Underhill ICC Decoder Module Troubleshooting Guide
19
30
20
40
10
01
!
28.2 VAC
28.2 VAC
28.0 VAC
27.9 VAC
27.5 VAC
00.0 VAC
00.0 VAC
22.1 VAC
22.1 VAC
Observed Field Condition
18) “Is there a method to troubleshoot a break in the 2Wire path?
How to Troubleshoot
The following techniques can be used with a digital clamp meter that can measure AC
volts. A multi-‐meter is also suitable but requires each one of the 2Wire connections to
be opened to obtain a consistent reading which can be time consuming.
The diagram below shows how a digital clamp meter can be used to take
measurements along the 2Wire path is it enters and exists a valve box. Note that only
one of the wires is clasped inside of the digital clamp meter. In this example, the 2Wire
path is temporarily disconnected from the L1/L2 terminals and connected directly to
the 24-‐volt terminal block of the Hunter ICC power module.
This is done with the
120-‐volt power to the ICC controller “Off”.
Stations will
not
operate because they
are not receiving a “decoded” message specific to a station number. Using the
“halving method” take measurements along the 2Wire path at regular intervals.
Note the two measurements in “red” text showing a drop in AC voltage or none at all.
The drop in voltage indicates a nick or path to ground. Check field wire connections to
isolate the problem. The 0 volts AC, indicates a break in the 2Wire path. Locate and
repair the break as needed.
This is a simple diagram but your field wire layout could have branches or a “loop” to a
quick opening of valve boxes to confirm wire color and 2Wire path connections should
be conducted as part of this discovery phase.
Once all issues are resolved, disconnect the 2Wire path from the 24 VAC source and
reconnect to the L1/L2 terminals.