BT-JB1000

TRUCK SCALE BOARD

REV. F

QA (10/14/03) REV. 4

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Table of Contents Title Page # Introduction ------------------------------------------------- 3 Jumper Banks ------------------------------------------------- 3 Load Cell Jumpers ---------------------------------------- 3 Jumper 1 --------------------------------------------- 3 Jumper 2 --------------------------------------------- 3 Jumper 3 --------------------------------------------- 3 Section Trim Jumpers ------------------------------------- 3 Jumper 1 --------------------------------------------- 3 Jumper 2 --------------------------------------------- 3 Load Cell Connection ----------------------------------------- 4 350 Ohm -------------------------------------------------- 4 700 Ohm -------------------------------------------------- 4 1,000 Ohm ------------------------------------------------ 4 General Setup ---------------------------------------------- 5-7 Pots ----------------------------------------------------- 5 Load Cell Jumpers ---------------------------------------- 5 Section Trim Circuit ------------------------------------- 5 8-Cell Application --------------------------------------- 6 10-Cell Application -------------------------------------- 7 Troubleshooting -------------------------------------------- 8-9

List of Illustrations Figure 1. Board Layout --------------------------------------- 3 Figure 2. Schematic ------------------------------------------ 4 Figure 3. Trim Circuit --------------------------------------- 5 Figure 4. Layout of 8-Cell Truckscale ------------------------ 6 Figure 5. 8-Cell Truckscale Wiring --------------------------- 6 Figure 6. Layout of 10-Cell Truckscale ----------------------- 7 Figure 7. 10-Cell Truckscale Wiring -------------------------- 7 REV. 4 DATE RELEASED 10/14/03 QA (10/14/03) REV. 4

Introduction

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The B-TEK BT-JB1000 is a multi-ohm truck scale summing board as shown in Figure 1. This board will take 350, 700, and 1,000 Ohm load cells. It has great temperature stabilization, accurate tuning, and dependability. This board also offers simple troubleshooting due to the layout and architecture. It is competitively priced and has many benefits that other boards do not have.

Figure 1. Board Layout

Jumper Banks There are 5 jumper banks. Each cell has a 3 jumpers. The section trim area has 2 jumpers. Fig. 2. shows the schematic layout of all the jumpers on the board. Load Cell Jumpers Jumper 1 - If jumper (1, 4, 7, or 10) are closed, the 6.98 K and the 10 K resistors are shorted. This leaves only the pot in the trim circuit as shown in Figure 2. Jumper 2 - If jumper (2, 5, 8, or 11) are closed, the 6.81 K resistor is placed in series with the 100 K pot as shown in Figure 2. Jumper 3 - If jumper (3, 6, 9, or 12) are closed, the 10 K resistor is placed in series with the 100 K pot as shown in Figure 2. Jumpers 2 & 3 - If jumpers (2 & 3, 5 & 6, 8 & 9, or 11 & 12) are closed, the 6.81 K and 10 K resistors are in parallel (4.05 K). These are placed in series with the 100 K pot as shown in Figure 2.

Section Trim Jumpers Jumper 1 - If jumper 13 is open, the section trim circuit is removed from cells 1 & 2 as shown in Figure 2. Jumper 2 - If jumper 14 is open, the section trim circuit is removed from cells 3 & 4 as shown in Figure 2. QA (10/14/03) REV. 4

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Figure 2. Schematic

Load Cell Connections

Jumpers 1, 2, and 3 are used to switch from 350 Ohm, 700 Ohm, and 1,000 Ohm load cells. The 100 K pot is then used to fine-tune the cells. The 100 K pots will all be at mid-range Ohms. Jumper 1 is simply a short across the 6.81 K and 10 K resistors in each cell trim circuit. This gives another range of adjustment. Figure 3. gives a close up view of the trim circuit. 350 Ohm Jumpers 2 & 3 should be closed for each load cell bank (1-4). This will place the 6.81 K and 10 K in parallel. The corresponding resistance should be 4 K Ohms in series with the 100 K pot as shown in Figure 3. Jumper 1 should be open. 700 Ohm Jumper 2 should be closed for each load cell bank (1-4). This will place the 6.81 K in series with the 100 K pot as shown in Figure 3. Jumpers 1 & 3 should be open. 1,000 Ohm Jumper 3 should be closed for each load cell bank (1-4). This will place the 10 K in series with the 100 K pot as shown in Figure 3. Jumpers 1 & 2 should be open. QA (10/14/03) REV. 4

