Eagle Microsystems C7200P - Manual (Page 6)

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3. Check all connections by lightly pulling on each lead. Tighten terminal connections as
needed.
4. If problem persists, press lightly on the circuit board itself and check meter response.
Replace board if required.
Note: Make sure when replacing the cover that the box is dry and the cover is tight.
R1
R1 R1
R1 R1
+EXCT
+ -
-EXT +SIG -SIG
SHLD
+E -E +S -S SH
+E -E +S -S SH +E
-E
+S -S SH
+E -E +S -S SH
EAGLE MICROSYSTEMS
SJB4-S
FIG. 3
5.2 Checking the load cells.
1. Load Cell resistance test:
a. Disconnect the load cells from the Summing Box and measure the resistance as shown in
Figure 4.
b. Any electrical leakage between the leads and the load cell case is usually caused by moisture
leakage into the load cell or by moisture in a damaged load cell cable.
c. If a load cell does not pass the above resistance tests, replace it with a known good one.
2. Load Cell zero shift test:
a. Remove the top frame of the scale. (see section 5.3)
b. Connect a DC power supply of 10 or 15 volts to the Red (+) and Black (-) excitation load cell
leads.
c.
The measured output between the Green (+) and White (-) signal leads should be less
than 5 millivolts.
d. An output signal greater than 5 millivolts indicates a zero shift caused by mechanical
overload.
e. If the output signal is between 5 and 15 millivolts, the load cells zero has shifted but will
probably still continue to work.
f.
If the output signal is greater than 15 millivolts, the load cell should be replaced with a
known good one.
N O T E : If the load cell's zero has shifted due to a mechanical overload, the reason for the
overload should be determined before a new load cell is installed.
5.3 REPLACING THE LOAD CELL
Call the factory to advise that the load cell is defective. Report model and serial numbers for both load cell
and scale.
1. Remove all ton containers from scale.
2. Remove plastic caps from top frame.
3. Use 3/4" deep socket to remove hex nuts inside top frame on all four load cells .