OHAUS EC SERIES Service Manual

Also see for EC Series: Instruction manual Instruction manual

Contents

OHAUS EC SERIES Service Manual Manual pdf 15 page image

3-1CHAPTER 3 SCALE TESTING AND CALIBRATION3. TESTING AND CALIBRATIONThis section of the manual contains testing procedures of the individual replaceable components and thescale. Before and after servicing the EC Series Scales, an operational test and various performance testsshould be made to ascertain whether or not the scale meets specifications.3.1 TESTING THE AC ADAPTERThe AC Adapters are available with different input voltages. Before testing the Adapter, make sure theAdapter rating agrees with the power source being used. All Adapters are rated with an output of 12 V dcat 800mA. Adapters can fail by having shorted internal windings producing low voltage output or nooutput at all.1. Plug the AC Adapter in a suitable power source and measure the open circuit voltage on connectorit should be 10 V dc to 16 V dc.2. Refer to Section 4.1 and remove the Top Housing. Plug the AC Adapter into the scale andmeasure the voltage on the battery terminals. Turn the scale on. The voltage should be 6.5 Voltsdc minimum, and 7.5 Volts dc maximum. If the voltage is below or above these readings, replacethe Adapter. This is the actual battery voltage while charging.3.2 TESTING THE MEMBRANE SWITCHThe Membrane Switch can be tested after removing the Top Housing from the Bottom Housing.1. Refer to Section 4.1 and remove the Top Housing.2. Disconnect the Membrane Switch connector from the Display PCB.3. Refer to Table 3-1. Using an Ohmmeter, measure the resistance between the pins shown in thetable. The readings should be less than 70 Ohms for each button. If continuity is not present orthe resistance is higher than 100 Ohms, the Membrane Switch is defective. Replace the MembraneSwitch. Figure 3-1 illustrates the cable connector and pin locations.4. Reassemble Top Housing to Bottom Housing.TABLE 3-1. MEMBRANE SWITCH PIN CONNECTIONS.PANEL BUTTON PINSSAMPLE 8 to 3TARE 9 to 3M+ 6 to1PT 7 to 1APW 6 to 2ZERO 7 to 2• 9 to 5C 9 to 40 9 to 21 8 to 22 8 to 53 8 to 44 7 to 55 7 to 46 7 to 37 6 to 58 6 to 49 6 to 3Figure 3-1. Membrane Switch Connector.