Testing The Printed Circuit Board (Pcb) - OHAUS Valor 2000 Service Manual

CHAPTER 2 DIAGNOSTIC GUIDE

2.2.3 Testing the Printed Circuit Board (PCB)

The PCB can be tested by measuring voltages and by using a simulator. The simulator
replaces the Load Cell during testing and is a useful tool for diagnosing problems.
PCB Voltage Measurements
Note: Prior to the voltage measurements, the battery should be fully charged and tested.
1. Disconnect power from the scale, and remove the Top housing. (See Section 3.3.1.)
2. Connect the AC Adapter to the scale and turn the scale on.
3. Using a DVM, measure the excitation voltage (EXE+ and EXE– in Figure 2-1.)
The reading should be 5 volts dc. This is the excitation voltage for the Load Cell
and is regulated. If the voltage is lower, replace the PCB. (See Section 3.4.)
Then perform Operational Tests. (See Chapter 4.)
4. Measure incoming power from the AC Adapter Connector shown in Figure 2-1. The
voltage should read between 9 and 14 volts dc with power off and above 9 Volts dc
with power on.
5. Perform simulator testing.
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