OHAUS NV212 Service Manual

Also see for Navigator NV1101: Instruction manual Instruction manual

Contents

OHAUS NV212 Service Manual Manual pdf 27 page image

CHAPTER 3 MAINTENANCE PROCEDURESNavigator Series Service Manual 21 Ohaus Corporation www.ohaus.com3.3 REPLACING THE LOAD CELLThe Load Cell may need to be replaced because of scale instability, or because the scale does notcalibrate 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 wireor 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 2load cell screws from the bottom housing. The NV model uses cross-recess screw heads (Phillipstype) 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 ACAdapter 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. Beforedisconnecting the cable record the wire colors and their location on the PCB. (Hint: A digital pictureis 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 thinPCB 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 originalload 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.TABLE 3-1. Load Cell Wire Color IdentificationSpare Part Load Cell Wire Color IdentificationLoad cell,NV212 Shield Bare wire with sleeve-EXE Black wire-SIG White wire+SIG Red wire+EXE Green wireLoad cell,NV311Load cell,NV511,NV1101,NV2101Load cell,NV3100Load cell,NV4101,NV5101Load cell,NVL20000Shield Bare wire with black sleeve-EXE Black wire-SIG Red wire+SIG White wire+EXE Green wireLoadcell,NVT1601,NVL511,NVL1101,NVL2101Loadcell,NVT3200Loadcell,NVT6400,NVL5101Loadcell,NVT10000,NVT16000,NVL10000