ACC Decoder System Troubleshooting Guide

ACC Decoder System Troubleshooting Guide
Issue:
Finding a Break in the 2-Wire Path
Tools:
Digital Multimeter (DMM) with Min/Max function (Fluke Model 12 or similar),
known-good test solenoid, approved wire connectors
Diagnostics: Start with an as-built drawing if possible to aid in locating wire paths and
decoders. Run a test program (press and hold Program button for about 3
seconds with dial in Run) from the facepack starting at the stations/decoders
closest to the controller, or create and start a dummy program with the furthest
station/decoder that is known to function properly. Let the test program run
until you are able to verify the last known functioning, and the first faulting,
stations/decoders.
Put the controller in the “OFF” position.
Check the voltage across the blue and red terminals of the ADM. Use the DMM
in DC volts position and Min/Max function on.
The voltage should read between 32V to 36V. If not, check the controller
source voltage.
Remove and inspect the connections at the last known functioning
station/decoder.
Use the DMM with Min/Max function on, to check the voltage on the two-wire
path from the controller. Should read between 20V to 36V (without the Min/Max
feature, the voltage will appear as a pulsing value and is impossible to read
accurately).
If the voltage is below the 20-36V level, see procedure for Finding Short on 2Wire Path.
If voltage is correct, reconnect the decoder temporarily using wire nuts until
diagnostics are complete.
Continue diagnostics by removing and inspecting the connections of the first
faulting station/decoder.
Use the DMM to verify the voltage on the wires that come from to the controller
read between 20V to 36V.
Reconnect the decoder to the two-wire path from the controller only and read
the voltage. Again it should read between 20v to 36V. If not, the decoder is
faulty. Replace the decoder.
If the voltage is within limits, disconnect the current decoder connections and
twist the red and the blue wires together. Go back to the last known functioning
station/decoder.
Disconnect all wiring connections.
ACC Decoder System Troubleshooting Guide
Put the DMM into resistance ( ) reading mode (see DMM users manual).
Read the resistance of the wire pair that connects the two decoders together.
The readings should be between 0-60 depending on distance between
decoders (see decoder wire resistance chart). If connection/wiring breaks are
not visible, then use a cable tracer to track the wire issue.
Issue:
A decoder or decoders do not activate a valve/relay
Tools:
DMM, known-good test solenoid, approved wire connectors
Diagnostics: If a single decoder is not able to activate a valve/relay, verify that the decoder
was programmed with the proper decoder station/address number. If address is
correct, verify proper connections on the output side of the decoder (to the
solenoid wires).
Disconnect the solenoid(s) from the decoder output. Check the resistance of
the solenoid(s) with the DMM. A single solenoid will have 20 – 35 of
resistance depending on solenoid type.
If there are 2 solenoids attached to a single output, the resistance value will be
~ ½ of one solenoid. Remember each output is design to handle a maximum
of 2 solenoids or 1 relay. If there is anything outside this resistance range, there
is something wrong with the solenoid, and it should be replaced.
If the values are in range, reconnect the solenoid(s) and connect the probes of
the DMM to the appropriately colored wire pair for the station number in
question.
Set the DMM to DC volts, Min/Max mode, and check the voltage on the output
of the decoder. Attempt to turn on the decoder from the controller (Manual
Single Station or ICR remote).
Check the voltage on the output of the decoder. If the voltage did not change,
verify that the decoder was programmed with the correct station number.
If the voltage is greater than 20V, replace the solenoid.
If the voltage is less than 5V, then remove the solenoid. Does the
voltage increase to greater than 20V? If yes, then replace solenoid.
If the voltage remains the same, then replace the decoder.
If the decoder does not function properly after being replaced, go to
issue „Find a Short on the 2-Wire Path‟.
Issue:
Station Fault – (Overcurrent)
Tools:
Diagnostics: See „A decoder or decoders do not activate a valve/relay‟. If resistance in the
field wiring is low, voltage is lower, and this can cause the Overcurrent message.
Issue:
Station Fault – (Damaged)
ACC Decoder Troubleshooting Guide
Preliminary
Hunter Industries Incorporated The Irrigation Innovators
1940 Diamond Street San Marcos, CA 92078 TEL: 1 (760) 744-5240
www.HunterIndustries.com
3/07
FAX: 1 (760) 744-7461
2
ACC Decoder System Troubleshooting Guide
Tools:
none
Diagnostics: Replace Decoder. This indicates non-repairable internal damage.
Issue:
ADM / Decoder Module Alarm (Overcurrent)
Tools:
Diagnostics: If the „Module/Line Status‟ LED is continuously flashing red for greater than 1
minute, go to section „Find a Short on the 2-Wire Path‟.
If the LED is flashing red only after a group of stations/decoders was turned on,
activate the stations/decoders, one at a time.
Does each one of the stations/decoders activate the solenoid/relay?
If not, go to issue „A decoder or decoders do not activate a valve/relay‟.
If the LED is flashing red only after a station/decoder was turned on, go to issue
„A decoder or decoders do not activate a valve/relay‟.
Issue:
Find a Short on the 2-Wire Path
Tools:
DMM, compatible Clamp-on Current Sensing Module, known-good test
solenoid, approved wire connectors.
Diagnostics: Remove all wire paths from ADM (decoder output module in controller).
Use the DMM to check the resistance of each 2-wire path (Ohm or position).
If the resistance reads less than 10k (10,000) on any of the paths, continue
troubleshooting that wire path. Resistance conditions lower than 15 will cause
an Overcurrent message to appear in the controller display.
Connect one of the faulted paths to a 24VAC (100VA or greater) power source.
