Service manual

PT300, Service Manual
Rev B, October, 2000
31
Assembly
16) Set new load cell in place.
17) Glue the load cell lead off to the side so it doesn’t run under the middle of
the load cells.
18) Thread load cell lead through hole in case.
19) Apply RTV liberally where load cell lead enters case. Work RTV compound
inside feed-through hole.
20) Replace strap assembly.
21) Replace 8 bolts holding strap assembly. Use permanent locktite (RED) and
torque bolts to 12 ft-lbs.
22) Replace platform.
23) Replace 6 bots holding platform. Use removable locktite (BLUE) and torque
bolts to 12 ft-lbs.
24) Solder load cell leads to summing board, using the same color code hookup
as the removed load cell.
25) Clean soldering flux from newly soldered leads.
26) Check and adjust load cell deadload. Please see appendix A for details.
27) Replace insulator on back of summing board.
28) Return summing board in housing.
29) Place circuit board into housing. Be careful not to pinch the wires between
the battery tube and the printed circuit board.
30) Install two board mounting screws.
31) Check and adjust the front/back load cell balance given in the following
procedure.
32) Check and adjust calibration as needed (see calibration procedure).
33) Reassemble keyboard assembly.
34) Replace bezel screws.
Check front/back load cell balance
Tools required
Twenty thousand pound calibration press.
1.5" x 1.5" x 12" aluminum loading block.
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 be performed at a static controlled workstation. The
main printed circuit board is subject to damage by electrostatic discharge.
Load cell locations used in the following procedure.