The following information is available in the troubleshooting section of all scale head manuals.
1. Make sure the cage is not hitting against anything (for example, the floor, dung, part of the frame). The only contact points must be the load cell and the stabilizer bar at the bottom of the cage.
2. Check to see if the load cell is crooked.
a. Remove any weight from the scale.
b. Press down on the scale and then release it.
c. Note the weight the scale head displays after settling.
d. Pull up on the scale and then release it.
e. Note the weight the scale head displays after settling.
If the two weight values are not the same, the load cell might be crooked.
3. Make sure the load cell bolt is hanging straight. If the bolt is crooked, it could be hitting against the side of the hole in the load cell and preventing a true reading.
Go around the scale and look from all angles to make sure the bolt is perpendicular (at a 90-degree angle) to the top of the load cell.
4. Check the internal condition of the load cell by using a multimeter on resistance mode (ohms-Ω). You do not have to disconnect the load cell from the cage to properly measure the resistance.
a. Switch off the power to the scale.
b. Disconnect the four load cell wires from the AutoSort Connect scale head. The wires are as follows:
- Green: excitation (+)
- Black: excitation (–)
- White: signal (+)
- Red: signal (–)
c. Measure the resistance between the excitation (+) and excitation (–) wires. The resistance should be 1100 +/- 50 ohms. If it is not, the load cell might be damaged.
d. Measure the resistance between the following wires.
- Excitation (+) and signal (–)
- Excitation (+) and signal (+)
- Excitation (–) and signal (–)
- Excitation (–) and signal (+)
A typical value for the resistance is 810 +/– 30 ohms. The important thing to check is that all four readings are within 3 ohms of each other. If the values vary by more than 3 ohms, the load cell might be damaged. Compare the values using a new load cell.
On the older-style load cells (bar-style, as opposed to "S"-style), the resistance measurements will be different, but the excitation-to-signal measurements should still be within 3 ohms of each other. The excitation measurement should be the amount stated on the load cell or its specification sheet.
5. Recalibrate the scale.