open circuit in stator coil (In stator coil)
Example 3
PROBABLE CAUSE: Open circuit in stator coil (Open circuit between stator coil and diode)
Example 4
PROBABLE CAUSE: Short circuit in stator coil