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 17 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 FD 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 9 V dcat 500mA. 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 17 V dc.2. Perform procedure Section 4.1 and remove Top Housing. Plug the AC Adapter into the scale andmeasure the test points for the AC connector, see Figure 3-2. The output voltage should be 9Volts dc minimum, and 14 Volts dc maximum. If the voltage is below or above these readings,replace the Adapter.3.2 TESTING THE MEMBRANE SWITCHThe Membrane switch can be tested after removing the Top Housing from the Base Housing.1. Refer to Section 4.1 and remove the Top Housing.2. Refer to Figure 3-1. Using an Ohmmeter, measure the resistance between pin 5 to all other pinson the membrane switch cable, the readings should be infinite resistance. Then, press each buttonand check that the resistance is zero for each button. If continuity is not present, the membraneswitch is defective. Replace the Membrane Switch.3. Check that the Membrane Switch is not shorted to the Top Housing case. Check pins 1 through5 to the case which should be infinite resistance.4. Reassemble Top Housing to Base Housing.Figure 3-1. FD Series Scales Membrane Switch Wiring Diagram.