TM 5-3895-374-24-2
4.
Verify the asphalt density for the current mix formula as shown on screen 2 is non zero and correct for the material
in use.
5.
Verify that the asphalt temperature is approximately correct.
6.
Measure the dc component for the asphalt meter pulse output on the Blend I/O asphalt meter terminal strip
terminal 22 (+) and terminal 21 (-).
7.
If the measured voltage is 0 go to PROCEDURE 3, Blending Control fails to respond.
8.
If the measured voltage is greater than 20 vdc, or less than 1 vdc, replace the three wire asphalt rate pickup probe
in the Asphalt Meter J-box. The asphalt meter calibration may not change if the correct replacement is properly
installed. Replace the pickup wheel if its rubber outer ring shows any signs of physical damage.
Asphalt Meter Rate - Erratic Rate Indication
NOTE
Meter re-calibration may be required if components are replaced.
Inspect all sensor cables and connections.
1.
Verify asphalt temperature. Verify the meter shaft is actually turning, and that the casting at the outboard bearing
of the meter has not been broken by excessive line pressure.
2.
Stop the asphalt flow and open the Asphalt Meter J-Box and verify that the pulse pickup wheel is mechanically
centred on the pickup probe and secured to the meter output shaft. Measure the pickup probe gap to the sensor
wheel. The pickup should not contact he wheel and the gap should be less than 0.040 inches. Restart the asphalt
flow. 0
3.
Replace the frequency input buffer module in line with Blend I/O terminals 21- 22.
Asphalt Pump Speed Control
Inspect all sensor cables and connections.
1.
Verify this drive operated properly in the manual position (feeder panel).
2.
Verify a suitable value for the Maximum A/C rate as shown in screen 865 in TPH. The value used should be 2 to 4
times greater than the actual maximum pump output.
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