Installation manual

TACHOMETER
TACHOMETER/HOUR METER
The tachometerlhour meter used in propulsion engine
instrument panels contains
two separate electrical circuits
with a common ground.
One circuit operates the hour meter
and the other the tachometer. The hour meter circuit operates
on 12 volts alternator charging voltage supplied to the (+)
tenninal on the back of the instrument.
The tachometer circuit operates on AC voltage 6-8 volts, fed
from one of the diodes
in the alternator and supplied to the
tachometer input tenninal while the engine is running, and
the alternator producing battery charging voltage 13.0-14.8
volts
DC.
The following are procedures to follow when troubleshoot-
ing a fault in either of the two circuits in a
tachometerlhour
meter.
Hour Meter Inoperative
Check for the proper DC voltage between (+) and (-)
tenninals.
1. Voltage present - meter is defective - repair or replace.
2. Voltage not present - trace
(+) and (-) electrical
connections forfault. (Jump 12 volts DC
to meter (+)
tenninal to verify the operation.)
Tachometer Inoperative
Check for the proper AC voltage between tachometer input
tenninal and
(-) tenninal with the engine running.
1. Voltage present - attempt adjusting meter through
calibration access hole. No results, repair or replace
meter.
2. AC voltage not present - check for proper alternator DC
output voltage.
3. Check for AC voltage at tach tenninal on alternator
to
ground.
4. Check electrical connections from tachometer input
terminal
to alternator connection.
Tachometer Sticking
1. Check for proper AC voltage between "tach inp."
tenninal and (-) terminal.
2. Check for good ground connection between meter
(-)
tenninal and alternator.
3. Check that alternator is well grounded to engine block at
alternator pivot bolt.
Tachometer Inaccurate
a. Using a hand held strobe tachometer reading front crank
shaft pulley speed. Adjust the engine speed to
112 rated
engine rpm ..
b. Using the coars adjustment, select A, B, 4, 6, or 8 that
puts the panel tachometer rpm reading the closest to the
strobes tachometers rpm reading.
c. Using a 5164 (2mm).allen wrench, adjust the calibration
pod on the panel tachometer to read the sarne as the
strobe tachometers rpm.
COARSE
ADJUSTMENT
TACHOMETER CHECK (New Installation)
TERMINAL
NDTE: In a new installation having new instrument panels,
the tachometer may not always be correcJly calibrated to the
engine's rpm. This calibration should be checked in all new
installations.
1. Warm up the engine to normal operating temperature.
Remove any specks on the crankshaft pulley with a clean
cloth and place a piece of suitable reflecting tape
on the
pulley
to facilitate use of a photoelectric type tachometer.
2. Start and idle the engine.
3. Aim the light of the tachometer onto the reflecting tape
to confirm the engine speed. Check the instrument panel
tachometer reading. Adjust the tachometer
in the panel
by using the instrument coarse adjustment to calibrate the
instrument reading to the closest rpm that the photo tach
is showing. Then use the fine calibration adjustment to
bring the instrument to the exact reading as the photo
tach.
4. Set the tachometer to the idle speed (the engine
idle' speed
has been factory adjusted and the idle screws and high
speed screws have been locked in place).
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WESTERBS
Engines & Gen.erator
27