TAH-97029N page 1of 4
Tachometer and Tachometer/Hourmeter Installation
Instructions for Series: ATS, ATHS, ATA, ATHA
TAH-97029N
Revised 01-04
Section 20
(00-02-0258)
Description
These tachometers are indicators of engine revolutions per minute (RPM). Models
equipped with hourmeter also record elapsed, engine running time.
The alternator driven models are designed to function from pulses generated by an alternator with 4, 8, 12, 14, or 16 poles on the rotor.
For magnetic sensor (pickup) driven models, the pulses can be obtained from the ring
gear of an engine by means of an electromagnetic sensor (pickup). Magnetic sensor
driven models are designed for flywheels having anywhere from 70 to 225 teeth.
All units are for negative ground, positive ground or isolated electrical systems. If the
instrument is connected reverse polarity, it will not operate until proper connections are
made. All units are powered by 12 VDC. For 24 VDC applications, a ATVC12/24 converter must be used (see Fig. 3 or Fig. 5).
Specifications
Power Input: 12 VDC (11.5 – 16 V) [0.84 to 1.44W].
Backlight: 3 to 4.7W
RPM Input Signal Voltage: 1.5 Vrms minimum from a magnetic pickup or
alternator (minimum 3-pole).
Accuracy: Tachometer:±2% full scale. Hourmeter: ±0.01% hours, ±1 count.
Temperature Range: -5°F to 185°F (-20°C to +85°C).
Dial (Face Plate): 270° sweep with white numerals (over black background)
Bezel: 304 Stainless Steel.
Scale: 0-3000 RPM and 0-4000 RPM (ATHA-40-12-A model only)
Case Material: Plastic.
Hourmeter Range: Measures elapsed time: 100,000 hours in 0.1 increments.
Basic Models
Magnetic Sensor (Pickup) Signal Tachometer 70 - 225 pulses 12 VDC
2733Hz to 13.62 kHz@3000 RPM
ATS-30-12 Tachometer w/ Bright Stainless Steel Bezel
ATS-30-12-A Tachometer w/ Black Stainless Steel Bezel
ATS-30-12-B Tachometer w/ SAE Bright Stainless Steel Bezel
ATS-30-12-C Tachometer w/ SAE Black Stainless Steel Bezel
ATHS-30-12 Tachometer/Hourmeter w/ Bright Stainless Steel Bezel
ATHS-30-12-A Tachometer/Hourmeter w/ Black Stainless Steel Bezel
ATHS-30-12-B Tachometer/Hourmeter w/ SAE Bright Stainless Steel Bezel
ATHS-30-12-C Tachometer/Hourmeter w/ SAE Black Bezel
Alternator Signal Tachometer 3 - 27 pulses 12 VDC
137Hz to 1330 Hz@3000 RPM
ATA-30-12 Tachometer w/ Bright Stainless Steel Bezel
ATA-30-12-A Tachometer w/ Black Stainless Steel Bezel
ATA-30-12-B Tachometer w/ SAE Bright Stainless Steel Bezel
ATA-30-12-C Tachometer w/ SAE Black Stainless Steel Bezel
ATHA-30-12 Tachometer/Hourmeter w/ Bright Stainless Steel Bezel
ATHA-30-12-A Tachometer/Hourmeter w/ Black Stainless Steel Bezel
ATHA-30-12-B Tachometer/Hourmeter w/ SAE Bright Stainless Steel Bezel
ATHA-30-12-C Tachometer/Hourmeter w/ SAE Black Stainless Steel Bezel
ATHA-40-12-A Tachometer/Hourmeter w/ Black Stainless Steel Bezel
193Hz to 1815 Hz@4000 RPM
ATVC12/24 24 VDC to 12 VDC Converter
00-00-4617 12 VDC Light Bulb
00-00-4618 24 VDC Light Bulb
GENERAL INFORMATION
Please read the following instructions before installing. A visual inspection is recommended before mounting.
General Information and these installation instructions are intended for all Tachometer and Tachometer/Hourmeter models.
Mount these units in a place where they will be protected from rain and splashing
water. A minimum distance of 12 in. (305 mm) from any coil, coil leads, or high volt-
age wiring should be maintained. These units are intended for mounting in a flat
panel. Cut a 3-3/8 in. (86 mm) diameter hole as shown below. Remove the mounting
bracket from the back of the unit. Insert the instrument from the front side of the
panel and replace the mounting bracket to secure the instrument in place.
Case Mounting Instructions
3-53/64 in.