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Figure 3. Trim Circuit

General Setup Pots -All pots are shipped at maximum Ohms. CW - INCREASE CCW - DECREASE Load Cell Jumpers (Full Electronic) Load Cell Jumpers (Electro-Mechanical) -Jumpers 1 & 3 are open in all cell trim circuits. -Jumper 1 is open in all cell trim circuits. -Jumpers 2 is closed in all cell trim circuits. -Jumpers 2 & 3 are closed in all cell trim circuits. -This is the setup for a 700 Ohm board. -This is the setup for a 350 Ohm board. Section Trim Circuit -Jumpers 1-2 are closed. This enables all section trim capabilities.

The pots are more stable in the upper range of resistance (i.e., the resistance doesn’t change as rapidly in the upper range of the pot). For this reason we suggest starting with all pots at maximum resistance. Then find the lowest weight reading for all the cells with pots at maximum resistance. Adjust all other cell trim pots down to the lowest cell weight reading. This will give you the absolute maximum resistance on all the pots and allow for more accurate adjustment. QA (10/14/03) REV. 4

8-Cell Application

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Figure 4. Layout of 8-Cell Truckscale

Figure 4. Shows a typical layout of load cells and boxes. Cells 1-4 go to box #1 and cells 5-8 go to box #2. The weight indicator is then connected to the first board connection marked “Indicator” as shown in Figure 5. All the other wiring is as shown for an 8-Cell application.

QA (10/14/03) REV. 4 Figure 5. 8-Cell Truckscale Wiring 10-Cell Application

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Figure 6. Layout of 10-Cell Truckscale Figure 6. Shows a typical layout of load cells and boxes. Cells 1-4 go to box #1, cells 5-6 go to box #2, and cells 7-10 go to box #3. The weight indicator is then connected to the second board connection marked “Indicator” as shown in Figure 7. The jumper J14 should be open to eliminate the unused section. All the other wiring is as shown for a 10-Cell application.

Figure 7. 10-Cell Truckscale Wiring

QA (10/14/03) REV. 4

Troubleshooting

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1. Terminal block points (all jumpers open) A. With one test lead on -EXC on Indicator terminal block, test all other -EXC points on continuity setting. All should be a short. B. With one test lead on +EXC on Indicator terminal block, test all other +EXC points on continuity setting. All should be a short. C. With one test lead on SHLD on Indicator terminal block, test all other SHLD points on continuity setting. All should be a short. D. With one test lead on -EXC on Indicator terminal block, test if -SEN is shorted. E. With one test lead on +EXC on Indicator terminal block, test if +SEN is shorted. F. Test each terminal block for unwanted shorts. 2. Resistance at Indicator -SIG to +SIG(Nominal values). Resistors Pots at Max Pots at Min Measured Calculated Measured Calculated 10K 19,230.21 - 22,603.59 3,423.51 - 3,445.80 6.81K 18,905.23 - 22,267.78 3,365.44 - 3,386.02 4.05K 18,618.33 - 21,972.31 3,293.98 - 3,312.25 0K 18,186.90 - 21,529.64 3,117.79 - 3,129.68 If step #2 fails, each component needs to be measured. 3. Resistors from top side of board (all jumpers open) A. R1-R2, R5-R6, R9-R10, R13-R14, and R19-R22 2.4975K - 2.5025K Ohms B. R3, R7, R11, and R15 6.742K - 6.878K Ohms C. R4, R8, R12, and R16 9.9K - 10.1K Ohms D. R17 and R18 2.465K - 2.515K Ohms 4. Pots from bottom side of board (all jumpers open) A. Test pots P1 - P6 at minimum resistance 0K Ohms B. Test pots P1 - P6 at maximum resistance 90K - 110K Ohms 5. Section trim circuit (all cell jumpers open) A. (Cells 1&2) jumper J13 closed only. Check resistance at Indicator -SIG to +SIG. R = R17 + P5 + 5K R = B. (Cells 3&4) jumper J14 closed only. Check resistance at Indicator -SIG to +SIG. R = R18 + P6 + 5K R = 6. -/+ signals to each cell A. (Cell 1 -SIG) Check the resistance from Indicator -SIG to Cell 1 -SIG. ≈ (5K Ohms) B. (Cell 1 +SIG) Check the resistance from Indicator +SIG to Cell 1 +SIG. ≈ (5K Ohms) C. (Cell 2 -SIG) Check the resistance from Indicator -SIG to Cell 2 -SIG. ≈ (5K Ohms) D. (Cell 2 +SIG) Check the resistance from Indicator +SIG to Cell 2 +SIG. ≈ (5K Ohms) E. (Cell 3 -SIG) Check the resistance from Indicator -SIG to Cell 3 -SIG. ≈ (5K Ohms) F. (Cell 3 +SIG) Check the resistance from Indicator +SIG to Cell 3 +SIG. ≈ (5K Ohms) G. (Cell 4 -SIG) Check the resistance from Indicator -SIG to Cell 4 -SIG. ≈ (5K Ohms) H. (Cell 4 +SIG) Check the resistance from Indicator +SIG to Cell 4 +SIG. ≈ (5K Ohms) QA (10/14/03) REV. 4

