Electro-Chemical Devices (ECD) R350D - Manual (Page 10)

Page 4 Remote Display
3.0 CALIBRATION
The meter is supplied calibrated to read 000
for4mAloop current and 1000 for 20mA.
To re-calibrate, place the Jumper Link across LK1. This
disables the Offset adjustment to enable Span
adjustment to be made first. After Span adjustment is
complete, the Jumper Link is removed and the Offset
adjustment is made. The Jumper Link is then used to
display one of the decimal points if necessary.
Example to re-calibrate: Meter to read 02.00pH at 4mA and 12.00pH at 20mA.
1.
Calculate the Span by subtracting the desired reading at 4mA from the desired reading at 20mA:
12.00 - (2.00) = 10.00
2.
Remove the Jumper Link used to select the Decimal Point and place it across Link Lk1. Link Lk1 is
located to the left of the screw terminals.
3.
Apply 16mA between the + and - screw terminals.
4.
Adjust the Span potentiometer so the R350D indicates 1000.
5.
Remove Jumper Link Lk1 and place it back on the desired Decimal Point (DP2 in this case).
6.
Apply 4mA between the + and - screw terminals.
7.
Adjust the Offset potentiometer so the R350D indicates the desired reading at 4mA: 2.00
8.
Adjust the Span and Offset as necessary for optimum accuracy. First apply 20mA and adjust
Span until the reading is 12.00. Then apply 4mA and adjust Offset until the reading is 2.00.
Repeat step 8 until correct readings are obtained at 4mAand at 20mA.