Service Manual RU OHAUS
Page 21 / 53 11/01/2010 Ohaus
9. Load Cell
The Load Cell can be tested for proper analogue voltage input and millivolt output by
measuring the voltage on the Main Logic PCB. To check the input voltage across
+EXC & -EXC, place your meter on volts and put the positive lead on the left pin of F1
and the negative lead on the left pin of F4. You should be reading a steady +10VDC +/-
0.25VDC.
If the Excitation voltage is good, the signal output can be checked across +SIG & -SIG.
Set the meter to read in millivolts (mV). Put the positive lead on the left pin of F2 and
negative lead on the left pin of F3. With no weight on the platter, you should read zero
data. As you add weight to the platter, the voltage should rise and be linear if equal
weight is added each time. If the output is linear and correct, but no weight is displayed,
replace the Main Logic PCB. If there is no output from the load cell, but correct input
voltage, replace the load cell.
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