Murphy ATS-30-12-A, ATHS-30-12, ATS-30-12-C, ATHS-30-12-A, ATS-30-12-B Installation Instructions Manual

TAH-97029N (0258) page 1 of 5

Tachometer and Tach/Hourmeter Installation Instructions

Series: ATS, ATHS, ATA, ATHA, ATHI

TAH-97029N

Revised 08-07

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.
Alternator driven models 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 are
obtained from the ring gear of an engine’s flywheel (having from 70 to 225 teeth) using
an electromagnetic sensor (pickup).

Ignition signal driven models available for 4, 6 and 8 cylinder, spark ignited engines.

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, an optional
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.

Models

Magnetic Sensor Tachometer 3000 RPM; 70 - 225 pulses 12 VDC

Model # Designation

ATS-30-12 Bright Stainless Steel Bezel
ATS-30-12-A Black Stainless Steel Bezel
ATS-30-12-B SAE Bright Stainless Steel Bezel
ATS-30-12-C SAE Black Stainless Steel Bezel

Magnetic Sensor Tach/Hourmeter 3000 RPM; 70 - 225 pulses 12 VDC

ATHS-30-12 Bright Stainless Steel Bezel
ATHS-30-12-A Black Stainless Steel Bezel
ATHS-30-12-B SAE Bright Stainless Steel Bezel
ATHS-30-12-C SAE Black Stainless Steel Bezel

Alternator Signal Tachometer 3000 RPM; 3 - 27 pulses 12 VDC

ATA-30-12 Bright Stainless Steel Bezel
ATA-30-12-A Black Stainless Steel Bezel
ATA-30-12-B SAE Bright Stainless Steel Bezel
ATA-30-12-C SAE Black Stainless Steel Bezel

Alternator Signal Tach/Hourmeter 4000 RPM; 3 - 27 pulses 12 VDC

ATHA-30-12 Bright Stainless Steel Bezel
ATHA-30-12-A Black Stainless Steel Bezel
ATHA-30-12-B SAE Bright Stainless Steel Bezel
ATHA-30-12-C SAE Black Stainless Steel Bezel

ATHA-40-12-A Black Stainless Steel Bezel

Ignition Signal Tach/Hourmeter 4000 RPM; 4, 6 or 8 cylinder 12 VDC
ATHI-40-12-A Black Stainless Steel Bezel

Optional Items and Replacement Bulbs
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

For a selection of Magnetic Sensors (pickups) see

installation instructions document MP-8802N.

WARNING

TAH-97029N (0258) page 2 of 5

CCAAUUTTIIOONN::

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.

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

BAT

TO GROUND (-)

MOUNTING

BRACKET

TO 24 VDC

ATVC12/24

CONVERTER

FFiigg.. 22

FFiigg.. 33

NNOOTTEE

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.

FFiigg.. 11

FFiigg.. 11AA

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 (-)