OHAUS EB SERIES, Service Manual

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CHAPTER 2 DIAGNOSIS
Ohaus Corporation www.ohaus.com 2-6 EB Series Scales Series Service Manual
2.5. TESTING THE AC ADAPTER
The AC Adapters are available with different input voltages. Before testing the Adapter, make
sure the Adapter rating agrees with the power source being used. All Adapters are rated with an
output of 12 V dc at 800mA. Adapters can fail by having shorted internal windings producing low
voltage output or no output at all.
1. Plug the AC Adapter in a suitable power source and measure the open circuit voltage on
connector it 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
and measure the voltage on the battery terminals. Turn the scale on. The voltage should
be 6.5 Volts dc minimum, and 7.5 Volts dc maximum. If the voltage is below or above
these readings, replace the Adapter. This is the actual battery voltage while charging.
2.6 TESTING THE MEMBRANE SWITCH
The 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 the table. The readings should be less than 70 Ohms for each button. If
continuity is not present or the resistance is higher than 100 Ohms, the Membrane
Switch is defective. Replace the Membrane Switch. Figure 3-1 illustrates the cable
connector and pin locations.
4. Reassemble Top Housing to Bottom Housing.
TABLE 2-8. MEMBRANE SWITCH PIN CONNECTIONS.
PANEL BUTTON PINS
Figure 2-1. Membrane Switch Connector.
M+ 1 to 2
UNITS 1 to 3
ZERO 1 to 4
TARE 1 to 5
CHECK 1 to 6
COUNT 1 to 7
% 1 to 8