Load Cell Wire Color Identification; Replacing The Load Cell - OHAUS NV212 Service Manual

3.3 REPLACING THE LOAD CELL

The Load Cell may need to be replaced because of scale instability, or because the scale does not
calibrate or repeat, or because it is physically broken or displays an error code.
Disassembly:
1. Open the scale – see Section 3.2. Verify that there is no mechanical interference, pinched wire
or bad solder connection that may be causing the load cell to appear defective.
2. Remove the Load Cell – turn the scale over, holding the Load Cell by hand, and remove the 2
load cell screws from the bottom housing. The NV model uses cross-recess screw heads (Phillips
type) while the NVL and NVT use hex socket head screws.
3. Turn the scale back on its feet and gently lift off the Load Cell, the attached PCB and the AC
Adapter cable. Place the Load cell and the PCB on a static protected work area.
4. The load cell connection is a five-wire cable that is soldered directly to the PCB. Before
disconnecting the cable record the wire colors and their location on the PCB. (Hint: A digital picture
is an easy and reliable record.) Disconnect the cable connecting the PCB to the Load Cell by un-
soldering the 5 wires from the PCB. Take care not to over heat the PCB which will damage the thin
PCB conductors.
Re-Assembly:
1. Re-solder the new load cell to the PCB, connection J3.
NOTE: The spare part Load Cell may not have the same wire color identifications as the original
load cell. It is necessary to identify the wires from the table below.
J3 has 5 solder pads with the following connections (left to right); Shield, -EXE, -SIG, +SIG, +EXE.
Spare Part Load Cell
Load cell,NV212
Load cell,NV311
Load cell,NV511,NV1101,NV2101
Load cell,NV3100
Load cell,NV4101,NV5101
Load cell,NVL20000
Loadcell,NVT1601,NVL511,NVL1101,NVL2101
Loadcell,NVT3200
Loadcell,NVT6400,NVL5101
Loadcell,NVT10000,NVT16000,NVL10000
Navigator Series Service Manual
TABLE 3-1. Load Cell Wire Color Identification
21
CHAPTER 3 MAINTENANCE PROCEDURES
Wire Color Identification
Shield Bare wire with sleeve
-EXE Black wire
-SIG White wire
+SIG Red wire
+EXE Green wire
Shield Bare wire with black sleeve
-EXE Black wire
-SIG Red wire
+SIG White wire
+EXE Green wire
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