(97 mm)
3-5/8 in.
(92 mm)
21/32 in.
(17 mm)
3-3/8 in. min.
(86 mm)
Mounting Hole
RPM
x 100
HOURS
1
10
BEFORE BEGINNING INSTALLATION OF THIS MURPHY PRODUCT
✔ Disconnect all electrical power to the machine.
✔ Make sure the machine cannot operate during installation.
✔ Follow all safety warnings of the machine manufacturer.
✔ Read and follow all installation instructions.
Front View
Side
View
Mounting Bracket
Mounting Hole
FWMurphy offers a selection of Magnetic
Sensors (pickups). For installation instruc-
tions see document MP-8802N.
WARNING
CAUTION:
Disconnect the battery/power source and determine voltage and polarity of the application
before wiring the unit. Use the appropriate wire size. To wire the magnetic sensor pickup use 18 AWG (1.0 mm
2
)
twisted pair cable. Use insulated crimp-on (solderless) ring-type wire terminals. Allow a few inches of excess
wire to make adjustments.
TAH-97029N page 2of 4
Connecting or Replacing Light Bulb
1.
Twist the “light assembly” socket one-eighth turn counterclockwise and remove
the “light assembly”. See Fig. 2 at right.
2.
To replace the bulb, pull the bulb from the socket and replace with an 00-00-4617
(for 12V), 00-00-4618 (for 24V) bulb or equivalent size as marked on the bulb.
3.
Connect the lamp blade connector to (+) positive side of instrument lighting circuit.
Connecting to Magnetic Sensor (see Fig. 2)
The magnetic sensor (pickup) usually has two connections (terminals or wires) exiting from it. These connections are not polarized, either connection can be considered
(+) positive or (-) negative signal. These two connections must be routed directly to
the unit. Do NOT ground one of the connections at the engine.
1.
Connect one of the wires in the twisted pair (from magnetic sensor) to “SIG”.
2.
Connect the other the wire in the twisted pair (from the magnetic sensor) to “GND”.
Connecting to Power (see Fig. 2)
Important: These units are for 12 VDC only.
1.
Connect a wire from “BAT” to a 12 VDC circuit activated by the ignition switch.
2.
Connect a wire from “GND” to negative voltage source (electrical ground).
Connecting ATVC12/24 Convertor (see Fig. 3)
For 24 VDC applications, a ATVC12/24 convertor must be used.
1.
Insert the ATVC12/24 convertor as shown in Fig. 3, at right.
2.
Secure the ATVC12/24 convertor with a nut on the “BAT” and “GND”stud terminals of the Tachometer.
3.
Notice that the stud terminal on the ATVC12/24 convertor becomes the “BAT”
stud for connecting to 24 VDC. Proceed with the connection as shown.
4.
Replace the 12 V bulb with the 24 V bulb supplied with the converter assembly.
Mounting Requirements
ATS and ATHS Series Models Typical Wiring
SIG
GND
BA
T
TO GROUND (-)
MOUNTING
BRACKET
TO 24 VDC
ATVC12/24
CONVERTER
Fig. 2
Fig. 3
NOTE
UD
UT
R
R
UT
R
R
UD
UD
SE
P
(
:
)
(
:
)
C
P
d
e
d
Y
CAUTION
Devices containing solid state components can be damaged or caused to
malfunction when used in systems which incorporate inductive loads (e.g.
relays, solenoids, etc.) that can generate reverse voltage spikes.
To reduce the potential for this type of damage, install a properly sized flyback or clamping diode across all inductive loads.
Shown at right is a typical example:
A typical diode is 1N4005 which is readily available from commercial
sources. Failures of this type are not covered by our Limited Warranty.
Fig. 1
Fig. 1A
RECOMMENDED TORQUE
5 TO 7 INCH POUNDS
2 PLACES ONL
LOCK WASHE
FLAT WASHE
'GND' ST
'BAT' ST
N
'SIG' ST
DO NOT TIGHTEN THE
NUTS AGAINST CLAM
N
LOCK WASHE
FLAT WASHE
RECOMMENDED TORQUE
5 TO 7 INCH POUNDS
LAM
WHEN USING ATVC12/24
24-Volt convertor car
Make Sure Nuts Ar
evel Under Car
Coil
Band
CAUTION:
TO 12 VDC ONLY
GND
BAT
SIG
LIGHT
ASSEMBLY
TO LIGHT (+) CIRCUIT
TO MAG.
PICK UP
TO GROUND (-)
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