OPERATING INSTRUCTIONS MODEL DT-33K3
KEYBOARD CONFIGURATION
P O W E R
P O W E R
ON
ON
DIGATRON MODEL DT-33
EGT
CHT
TACH
M O D E
M O D E
R E C A L L
R E C A L L
R E C A L L
R E C A L L
M A X I M U M
M A X I M U M M E M O R Y
M E M O R Y
S T O R E
S T O R E
POWER OFF
SET LIMITS
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-33K3, 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.
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
kart’s engine turned off. Press and hold the
MAXIMUM
RECALL
and
MEMORY RECALL
buttons simultaneously
until the bottom display flashes. This will put the instrument
into the Set Limits mode of operation, which is indicated by a
flashing display. 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 first limit, press the
MODE
button to set the next limit. Repeat the above procedure to set
the remaining limits. Set limits at levels high enough for normal
operation, but not so high that engine damage can occur before
you can respond to a problem.
The tach limit requires the setting of two separate parameters.
The first is the maximum RPM for safe engine operation. The
second number is for tach calibration. In order 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.
The most frequently used numbers are:
.5 - for some single cylinder 4 cycle motors
1 - for single cylinder 2 cycle and some 4 cycle motors
2 - for 2 cylinder 2 cycle and 4 cylinder 4 cycle motors
If you are unsure of the exact tach calibration number for your
engine, experiment. If your calibration number is currently set at
1 and the RPM displayed is double what it should be, set the
calibration number to 2. 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
switch.
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.
CYLINDER HEAD TEMPERATURE
Cylinder head temperatures (CHT) usually run in the 300
º
F to
475
º
F range. The best way to determine the correct temperature
for your particular motor is to tune for proper plug or piston
color and then observe what the head temperature is for
various throttle settings and atmospheric conditions.
Temperatures of 450
º
F or over will damage the standard CHT
sensor. If your motor frequently runs at cylinder head
temperatures over 450
º
F your instrument should have an
exhaust gas temperature function, which can use a
thermocouple CHT sensor. This sensor can be used without
damage at higher temperatures, but it is not as accurate as our
standard CHT sensor.
TACHOMETER
The tach displays RPM in thousands of RPM.
For example, if your display shows 9.50, your RPM is 9500
RPM.
