American Magnetics 185 & 186 Liquid Level Instruments (CE-Marked) - Manual (Page 74)

64 Rev. 3
Service Guide
Unit not responding to communications
7. Verify the sensor is free of contaminants and not subject to any
physical distortion. Disconnect the BNC connector at the top of the
sensor and measure the sensor resistance by placing an ohmmeter
across the center pin and the outer barrel of the connector. The
resistance of the sensor should typically be >10 M Ω .
7.1.3 Controller output does not energize
Warning
This procedure is to be performed only when the instrument is
completely de-energized by removing the power-cord from the power
receptacle. Failure to do so could result in personnel coming in
contact with high voltages capable of producing life-threatening
electrical shock.
1. Verify continuity of controller output fuses, F2 and F3, located on
the instrument printed circuit board.
a. Ensure the instrument is de-energized by disconnecting the
power cord from the power source. Disconnect the power cord
from the connector located on the rear panel of the instrument.
b. Remove the instrument top cover and check the fuses F2 and F3
for continuity.
c. If a fuse is bad, replace with a 2.5A IEC 127-2 Type F Sheet II
5x20mm fuse.
d. Check your connected equipment for compliance with the
output receptacle rating.
Caution
Installing fuses of incorrect values and ratings could result in
damage to the instrument in the event of component failure.
2. Replace the fuse and securely fasten the instrument top cover.
Reconnect the power-cord.
7.1.4 Unit not responding to communications
1. Verify your communications cable integrity and wiring. See the
Appendix for DB-25 to DB-9 translation for RS-232 cables.
2. Check to make sure you are sending the correct termination to the
instrument. If you are using the serial option, make sure the echo
feature is set correctly for your application and the baud rate
matches the setting of the host device. If you are using the IEEE-