TM 5-3895-359-14&P
FIGURE 8
On the back of the V.P.I. panel, disconnect leads #3
and #8 (from the meter) and leads #1 and #3 (from the
tach wheel) at the terminal block.
Consult the application reference chart for both a
gallons per minute indicator reading and a feet per
minute indicator reading that will correspond to the
application rate selected.
Feed in from one adjustable external voltage source to
positions #3 and #8 (for the meter) and from another
adjustable external voltage source to positions #1 and
#3 (for the tach wheel) on the terminal block. These
voltage sources should have a variable range from .5
volts D.C. to 2 volts D.C. When the proper voltages
have been introduced to obtain the respective meter
reading indicated on the application reference chart for
the rate previously selected, the performance meter
should read zero ("0") and be in a vertical position. If it
does not, adjust the performance meter balance
potentiometer on the back of the V.P.I. panel to a
position where the performance meter does read zero
("0"). This calibration should be checked by selecting a
different application rate, changing the meter readings
by varying the voltages to the corresponding application
reference chart readings and again check the
performance meter for a zero ("0") reading. If the
performance meter zero ("O") readings are not
consistent, check the fixed resistors in the V.P.I. circuit.
Remove the external voltage leads from the terminal
block positions #1 and #3, and #3 and #8 and re-attach
the tach-generator leads to their respective positions on
the terminal block. Place a drop or two of nail polish on
FIGURE 9
the shafts of any of the potentiometers on the back of
the V.P.I. that have been re-adjusted prior to bolting the
V.P.I. panel back in its operating position.
The total V.P.I. system is now adjusted and ready for
use.
13-5