Do not use the 24VAC output of the Master Module in the ACC controller
(insufficient current for this test).
Place the DMM in mV, AC mode.
Use the Clamp-on Current Sensor and the DMM combination to view the
current on the wire path.
Start at the power source.
Note the current and continue down the wire path checking the current every
500 ft. The current should drop 3mA to 5mA for every decoder passed.
If the current drops off significantly, you have passed the shorted area. Work
your way backwards until you find the shorted segment.
Check the wires leading to the decoder from the wire path to see if the decoder
is shorted. Repair wiring as necessary.
Repeat diagnostics for each of the wire paths faulted.
ACC Decoder Troubleshooting Guide
Preliminary
Hunter Industries Incorporated The Irrigation Innovators
1940 Diamond Street San Marcos, CA 92078 TEL: 1 (760) 744-5240
www.HunterIndustries.com
3/07
FAX: 1 (760) 744-7461
3
ACC Decoder System Troubleshooting Guide
You may use a ground fault tester to find the location of the short- disconnect
controller from two-wire path first!
Issue:
Station Fault – Comm
Tools:
none
Diagnostics: This issue may have several possible causes. The first possibility is an open
circuit in the two-wire path. Are decoders after the decoder in question
activating the station/relay and communicating? If not, see issue „Finding a
Break in the 2-Wire Path‟.
The second possibility is the station/decoder number of the decoder. Is the
decoder activating the solenoid/relay? If the solenoid/relay is not being
activated, then remove the decoder from the system. Use the programming
port to verify that the decoder is able to communicate by displaying the station
number. Change the station number if it is not correct.
If the decoder is not communicating with the programming port, then see issue
„Decoder not Programming on Programming Port‟
The third possibility is that the 2 wire path is shorted at or near the decoders
with the Comm Fault. See issue „Find a Short on the 2-Wire Path‟.
Issue:
Decoder not Programming on Programming Port
Tools:
none
Diagnostics: The Programming Port is a useful tool to determine if a decoder is alive. Test
the Programming Port voltage using a DMM in DC volts, with „Min/Max‟ setting
selected (the normal operating voltage pulses within a range).
Plug the probes into the Programming Port holes and measure the port voltage.
If the voltage is between 13V and 16V Max and -13V and -16V Min, the
Programming Port output is functioning.
If not, or if Min/Max readings are well outside the range, remove the ADM from
the controller. Open the ADM and look at the spring contacts on the board
assembly that align with ports, to see if they are clean and have tension.
Reassemble the ADM and return to the controller. Retest the voltage.
If the voltage is within range, connect the decoder to Programming Port. Turn
the facepack dial to the „ADVANCED FEATURES‟ position and select „Decoder
Functions‟ then select „Program Decoder‟.
If the Programming Port does not detect the decoder, then try to program a
known good decoder. If the known good decoder can be programmed, then
replace the defective decoder.
If the Programming Port continues to fail, then replace the ADM.
ACC Decoder Troubleshooting Guide
Preliminary
Hunter Industries Incorporated The Irrigation Innovators
1940 Diamond Street San Marcos, CA 92078 TEL: 1 (760) 744-5240
www.HunterIndustries.com
3/07
FAX: 1 (760) 744-7461
4
ACC Decoder System Troubleshooting Guide
Issue
No decoder functions
Cause
Decoders are not Addressed
No ADM Output
Short Circuit in Two-Wire path
Open Circuit in Two-Wire path
Short Circuit in Two-Wire path
Decoder Output Short (seen
only when decoder is active)
May Happen within 3000ft
ADM Fault - Overcurrent
Station Fault – Comm
Decoder is not Addressed
Station Fault – Damaged
Station Fault – Overcurrent
Decoder not Programming on
Programming Port
Line Status Light Blinking
Line Status Light Off
Rw = Wire Resistance
Cable
(1 pair)
#14-2
2.0mm-2
#12-2
2.5mm-2
#10-2
Open Circuit in Two Wire Path
Short Circuit in Two-Wire path
ADM Receiver Not Functioning
– no communications with field
Decoder is Internally Damaged
Decoder Output Short (seen
only when decoder is active)
May happen further than 3000ft
from controller
Decoder is Damaged
Spring Contacts inside ADM are
not making Contact
ADM Programming Port
Damaged
Damaged ADM Output
ADM Fault - Overload
Controller Source Off
Damaged ADM Output
Rw
ohm/1000ft
5.04
~
3.18
~
2.00
ACC Decoder Troubleshooting Guide
Preliminary
Hunter Industries Incorporated The Irrigation Innovators
1940 Diamond Street San Marcos, CA 92078 TEL: 1 (760) 744-5240
www.HunterIndustries.com
Fix
-Program Station Numbers in
Decoders
-Check Power to Controller
-Replace ADM
-Find Short and Repair
-Find Open and Repair
-Find Short and Repair
-Replace Solenoid
-Find Short in Output Wiring
and Repair
-Replace Decoder
-Program Station Number in
Decoder
-Find Open and Repair
-Find Short and Repair
-Replace ADM
Formatted
-Replace Decoder
-Replace Solenoid
-Find Short in Output Wiring
and Repair
-Replace Decoder
-Replace Decoder
-Clean Contacts
-Contacts are Bent
-Replace ADM
-Replace ADM
-See „ADM Fault – Overload‟
-Check Power to Controller
-Replace ADM
Rw
ohm/km
16.56
10.98
10.42
7.02
6.55
Comment
IDWIRE1
Metric Wire Gauge
IDWIRE2
Metric Wire Gauge
American Wire Gauge
3/07
FAX: 1 (760) 744-7461
5
Download PDF