Yanmar 4LHA-HTP Operation Manual page 667

Chapter 9 Electrical System
7. Tachometer
7-3 Measurement of sensor unit characteristics
(1) Measurement of output voltage
Output voltage
Measuring conditions
Number of teeth of
ring gear
Gap between the ring
gear and sender
Resistance
Speed of ring gear
Measuring temperature
Measuring instrument
7-4
Fault
Does not function well.
1) Pointer does not move.
2) Functions intermittently.
1.0V or higher
IV or higher
127
1.3mm (0.0511 in.)
20kQ
500 rpm (approx. 800Hz)
20 C(68 F)
0 0
Synchroscope
Diagnosis
Check if there is an open-circuit cable connection at the
rear of the meter, a loose or disconnected terminal, or bad
continuity due to corrosion.
Disconnect at the instrument terminals, and measure the
vottage between the cable terminals. (To be 10 ~ 16V)
Rotation detecting sender
'Check the output wave pattern and number of pulses
when carrying out the output voltage measurement.
(2) Measurement of internal resistance
Measuring conditions
Measuring temperature
Measuring instrument
Rotation detecting sender
am
1 Satisfactory
9-41
Synchroscope
1.3mm
20 C(68 F)
< , , ,
Digital tester
Digital tester
I 1 600 I
Remedy
Yes Make good the connection.
If the input voltage is
No
abnormal, check the cause,
(e.g. short-circuit, disconnec-
tion, or blown fuse, etc.)
4LHA Serie
AC 100V