Section 8
Interface Board Calibration (old style)
R&P 2000 FRM PM 2.5 Air Sampler
1.0 Safety Notice: Proper anti-static protection must be used when taking measurements on any of the electronic boards and components. Failure to do so could result in damage to electronic components.
Only properly trained personnel should attempt to do this calibration; high voltages may be present. The possibility of shock or electrocution exists. Do not perform an Interface Board Calibration during wet or severe weather conditions.
2.0 Frequency: R&P recommends that calibrations be executed on an annual basis.
3.0 Interface Board: To get to the interface board you must remove the three screws from the display and key pad panel. Pull the panel forward to open the electronics compartment. The interface board is located on the bottom panel of the electronics compartment (Figure 1).
* Note: Voltage test point locations may differ depending on the style of the interface circuit board you have. If the monitor serial number starts out with 200FA, then it has the old style circuit board. If the monitor serial number starts out with 200FB, then it has the new style circuit board.
For the new style circuit board, refer to Section 8 Addendum.
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4.0 Calibration Procedure: This procedure describes the method for testing the 24 volt DC, 10 volt DC, 6 volt DC and 2.5 volt DC circuits.
Note: Location of voltage test points differ depending on the style of board you are working with.
4.1 Locate the red test point labeled A24V@ on the rear left section of the interface board.
4.2 Locate the black ground test point labeled AGND@ at the front portion of the board.
4.3 Confirm that the air sampler is connected to main power and that the sampler is turned on and in the Stop Mode.
4.4 Connect the positive lead of the multimeter to the red A24V@ test point.
4.5 Connect the ground lead of the multimeter to the black ground test point (Figure 2).
4.6 Observe the multimeter display to see if there are 24 DC Volts at this location. There is no adjustment to the 24 volt circuit. If there is not between 23.66-24 volts at this location there is a problem with the transformer. Correct voltage adjustments will not be able to be performed on the other circuits. The transformer will have to be replaced.
4.7 Locate the red test point labeled A6V@ at the front section of the interface board.
4.8 The black ground test lead should still be connected to the AGND@ test point.
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4.9 Connect the positive lead of the multimeter to the A6V@ test lead (Figure3).
4.10 Make sure that the LCD backlight is on when checking the A6VDC@ circuit. If the backlight is off, press any key on the keypad to turn it on.
4.11 Check the voltage to see that there is 6 VDC (0.05). If not, locate the horizontal pot that is silk-screened AR21@ located at the rear of the interface board. Adjust this pot until it reads six volts. This circuit controls the LCD display and the CPU board (Figure 4).
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4.12 Locate the red test point labeled A2.5V@ located at the rear left section of the interface board (Figure5).
4.13 Check the voltage to see that there is 2.5 VDC ( 0.002). If not locate pot AR53,@ located behind the test point. Adjust this pot until it reads 2.5 volts. This circuit controls the opening and closing of the flow controller (Figure 5).
Note: If the voltage is below 2 VDC the flow controller will rotate from open to close and continue through the filter cycle.
4.14 Locate the red test point labeled A10 V@ located at the rear of the interface board next to the 24 volt test point (Figure 6).
4.15 Check the voltage to see that there is 10.00 VDC ( 0.002). If not, locate pot AR44@ located at the rear of the interface board. Adjust this pot until it reads 10.0 volts. This circuit controls the Flow, Pressure and Temperature Sensors.
5.0 Analog Input Calibration: Once the Interface Board has been calibrated, the Analog Input calibration must be performed immediately after the voltage calibrations and before the temperature, pressure and flow calibrations.
5.1 Return the air sampler to the Main Menu and in the Stop Mode.
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5.2 Press <F5: Setup> key, then <F2: Calib> key.
5.3 Locate connector P18 which is located in the rear section of the interface board. Unplug the cable connected to P18 (Figure7).
5.4 Plug in the Analog Calibration Cable which was provided with the air sampler (Figure 8).
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5.5 Attach the red positive lead of the multimeter with (four-digit resolution) to the green test point labeled PWM1 located at the rear of the interface board. Attach the ground lead to the GND test point (Figure9).
5.6 Using the arrow key, position the cursor so that it is in the location labeled AA/O.@
5.7 Press <F1: Edit> key, to enter the Edit Mode. Type in a number between 0.050 and 0.150 volts and press <Enter>. Note: Factory uses 0.100.
5.8 Observe the number displayed in the row labeled AA/I@ in the column labeled ACalc.@ Ensure that this number does not vary more than 0.005 volts after watching it for five seconds. If this number is not stable, choose a new number from procedure 5.7.
5.9 Read the voltage displayed on the multimeter.
5.10 Using the arrow keys, position the cursor so that it is in the row labeled AA/I@ and the column labeled AAct.@
5.11 Press <F1: Edit> key to enter the Edit Mode. Type the voltage reading from the multimeter (to three digit accuracy, i.e., 0.xxx) in this position, then press <Enter>. This will automatically calculate the AOffset.@
5.12 Ensure that the number now displayed in the row labeled AA/I@ and the column labeled ACalc@ matches the number displayed on the multimeter within 0.005 volts.
5.13 Using the arrow key, position the cursor so that it is in the location labeled AA/O.@
5.14 Press <F1: Edit> key to enter the Edit Mode. Type in a number between 4.800 and 4.900 volts. Note: Factory uses 4.85.
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5.15 Observe the number being displayed in the row labeled AA/I@ in the column labeled ACalc.@ Ensure that this number does not vary more than 0.005 volts after watching it for five seconds. If this number is not stable, choose a new number from procedure 5.14.
5.16 Read the voltage displayed on the multimeter.
5.17 Using the arrow keys, position the cursor so that it is in the row labeled AA/I@ and the column labeled AAct.@
5.18 Press <F1: Edit> key to enter the Edit Mode. Type the voltage reading from the multimeter (to three digit accuracy, i.e., 0.xxx) in this position and press <Enter>. This will automatically calculate the ASpan.@
5.19 Ensure that the number now displayed in the row labeled AA/I@ and the column labeled ACalc@ matches the number being displayed on the multimeter within 0.005 volts.
5.20 Remove the multimeter leads from the interface board.
5.21 Remove the Analog Input Calibration Cable from location P18 and reinsert the cable connection into P18.
Note: After the analog input calibration has been performed successfully, the temperature, pressure and flow calibrations must be performed.
Note: If the air sampler has been reset and you have recorded the values of the AOffset@ and ASpan@ for the flow, you may enter these numbers directly when in the Edit Mode.
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