Installation manual
TACHOMETER
TACHOMETER/HOUR
METER
The tachometer/hour 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 tl,e alternator and supplied
to
the
tachometer
input
terminal
while
the
engine
is
mnning,
and
the alternator producing battery charging voltage 13.0-14.8
volts
DC.
The following me procedures
to
follow when troubleshoot-
ing
a
fault
in
either
of
the
two
circuits
in
a
tachometer/hour
meter.
Hour
Meter
Inoperative
Check for the proper DC voltage between (+) and (-)
terminals.
1.
Voltage present - meter
is
defective - repair or replace.
2. Voltage not present - ttace
(+)
and
(-)
electrical
connections for fault. (Jump
12
valls
DC
to meter (+)
terminal to verify the operation.)
Tachometer
Inoperative
Check for the proper AC voltage between tachometer input
tenninal
and
(-)
temlinal
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 terminal on alternator
to
ground.
4.
Check
electrical connections
from
tachometer
input
tenninal
to
alternator
connection.
Tachometer
Sticking
1.
Check for proper AC voltage between "tach inp."
terminal and (-) tennina!.
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
coal'S
adjustment, select
A,
B, 4, 6, or 8 that
puts tile panel tachometer rpm reading the closest to the
strobes
tachometers
rpm
reading.
c.
Using a 5/64 (2mm) allen wrench, adjust the calibration
pod
on
the
panel
tachometer
to
read
the
same
as
the
strobe
tachometers
rpm.
COARSE
ADJUSTMENT
TACHOMETER
CHECK
(New
Installation)
TERMINAL
TERMINAL
NOTE:
In
a
new
installation
having
new
instrumellt
panels,
the
tachometer
may
n.ot
always
be
correctly calibrated
to
the
engine
s
rpm.
This
calibration
should
be
checked
in
all
n.ew
installations.
1.
Warm
up
the
engine
to
nonnal
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 photoelectlic type tachometer.
2.
Start and idle the engine.
3. Aim the light of the tachometer onto the reHecting 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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WESTERBEKE
EngInes & Generators
23