640 Calibration

Weigh-Tronix uses two methods for calibration. A standard or a custom calibration method. If

you have a scale on a grain cart is it recommended to use the CUSTOM CALIBRATION

METHOD. The vast majority of indicators purchased will come calibrated out of the box. A

final adjustment is usually required for most GRAIN CARTS.

For all Grain Carts use a STANDARD CONFIG number of 98 for the first two digits. Once

again, this is under the CONFIG menu option. The THIRD digit is the increments of weigh

display. For a grain cart it is best to use a 3 for a 10 lb update or 4 for a 20 lb update or 5 for a

50 lb update. We should have the CONFIG number of 983 or 984 or 985 based off of your

preference.

If you want to use a printer, make sure the 4th digit on the CONFIG number is a 9. For Example

the CONFIG number could be 9839, 9849,9859 at this point.

The last placeholder should be a zero. The Final CONFIG number should be 98300 or 98390 or

98400 or 98490 or 98500 0r 98590. Once again the 9 is set up as a print command. It does not

hurt anything is you have the 9 in the CONFIG number.

The CUSTOM NUMBER for calibration can be found on page 16 of your 640 M manual. One

thing to note on the Central City Scale System in a 3 bar grain cart can weight out as a 4 bar

system, because of the resistor in the junction box on some units. With the resistor involved

your CUSTOM NUMBER should be 37500 to begin with. If you do not have the resistor the

CUSTOM NUMBER would be 27775. The grain cart systems are labeled as 2-1/4 Dual

bars. The easiest way to tell if you have a resistor or not is to identify if the junction box has

external 5 pin plugs. If it has the plugs it would weigh out at 4 of the 2-1/4 dual weigh

bars. You then would use the CUSTOM NUMBER of 37500. If the wires for the junction box

are hard wired into the junction box you would use the CUSTOM NUMBER of 27775. All 5

weigh bar Weigh-Tronix systems do not use the resistor so a typical starting point for this

scenario would be 98590 for the CONFIG and a CUSTOM of 45000.

The easiest way to see if you have the correct CUSTOM NUMBER is to stand on the hitch while

it is hitched up to the tractor. (It will not read accurately if the jack stand is being used.) If the

weight is off you can use the formula below to adjust the CUSTOM NUMBER. The videos

below will also help guide you through the process.

CALIBRATION FORMULA = ACTUAL WEIGHT ÷ BY INCORRECT WEIGHT x THE

CUSTOM NUMBER. One thing to note is that the custom number is just a starting point and

not a constant. As you get closer to the correct weight the CUSTOM NUMBER will stabilize

within 1% or so.

EXAMPLE Truck goes to a certified scale and reads 58,654 LBS and the grain cart gave a

reading of 59,240 LBS.

Let's say we have a 3 bar Weigh-Tronix grain cart system with a junction box that has a

resistor. Our current numbers would be 98390 for the CONFIG ( remains) and 37500 for the

CUSTOM NUMBER.

ACTUAL = 58,654 ÷ 59,240 =.99010804 therefore 37500 x .99= 37129 is the NEW CUSTOM

NUMBER. You make want to do a few more calibrations to verify the accuracy.

How to change the 640M/640/640XL CONFIG number, CUSTOM number and AZT

1. Press and hold the HOLD/MENU keys for three beeps. "SET.PAS" will be displayed.

2. Using the RM and HOLD/MENU key, enter "640". (RM will increase the number and

HOLD/MENU shifts over to enter the next digit.)

3. Push the PRINT/SELECT key twice. Indicator will read "CONFIG".

4. Push the PRINT/SELECT key. The last config number appear.

5. Use the RM key to change the number and HOLD/MENU key to shift over to the next digit.

6. When the new CONFIG number is entered push the PRINT/SELECT key and "CONFIG"

will be displayed. (If you are only changing the CONFIG number skip TO step 14.)

7. Press HOLD/MENU key "CUSTOM" will be displayed.

8. Press PRINT/SELECT key. The last custom number will appear.

9. Use the RM key to change the number and HOLD/MENU key to shift over to the next digit.

10. When new CUSTOM number is entered push the PRINT/SELECT key and "CUSTOM"

will be displayed.

11. To change "AZT" repeatedly push the HOLD/MENU key until AZT appears.

12. Push the PRINT/SELECT key. The last AZT number will be displayed use the

HOLD/MENU key to change the number.

13. Push the PRINT/SELECT key and "AZT" will be displayed.

14. Push the G/N key twice and the indicator will display "busy" and return back to weighing to

mode.