OHAUS EC SERIES Service Manual

Also see for EC Series: Instruction manual Instruction manual

Contents

OHAUS EC SERIES Service Manual Manual pdf 18 page image

3-4CHAPTER 3 SCALE TESTING AND CALIBRATION3.4 TESTING THE MAIN PC BOARDThe Main PC Board can be tested by measuring voltages and by using a simulator. The simulator replacesthe Load Cell during testing and is a useful tool for diagnosing problems.3.4.1 Main PC Board Voltage MeasurementsPrior to making the voltage measurements, the battery should have been fully charged and tested.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 from the Main PC Board.4. Remove screws and washers holding the Main PC Board and lift the board and lay flat.5. Connect the AC Adapter to the scale.6. Refer to Figure 3-2, Interconnection Diagram which illustrates the interconnections to the Main PCBoard and is shown as a top view.7. Turn the scale on.8. Using a DVM, measure the excitation voltage across +EXE and -EXE leads it should be 5 volts dc.This is the excitation voltage for the Load Cell and is regulated. If the voltage is lower, replace theMain PC Board, refer to Section 4.3 and then proceed with Performance Tests in accordance withSection 3.6.9. Measure incoming power from the AC Adapter connector shown in Figure 3-2. The voltage shouldread above 6 Volts dc with power on.10. Connect the battery to the Main PC Board and measure the voltage across Black and Red leads onthe battery connector. The full battery voltage should read a minimum of 6.0 Volts dc. If the voltageis lower, the battery may require charging or it may be defective. Refer to section 3.5 and test thebattery.11. Perform simulator testing.