General Technologies TA303 SmarTach : Diesel & Gasoline Engine Tachometer - Manual (Page 2)

4.4 Introduction to the TA303
The rectified output of an alternator consists of a DC voltage (or
current) and “ripples”, which are the result of successive sine
waves generated by each of the alternator’s fields being added to
one another, slightly out of phase with each other.
The alternator is connected to the engine crankshaft, usually through
a drive belt, so the number of ripples generated by the alternator
is proportional to the speed of the engine, with a different ratio of
ripples to RPM for each particular engine/alternator combination.
The TA303 uses a proprietary calibration procedure to automatically
calculates the alternator ripple-to-RPM ratio, which is then used to
measure the engine’s RPM.
4.5 Measurement Procedures
4.5.1 Connecting the TA303
!
Caution
Do not connect the TA303 or it cables to any voltage
above 42 VDC or to AC power. Exceeding this limit
can expose you to physical injury and permanently
damage your instrument and components of the
unit under test.
There are two adapter cables provided with the TA303: one with
battery clips for direct connection to the battery terminals, or another
suitable location, and a second cable for connecting to a standard
cigarette lighter socket. An extension cable is also provided, in
case the TA303 is to be positioned farther from the connection than
is possible with the regular cables.
Using the battery cable
•
Connect the BNC plug connector of the battery cable to the BNC
jack connector provided in the TA303. If using the extension
cable, first connect the BNC plug of the battery cable to the BNC
jack of the extension cable and then connect the BNC plug of the
extension cable to the BNC jack of the TA303.
• Connect the black alligator clip of the battery cable to the
negative terminal post of the battery, or other suitable ground,
then connect the red alligator clip to the positive battery post or
other suitable positive power connector.
Using the cigarette lighter connector
• Connect the BNC plug connector of the cigarette lighter
connector to the BNC jack connector provided in the TA303.
If using the extension cable, first connect the BNC plug of the
cigarette lighter adapter to the BNC jack of the extension cable
and then connect the BNC plug of the extension cable to the BNC
jack of the TA303.
• Insert the cigarette lighter adapter into the cigarette lighter socket
of the vehicle, and observe if a red LED light turns on in the
adapter, indicating that it is powered.
Note: In some vehicles the cigarette lighter socket is connected to
the battery through electronic circuits or special filters which
may interfere with the signal the TA303 uses to measure
RPM, which may produce unreliable readings.
4.5.2 Setting the number of cylinders
• Each time the cylinder increase button is pressed, the
number of cylinders will be increased, and the selected
number of cylinders will be shown on the display.
• Each time the cylinder decrease button is pressed, the
number of cylinders will be decreased, and the selected
number of cylinders will be shown on the display.
Note: The selected number of cylinders can be changed at any
time during a measurement, if necessary.
4.5.3 Setting the number of cycles
Engine
Cycles
2 - 4
• Press the engine cycles button to select the number of
cycles for the engine under measurement. Each time the
button is pressed the number of cycles will change
between 2 and 4 cycles. The selected setting will show on
the display.
Note: The selected number of cycles can be changed at any time
during a measurement, if necessary.
4.5.4 Calibrating the TA303
The TA303 needs to be calibrated for each engine before it can
measure. During calibration, the TA303 performs a series of
measurements and mathematical operations to calculate the ratio
of alternator ripples to RPM, which it will later use to measure
engine RPM.
For proper and accurate calibration, the following procedure should
be followed:
• The engine must be running at a stable idle speed. Wait at least
one minute after the engine has started before pressing the
calibrate button.
• Turn off all accessories attached to the engine or electrical
system (e.g.: air conditioning, windshield wipers, stereo, etc.), to
avoid introducing mechanical and / or electrical noise which may
affect the TA303.
• Turn on the vehicle’s headlights (high beam is preferable), in
order to create an electrical load, which makes the alternator
ripples more stable and easier to detect.
Calibrate • Press the calibrate button to initiate calibration of the
TA303 to the engine being measured. During calibration,
which takes a few seconds, the TA303 will flash ‘CAL’ on
it display.
• Once the calibration is finished, the display will automatically
start to show RPM readings.
Note: The selected number of cycles can be changed at any time
during a measurement, if necessary.
4.5.5 AUX Button
• The AUX button is reserved for factory use.
5. MAINTENANCE
Keep the instrument in its carrying case when not in use and do
not subject it to dampness, severe heat, or cold. Do not use the
instrument in the rain, if it should get wet, dry it off with a clean
paper towel before storing it.
Protect the unit from contact with any solvents. Never clean with
a solvent or petroleum based medium such as gasoline, as these
chemicals may attack the plastic parts and cause permanent
damage. Never use an abrasive cleaner. Cleaning should be
limited to wiping with a clean damp paper towel and a small amount
of soap if required. Dry the unit thoroughly after any cleaning.
The unit is a sealed instrument, contains no user serviceable parts.
Any non factory authorised service personnel opening the unit will
void the warranty.
6. WARRANTY
This instrument is warrantied against defects of parts and
workmanship which develop within a period of one (1) year
following the date of purchase by the original owner. For details
see Standard Warranty Information on our web page at www.gtc.ca
or you may request a printed copy.
© Copyright 2013 General Technologies
General Technologies Corp.
#121 - 7350 72nd Street Tel.: (604) 952-6699
Delta, BC Fax: (604) 952-6690
Canada V4G 1H9 www.gtc.ca