The LP7510 series of digital weight indicators has become a very popular line of scale controllers over the past decade. Many scale users like the price of these scale indicators and many also like how easy they are to setup and calibrate. Overall they work pretty well for many weighing applications. Of course like any weighing instrument, the LP-7510 will eventually fail or not work correctly. Below are some error codes and troubleshooting advice to consider.
Display shows UUUUUU
Reasons for the display to show all U’s….. Could be Overload, load cell connection or bad load cell. Ways to fix this, confirm the scale capacity and load cell capacity, check & inspect load cell connection and the load cell performance. You can try the following to see if this can be fixed. Check to see if the homerun cable that runs from the indicator to the junction box is damaged. If it is, replace the cable. If the cable looks good, open up the junction box and see if there is any water. If so, replace the junction box with summing board. You’ll also want to make sure all the wires on all 5 terminals are screwed into the terminal correctly. Tighten the screws even if the wires seem to be connected. You can then try to re-calibrate the scale. If none of this works, you probably need to either buy a new LP7510 weight readout or call your local scale company for a scale repair.
Display shows nnnnnnn
Reasons for the indicator to display all lower case n’s….. Could be a calibration issue, Load cell wiring, or load cell issue. Ways to fix this, confirm scale capacity and load cell capacity, calibration with correct weights, check load cells performance. You can try the following to see if this can be fixed. Check to see if the homerun cable that runs from the indicator to the junction box is damaged. If it is, replace the cable. If the cable looks good, open up the junction box and see if there is any water. If so, replace the junction box with summing board. You’ll also want to make sure all the wires on all 5 terminals are screwed into the terminal correctly. Tighten the screws even if the wires seem to be connected. You can then try to re-calibrate the scale. If none of this works, you probably need to either buy a new LP7510C weight readout with LCD display or call your local scale company for a scale repair.
Display shows ERR1
Error 1 refers to during calibration, weight is not used or the weight is above the max. capacity Use correct weight within the defined range.
Display shows ERR2
During calibration, the weight is below the minimum required weight. The calibration weight minimum is 10% of the max. capacity which is set in the C04 parameter. When doing a calibration, it is better to use 50% of the capacity or more as the test weight if possible.
Display shows ERR3
Error 3 refers to during calibration, the input signal is negative. Check load cells and load cell connections again. Then try to recalibrate.
Display shows ERR4
During calibration signal is unstable. Try re-calibration
Display shows ERR5
EEPROM Error Change PCB board likely.
Display shows ERR6
Error 6 says Exceed Zero Range. Likely need to order a new LP7510E weight indicator. You can try the following. Turn on the indicator and make sure nothing is on the scale, and that the scale is level. Press and hold the PRINT and HOLD keys simultaneously for a few of seconds until the display shows C01. Using the arrow keys, change C01 to C20. Once you have that, press the Print key to enter C20 parameter. Change the value of C20 on the right to 100 if possible using the up arrow key. If 100 is not available change to 20. Press PRINT key to enter your selection. The display will read C21 now. Press PRINT key to enter C21 parameter. Change the value on the right of C21 to 100 if available, 20 if not. Then press PRINT key to enter your selection. Display will read C22 now. Press TOTAL key to save and exit. Power the indicator off and then on, and see if this resolves the ERR 6 issue. If not, you may need a new weight indicator.
LP7510 Setup & Calibration
The typical color code for the 5 pin homerun cable for this instrument is below.
+EX RED Positive excitation voltage to load cell (pin 1)
+SIG GREEN Positive output signal from load cell (pin 2)
-SIG WHITE Negative output signal from load cell (pin 3)
-EX BLACK Negative excitation voltage to load cell (pin 4)
To setup and calibrate the LP7510 weight indicator do the following.
Press HOLD and PRINT together to access the setup menu. Shows C01.
Press PRINT to access the C1 level. The display should show [C1 #].
Press ZERO to choose which unit you want to calibrate in (1 = kg, 2 = lb).
Press PRINT to set the value. The display will now show C02.
Press PRINT to access the C2 level. The display should show [C2 #].
Press ZERO to change the setting to the decimal places desired
(The C2 level is used to adjust the decimal point on the scale. A value of 1 means there is one digit behind the decimal point.)
Press PRINT to set the value. The display will now show C03.
Press PRINT to access the C3 level. The display should show [C3 #].
Press ZERO to cycle through the values until the desired graduation appears.
(The C3 level adjusts the divisions on the scale. A value of 1 selected and C2 set to 1, the scale will read in 0.1 lb. increments.)
Press PRINT to set the value. The display will now show C04.
Press PRINT to access the C4 level. The display will show [######].
Enter in the maximum capacity you want to use for this scale by using UNIT and COUNT to move the cursor left and right, and TARE and ZERO to move the values down and up.
(The C4 level is used to enter in the max capacity of the scale)
Press PRINT to set the value. The display will now show C05.
Press PRINT to access the C5 level. The display should show [C5 0].
The C5 level calibrates zero on the scale. Make sure the scale is empty.
Press ZERO to change the value to 1.
Press PRINT. The display will count down from 10-1 while the scale is calibrating zero. When the display shows 0 the zero calibration is complete.
Press PRINT to continue. The display will now show C06.
Press PRINT to access the C06 level. The display will show [C6 0].
The C6 level is used to calibrate the scale with a known weight. Press ZERO to set the value of C6 to [C6 . Press PRINT. The display will flash SPAN, and then show [######].
Enter the calibration weight value you will use (at least 10% of max capacity you set in C04 by using UNIT and COUNT to move the cursor left and right, and TARE and ZERO move the values down and up.
Place the calibration weight you have on the empty scale and press PRINT.
The scale will count down from 10 to 0. Once 0 has been reached, the display will show CALEnd.
Press PRINT to continue. The display will now show C07.
Press ACCUM to save and exit the setup menu.
The scale has now been calibrated. The display will show the value of the calibration weight on the scale.
Unload the scale; the display should read 0.
Final Thoughts
Hopefully these instructions and troubleshooting tips have helped. One thing worth mentioning is the costs. Assuming you have the LP7510 connected to a floor scale…. At the time of this entry, a basic Inscale LP7510A weight indicator costs less than $300. A homerun cable is less than $100. A replacement j-box with summing board is less than $100. The point of these numbers is basically to remind you to not spend an entire day troubleshooting your scale. Likewise if you call the local scale company in to repair and troubleshoot your scale you’re going to spend hundreds of dollars before you ever get any item replaced.
If a floor scale is going to have a failure, typically it will either be a cut lp7510 homerun cable or a bad load cell. Don’t automatically assume the readout is causing the issue. You can examine your homerun cable in less than a minute. If it looks good, then walk the corners of your floor scale. Does each corner weigh you the same? If not, does one weigh you at an extreme? Odds are you have a cell issue. You can go one step further by opening the j-box in the scale and disconnecting one load cell at a time.