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CALIBRATION PROCEDURE
1. Set the switch to the LINE/RING position. Apply 40VDC between J1 and J2 (be sure J1 is positive), see
Figure 8. Adjust R5 so that the meter reads on the line at the start of the LINE OK area. (if 40V is not
available, apply 20VDC between J1 and J2, and adjust R5 so that the meter reads on the last line of the letter
"N" as shown in Figure 9).
2. Switch the input voltage of J1 and J2. The (REV POL) LED should light and the meter should read within
5% of the reading in step 1.
3. Set the switch to the LOOP position. Apply 20mADC between J1 and J2 (be sure J1 is positive). Adjust R1
so that the meter reads on the start of the LOOP OK area.
Example: For 20V use a 1k ; for 40V use a 2k
Mount the front panel to the case as shown in Figure K with four #4 x 1/2" phillip screws.
Figure 8
20V Position
Figure 9
TROUBLESHOOTING
1. Be sure that all of the components have been mounted in their correct position.
2. Be sure that all of the diodes have been installed correctly. The strip on the diodes should be in the same
direction as the stripe on the PC board.
3. Be sure that the LED has been installed correctly. The flat on the LED should be in the same direction as
the flat on the PC board.
One of the most frequently occurring problems is poor solder connections.
4. Tug slightly on all parts to make sure that they are indeed soldered.
5. All solder connections should be shiny. Resolder any that are not.
6. Solder should flow into a smooth puddle rather than a round ball. Resolder any connection that has formed
into a ball.
7. Have any solder bridges formed? A solder bridge may be caused by accidentally touching an adjacent foil,
by using too much solder or by dragging the soldering iron across adjacent foils. Break any bridges with your
soldering iron.
J2 (--)
R1
R5
40V Position
Power Supply
resistor.
J1
#4 x 1/2" Phillip Screws
-10-
J1
J2
Figure K
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