7. Formula for board resistance RC1 = R1 + R2 + P1 + (R3, R4, or R3 || R4) RC1&2 = (RC1 x RC2)/(RC1 + RC2)

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RC2 = R5 + R6 + P2 + (R7, R8, or R7 || R8) RC3&4 = (RC3 x RC4)/(RC3 + RC4) RC3 = R9 + R10 + P3 + (R11, R12, or R11 || R12) RS1 = R17 + P5 RC4 = R13 + R14 + P4 + (R15, R16, or R15 || R16) RS2 = R18 + P6 R1&2 = {[( RC1&2 x RS1)/( RC1&2 + RS1)] + R19 + R21} R3&4 = {[( RC3&4 x RS2)/( RC3&4 + RS2)] + R20 + R22} RT = ( R1&2 x R3&4)/( R1&2 + R3&4) The above formula can be used to exactly compute the resistance of a board. If more than one board is in a circuit then parallel the resistance of each board. The values of each individual component must be known to compute this resistance, so each component will have to be isolated. 8. Resistor and pot values Cell 1 Cell 3 Section 1 & 2 R1 = R9 = R17 = R2 = R10 = R19 = R3 = R11 = R21 = R4 = R12 = P5 = P1 = P3 = Cell 2 Cell 4 Section 3 & 4 R5 = R13 = R18 = R6 = R14 = R20 = R7 = R15 = R22 = R8 = R16 = P6 = P2 = P4 = Note: 1. Please allow ample time for weight indicator circuits to warm up and stabilize(1/2 hour to 1 hour) before determining a drifting problem exists with the scale. 2. High degrees of temperature change will not cause a span change, but could cause a zero change do to the temperature coefficient of the pots. To counter a zero change with extreme temperature change zero tracking should be on. 3. The board must be dry at all times, so make sure there is a good seal around the lid of the box, a good seal on any unused cord grip connectors, and a desiccate bag to absorb moisture in the box. 4. There cannot be two grounded ends of the load cell shield cable. If both ends are grounded, a ground loop will be introduced and cause scale drift. The load cells typically have an isolated ground. The cable should be grounded at the weight indicator only. This is also essential for lightning protection. 5. Always check cables for nicks or cracks in insulation. This may cause scale drifting. 6. Make sure all cable connections are properly placed and secure in terminal blocks, but do not over tighten terminals (strip screw). 7. Make sure cable wire ends are soldered and dry. Non-soldered ends will not make a good connection and wet ends will cause scale drift. 8. Any unused cells or sections should have jumpers removed. QA (10/14/03) REV. 4

Junction Box Seal

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The cable should run thru the lock hole on the base and the latch hole on the lid. The latch will not be able to open and the seal will break if the lid is opened.

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