Tachometer - Subaru 1600 Service Manual

• Tachometer
1) Specifications
Range of indication
Resolving power of
indication
Cycle of indication
Accuracy of indication
Hysteresis of indication
Input signal
Warning function
Display element
ELECTRICAL SYSTEM
0- 8,000 rpm.
Below 1,000 rpm.: Pitch of 50 rpm.
Over 1,000 rpm.: Pitch of 100 rpm.
0.3 - 0.33 second
±100 rpm. ±200 rpm. at over 1,000 rpm.
below 4,000 rpm.
50 rpm. 100 rpm. at over 1,000 rpm.
4-cylinder, ignition pulse
Buzzer sounds at over 5,500 rpm. (4 Hz ± 5%)
In addition, bar lights (Red) under the figures
of tachometer turns on.
4-figure digital indication by fluorescent display
tubes
._-
2) Operation
Signals from the minus (-) side of the
ignition coil are modified in waveform.
The number of pulses entered in a
given time is counted by the counter
circuit of the microcomputer, and is
memorized by the memory circuit.
The memorized data is transferred to
the display circuit every 0.3 seconds,
displaying the engine rpm. on the
fluorescent display tubes.
I
Ignition pulse
II------t~=l
Waveform modification
:1---..-1
Microcomputer
I
~---,-----~
3) Indicant standard
Standard tachometer
500 1,000 2,000
indication (rpm.)
Tolerable error of
500 ± 100 1,000 ± 200 2,000 ± 200
indication (rpm.)
15-50
'1"
Indication drive circuit
3,000
3,000 ± 200
Fluorescent display
tubes
4,000 5,000
4,000 ± 300 5,000 ± 300
6,000
6,000 ± 300