Digatron DT-31SN2 Operating Instructions

OPERATING INSTRUCTIONS MODEL DT-31SN2
KEYBOARD CONFIGURATION
DIGATRON MODEL DT-31
TACH / EGT
POWER
MODE
ON
POWER ON
When turned on, your instrument will begin a 10 second
display test. At the end of the test, your instrument's serial
number will be displayed. To bypass this test press the MODE
button.
SETTING FUNCTION LIMITS
Before using your DT-31SN2, be sure to set the operating limits
for each sensor. The instrument will not allow limits to be set
while the engine is running. This is to prevent possible
damage to your instrument. Usually the instrument will turn on
without turning your engine on.
Limits allow the instrument to give you a visual warning if any
of the inputs exceed their limit. Limits should be set at levels
that allow you to react to the visual warning before engine
damage occurs. You will also need to set a calibration number
so the instrument can display the correct RPM.
To set the limits, the instrument must be turned on and the
sled's engine turned off. Press and hold the MAXIMUM
RECALL and MEMORY RECALL buttons simultaneously
until the display flashes. This will put the instrument into the
Set Limits mode of operation, which is indicated by the display
flashing. To increase the limit, press the MAXIMUM RECALL
button. To decrease the limit, press the MEMORY RECALL
button. To increase or decrease the limit by a large amount,
press and hold either the MAXIMUM RECALL or the
MEMORY RECALL button until the approximate limit value is
reached. When finished setting the tach limit, press the MODE
button to go to the next value, which is the tach calibration
number.
The tach calibration number enables the instrument to display
the correct RPM for different engine types. The instrument
divides the tach input signal by the tach calibration number.
This number can be between .5 and 31. Select this number so
that it will provide the correct display for your application
using the MAXIMUM RECALL and MEMORY RECALL
buttons.
Find the correct tach calibration number for your sled by
determining how many poles your lighting coil has and divide
this number by two. This is your tach calibration number.
MAXIMUM MEMORY STORE
RECALL RECALL CLEAR
SET LIMITS POWER OFF
The most frequently used numbers are:
2 cylinders - set at 2 or 4
3 cylinders - set at 3 or 6
4 cylinders - set at 4 or 6
If you are unsure of the exact tach calibration number for your
engine, experiment. If your calibration number is currently set at
2 and the RPM displayed is double what it should be, set the
calibration number to 4. Alternately, if the RPM displayed is
half of the correct value, decrease the calibration number to half
of the current number.
To save the current limits and exit the Set Limits mode, press
the STORE button or switch.
TACHOMETER
The tach displays RPM in thousands of RPM. For example, if
your display shows 9.50, your RPM is 9500 RPM.
EXHAUST GAS TEMPERATURE
Exhaust gas temperature (EGT) is used primarily for adjusting
the air/fuel ratio. Because of its quick response, the effects of
carburetor adjustments are seen immediately. Fuel system and
carburetor problems can often be spotted quickly enough to
prevent engine damage.
Exhaust gas temperatures typically run between 1100°F and
1350°F. The EGT on a properly tuned engine will increase
rapidly as the throttle is opened and as the load on the engine
is increased. At full throttle and full load the EGT will stabilize
at a temperature dependent on the air/fuel ratio. Both a "too
lean" or a "too rich" condition will be indicated by a lower than
peak temperature. The "too lean" condition can damage your
engine. An increase in coolant temperature or cylinder head
temperature is usually an indication of this. The best way to
determine what temperature is normal for your motor is to tune
for good plug or piston color and then observe the temperature
at various throttle settings.
MODE BUTTON
During operation, the MODE button is used to change from the
primary to the secondary function in the top display. When the
instrument is first turned on, the primary function (tach) is
displayed. The secondary function (EGT) operates in the
background until the MODE button is pressed or until it's limit
is exceeded.
STORING DATA
The STORE switch or the optional REMOTE STORE switch
can be pressed up to three different times to store the current
values of each function into memory. The display and the
optional WARNING INDICATOR LIGHT will flash to indicate
a successful store of information. After three numbers are
stored, additional attempts to store information will be ignored.
In addition, the instrument automatically stores a maximum tach
value during the current recording period.