OHAUS Valor 1000W Service Manual

CHAPTER 2 DIAGNOSTIC GUIDEValor™ 1000W Series Service Manual 2-3 Ohaus Corporation www.ohaus.com2.2.2 Checking Load Cells for TroubleFigure 2-1. Load Cell wire connections to Main PCB.CAUTION:IN THE NEXT STEP, DO NOT OVERLOAD THE SCALE BEYOND FULLCAPACITY RATING.– Measure the voltages on IN- and IN+ wires, disconnected from PCB(points 1 and 2 in Figure 2-1). Note: Measurements must be made with thesewires disconnected from the PCB. These measurements represent the output ofthe Load Cell. Record measurements at Zero Load, 50% and full scalecapacities. See Table 2-3 for typical readings.NOTE: Table 2-3 indicates typical readings. Actual values can vary, but shouldremain linear throughout the range. If readings are out of tolerance, replace theLoad cell. (See Section 3.6.)TABLE 2-3. LOAD CELL OUTPUT READINGS (in mV with 5V Excitation)Model/Capacity Zero Load 50% Load 100% LoadV11PW3 / 3kg 1.5 ± 2.0 Zero + 4.1 Zero + 6.7V11PW6 / 6kg 0.9 ± 2.0 Zero + 3.4 Zero + 5.9V11PW15 / 15kg 0.6 ± 2.0 Zero ± 3.2 Zero ± 5.9V11PW30 / 30kg 0.3 ± 2.0 Zero + 2.8 Zero + 5.4