A & A Scales PT300, Руководство по обслуживанию

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PT300, Service Manual
Rev B, October, 2000
27
Procedures
Please see Parts section for the parts drawing.
Loading pads & blocks.
At several points in the following procedures you will be asked to use loading blocks.
The tip of a test press may exert 20000 pounds of force. While PT300 scales are
designed to accept this force, they may not tolerate this on a single point. You must
use a block to distribute the force over the load surface. In general, the force should be
applied over much the same pattern as a truck tire. We suggest a 8" x 8" x 2
±
.25”
block of aluminum on top of an 8" x 8" x 0.5" piece of rubber.
Calibrate span
Tools required
Twenty thousand pound calibration press.
8" x 8" x 2
±
.25” aluminum loading block.
8" x 8" x 0.5" rubber loading pad.
Static dissipation station.
#2 Phillips screwdriver for bezel and board mounts.
Small slotted blade screwdriver.
Torque-seal potentiometer shaft sealer.
Caution:
The following procedure must only be performed at a static controlled workstation. The
main printed circuit board is subject to damage by electrostatic discharge.
Calibration
1) Remove all 10 bezel screws.
2) Detach keyboard assembly and set aside. Do not unplug keyboard.
3) Turn scale ON.
4) Wait for scale to warm up.
5) Zero the scale.
6) Apply a 10000 Lb load using loading block and pad centered on scale.
7) Adjust the span potentiometer as needed to show 10000 on the display.
(clockwise to increase, CCW to decrease) If you run out of potentiometer
travel please refer to appendix A (section titled “Selecting Initial Span Range”)
to change the span resistor.
8) Tap the span potentiometer to seat wiper.
9) Remove the test weight.
10) Repeat steps 5 to 9 until unit shows 10000.