OPTIC CABLES
These head duty cables are used to connect the transmitter / receiver to the wireless sensor head black
box module. The cables are keyed so they cannot be connected incorrectly
Sensor Head Black Box Module
The sensor head module is a sealed unit and no maintenance is required for the operation of the meter.
Ensure the battery is fully charged as indicated by the Led on the charging unit.
Zero Drift
The zero drift is a procedure to ensure that lenses are not being soiled during a test. Prior to the
preliminary snaps, the meter measures zero opacity. At the end of the three final snaps, the meter
directs the user to turn the engine off and remove the sensor from the stack. NOTE: if you only turn off
the engine and do not remove the sensor from the stack, there are still hot gases rising. So you may fail
the zero drift. So after you have turned off the engine and removed the sensor from the stack, the meter
measures zero opacity again. Now the meter will compare the initial zero to the ending zero. To pass
the zero drift procedure, the difference between the initial zero and the ending zero cannot be greater
than 2% opacity. If you are continuously failing the zero drift, there are certain steps to determine the
cause.
First, run a simulated test. Leave the sensor head on a table or bench and run a snap acceleration test
without the sensor head on the vehicle. All preliminary snaps, all final snaps, and the zero drift should
be zero or close to zero. If any of the readings are greater than 2%, this indicates something is
defective and contact your vendor. If all the readings are zero or close to zero, this indicates that the
meter is working properly and the most likely reason you are failing the zero drift is that the lenses are
being coated by soot. In this case, clean the lenses before you start the test and also a second time at
the point where it says “turn off the engine and remove the sensor from the stack”. So turn off the
engine, remove the sensor from the stack, unclip the optics one at a time, clean the lenses, re-attaching
both optics, and then press enter to perform the zero drift test.
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Invalid Test
The number one cause for an invalid test is the spread. The spread is the difference in the highest
reading and the lowest reading and cannot exceed 5% opacity. For example, on the preliminary snap
readings of 24%, 18%, 12%, the spread will be 24-12=12%. So this will be an invalid test as the spread
is greater than 5%. To eliminate this spread failure, ensure the vehicle is at normal operating
temperature, and perform a few blowout snaps prior to performing the inspection test, then attach the
head and perform the test.
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