Automower-fans

Hello All! I found this site after doing a Google search related to my problem. While I studied French in high school, fortunately, Google Chrome helps with the translation (otherwise I'd be in trouble).

Anyway....

I've had my Automower (model 315x) since early February--fresh installation made then of the boundary wire and guide wires (buried with a machine about 2" deep).

A few weeks ago, I had some grass sod installed. During the preparation and yard tilling, the landscaper pulled up the boundary wire in two locations. I repaired the breaks with no problems. All my previous repairs (twice now with sidewalk edger) have been made with twisting the wires, soldering and insulating tape wrapped around the soldered connection.

Unfortunately, after the repairs were made, I still have a flashing blue light (about 2 second intervals) on the mower base station indicating a broken boundary wire. I swapped the guide wire around (my model only has one guide wire) with the boundary wire connections and was able to determine which segment of my boundary wire has a problem--this section is about 400 feet long by my estimate. The good boundary wire segment is about 1050 feet. My guide wire is about 430 feet.

I have a resistance of 937ohms across the boundary wires. Since I do have "some" continuity, the toner and AM radio methods have proven fruitless to find my problem since I don't have a total break in the wire.

Resistance across the guide wire and good boundary segment is 8 ohms--so that looks good to me.

I read in a post on this site back from 2016, that some people use the HV-output of an electric sheep fence to help break the high resistance connection and make a full break that can then be tracked down.

Can anyone share anymore details regarding the electric fence approach? I have an electric fence module used on a friend's farm to try out. Do I connect one end of the boundary wire to the HV-output and the other boundary wire end to the ground output? Assuming the fence option doesn't work, can anyone share what other approach I should take to solve my problem?

Thank you in advance to the community and any assistance that can be offered!

-AUEngineer
Mobile, Alabama, USA

Hi

[quote ] All my previous repairs (twice now with sidewalk edger) have been made with twisting the wires, soldering and insulating tape wrapped around the soldered connection.
[/quote]
This will lead to bad connections in a few months / years, depending on rain and soil moisture level. Avoid solder, crimping is better suited (+ insulation), or special connection systems like scotchlock.

AM radio can lead to good result if you only connect one side of the wire. Or, alternatively, connecting both sides and listening to a change in the generated noise. Left and right wire generate a very different tune and the change can be detected over a few meters of the bad connexion.

Alternatively, you can "burn" the bad connexion with the so called "fence option". With all the wires disconnected from base station, you simply make a high voltage shortcut, by connecting both sides of the bad segment to both sides of the fence HV output (typically ground and HV).

Last option, open bad segment in the middle, check which side of the segment is in defaut with ohmmeter and a long wire, then do it again until only some reasonable length is in default, which you simply remove and change (cable will break on weak part).

Thank you, Razmoket, for your response and guidance.

Good news! The robot is mowing again....

The electric fence successfully "burned open" the high resistance spot in the boundary wire, making it quick and easy to find the break with the AM radio. Once I had the right equipment and procedure, the entire situation was rectified in about 30 minutes (after 3+ weeks of frustration).

The wire "nick" looks to have been made by a shovel while flowerbed work was being completed.

As suggested, I made the repair with a crimped heat shrink connector, and covered the connector (after heating and cooling) with insulating black tape for extra good measure.

-AUEngineer

Brilliant! I am just down the road from Mobile where you are and spent an hour in the hot midday sun trying the AM radio method which found an area of weak signal but not conclusive. I tried your suggestion with the electric fence module, and in seconds I could hear the "pop, pop, pop" of the HV arc out in the yard. I repaired the cut wire, but I also found another weak spot that was popping. However, since I had the green light I left it alone for now. This method beats all others for me. My wire is not buried deep except by grass and a little silt so easy to hear the arc. Thanks a million for the idea! The elec fence I used was a 0.5 joule FiShock. BTW there was 350 ohms of resistance in the affected wire. Guess I should check again now that it is patched to see status of the "weak" spot, but it is working now. Thanks again!