OHAUS FD SERIES Service Manual

Also see for FD Series: Instruction manual User guide Quick start guide

Contents

OHAUS FD SERIES Service Manual Manual pdf 21 page image

3-5CHAPTER 3 SCALE TESTING AND CALIBRATION3.4.2 Simulator TestingTo perform these tests, the use of a Simulator is required. The basic function of a Simulator is to simulatethe output of a full bridge Load Cell allowing the scale to be separated from the Load Cell for the purposesof troubleshooting and calibration. The Load Cell used in the scale is rated at 2mV/V output with a 5 Voltexcitation voltage applied.General Load TestThis test checks the Main PC Board circuitry by simulating accurate load cell voltages at 0%, 50% and100% load capacities.1. Disconnect power from the scale.2. Remove the Top housing, refer to Section 4.1 and leave the Membrane Switch connected to thescale.3. Disconnect the battery.4. Disconnect the Load Cell cable from connector J1 on the main PC Board. Refer to Figure 3-2 forlocation.5. With the Simulator set to zero, connect the Simulator to connector J1 using Alligator clips.6. Connect a known good AC Adapter to the scale and connect to a power source.7. Turn on the scale, CLEAR PAN, ERROR 14 should be displayed. This is normal.8. Set the scale to indicate weight in kilograms (kg) and set the calibration value to maximum spanvalue.9. Review Table 3-2 and adjust the Simulator to simulate 0% load, 50% load and 100% load for thecapacity that the scale is rated for. If the resulting readings are unstable, the Main PC Board isdefective. Use the Simulator to calibrate the scale in the next procedure to verify if the Main PC Boardis good or bad.Calibration TestThis test calibrates the scale using the simulator and can verify that the Main PC Board is functioningproperly or improperly.1. With the scale on and the Membrane Switch connected, enter the scale menu and perform a spancalibration according to the Instruction Manual.2. Follow the scale prompts. When the scale indicates a given weight should be placed on the scale,set the simulator to an equivalent value based on Table 3-2. For example, when a span value of6 kg for a 6 kg scale is shown, the simulator should be set to .8 mV/V.