Sartorius Master Pro LA12000P, Service Manual

Page: 30 / 64

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Preload
You only need to check the preload if:
– the weighing system has been rebuilt (i.e., if the linkage was replaced)
– the weighing system was damaged
– the user wishes to change the preload (e.g., to use a special weighing
pan) while retaining the entire weighing range
Note: There are restrictions on the extent to which the preload can be changed!
In general, an increase in the preload by more than 10% is not permissible.
If necessary, contact the International Service Support or Customer Support
in Goettingen.
There are 2 different ways to check/adjust the preload:
– With the service software (SARTOCAS program or PSION Server)
– With a digital voltmeter
Checking the Preload
Note: If the preload values have changed significantly, this indicates a mechanical
or electronic error.
1. Checking the Preload with the Service Software
– Replace the pan flexures and weighing pan on the balance, connect the
power supply and turn on the balance.
– Activate the BPI mode (see page 10).
– Connect the PSION Server or a PC/laptop with the SARTOCAS program.
– Start the service software and save the data records that are currently in the
balance.
– Select the ELECTR.ZERO item from the DIAGNOSTICS submenu.
– Place the required preload test weight on the balance (see “Adjustment
Specifications,” page 31) and read the PSION server/PC display.
– Compare the value displayed to the tolerance range given in the adjust-
ment specifications.
– If the displayed value exceeds the tolerance limits, the preload must be
adjusted.
2. Adjusting the Preload with a Digital Voltmeter
– Solder 2 instrument leads to the balance PCB at positions A and B (parallel
to the measuring resistor) and connect them to the digital voltmeter.
– Replace the pan flexures and weighing pan on the balance, connect the
power supply and turn on the balance.
– Set the digital voltmeter for a range of 20 V DC and place the required
preload on the balance (see “Adjustment Specifications,” page 31).
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