Service manual

PT300, Service Manual
Rev B, October, 2000
40
Appendix A
Setting the deadload.
The output signal from the load cells is set to a value slightly above zero with zero
weight applied. This is done for two reasons; one is to detect any errors in the load
cells, the other is to run the A/D converter in its most accurate operating point. The
"Deadload" or "Tare" must be set with no weight on the scale. This is not a regular
maintenance item, it should only need to be adjusted when changing a circuit board or
load cell. Please refer to the diagram below while reading the following section.
Figure 14 Summing Board
Function of JP1:
Position 1. Lower raw counts
Position 2 Raise raw counts
Position 3 Not used
Position 4 Not used
Position 5 Selects R8 (15M)
Position 6 Selects R7 (22M)
Position 7 Selects R6 (47M)
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