Robot lawnmower guide wire repair

[littlespark]

My friend has got one of those robot lawnmowers that automatically goes out once a day and runs around the grass.

There is a single core guide wire buried around the perimeter of the lawn that must carry a signal that the mower senses and knows not to cross…

This wire has a break in it somewhere.


Is there an easy trick, or tool that can be used to find out how far along the wire the break is…. Or is it likely non repairable and needs replaced?


He’s already tried a continuity test with a simple multimeter, which showed an open circuit between the two ends…. But that might just be the lack of capability of a simple meter.

I could shove main voltage down it and see where the grass burns??? ️

 

[pc1966]

If you have one of those circuit tracers / fuse finder things you could attach it to one and and a spike in the soil and see what the probe finds as you go round?

 

[Jim_e_Jib]

I seem to remember Lucien describing a method he used that involved sending a signal down the cable and measuring the reflection that came back from the break. Something to do with using a CRT monitor to show the timing difference between the two and then calculating the distance to the break.

Time to pop to Radio Rentals for a 14" CRT...

 

[littlespark]

I seem to remember Lucien describing a method he used that involved sending a signal down the cable and measuring the reflection that came back from the break. Something to do with using a CRT monitor to show the timing difference between the two and then calculating the distance to the break.

Time to pop to Radio Rentals for a 14" CRT...

got my old childhood one in the attic, actually. Why ive carried it through 5 house moves in the last 30 years, i'll never know

 

[Jim_e_Jib]

Here it is:

Lucien's Heath-Robinson cable break location trick

I mentioned on another thread about using a computer and VGA monitor as a kind of Heath-Robinson TDR setup to find a break in a run of cable. Here's the promised demo. The hacked VGA test cable has a pair of flying leads connected in parallel with the green channel coax: Connected to the...

www.electriciansforums.net

It's lovely that all these gems of wisdom are preserved here

 

[pirate]

Send your wife to guide a proper mower round the lawn?
Tin hat on!

Seriously, use a cable tracer and follow the cable 'til it loses signal...

 

[mainline]

My friend has got one of those robot lawnmowers that automatically goes out once a day and runs around the grass.

There is a single core guide wire buried around the perimeter of the lawn that must carry a signal that the mower senses and knows not to cross…

This wire has a break in it somewhere.


Is there an easy trick, or tool that can be used to find out how far along the wire the break is…. Or is it likely non repairable and needs replaced?


He’s already tried a continuity test with a simple multimeter, which showed an open circuit between the two ends…. But that might just be the lack of capability of a simple meter.

I could shove main voltage down it and see where the grass burns??? ️

Use an AM radio.

 

[littlespark]

Use an AM radio.

Im going to give this a go. Seems straightforward enough.

Then I’ll look for the other video she mentions at the end on how to repair.
I was thinking through crimp