Repairing Electronics (specifically an electric fence energiser)

[Mark1978]

So our electric fence energiser has been slowly giving up the ghost over the last few months and we finally replaced it with a new one a couple of weeks ago. However, I'd like to see if i can repair the busted one so that i can use it on my electric chicken mesh fence.

I dont know too much about electronics, but do have a standard multimeter that i could possibly use for testing. I'm guessing its either going to be the big capacitor jobbie, or the transformer at the top which is dead. My question is, how would i go about testing these parts to see which, if any, is the culprit. Could be the board i guess, but my hunch is the capacitor. Any ideas would be gratefully recieved.

 

[classic33]

So our electric fence energiser has been slowly giving up the ghost over the last few months and we finally replaced it with a new one a couple of weeks ago. However, I'd like to see if i can repair the busted one so that i can use it on my electric chicken mesh fence.

I dont know too much about electronics, but do have a standard multimeter that i could possibly use for testing. I'm guessing its either going to be the big capacitor jobbie, or the transformer at the top which is dead. My question is, how would i go about testing these parts to see which, if any, is the culprit. Could be the board i guess, but my hunch is the capacitor. Any ideas would be gratefully recieved.

Have a gander at http://www.doityourself.com/stry/how-to-repair-an-electric-fence-energizer & http://www.ehow.com/how_2096914_repair-electric-fence.html

 

[accountantpete]

The AC current goes into the transformer as 240 and exits as a reduced voltage so you need to test the exit AC voltage on your multimeter to make sure the transformer is working (black to black and red to red).

Presumably the AC out of the transformer then goes through a rectifier (including another Capacitor) to provide a DC supply. I would look for anything that has burnt or expanded and then try tracing the current back until you get a reading on the DC voltage on your Multimeter (keep multimeter black pole on the ground of the transformer and test with the red).

 

[Leaway2]

I would be surprised if 240V was involved. My guess (and I have not looked this up) is that a battery feeds the unit, which chops the voltage, this will be fed into a (step up) transformer. The output of this will be a relatively high voltage ,low current, to give a shock.
I doubt if the transfomer will have blown. The capacitor may have broken down, but I would plump for the transistor that does the switching.

Just Googled and some are mains powered, so what do I know, Ill shut up!

 

[classic33]

I would be surprised if 240V was involved. My guess (and I have not looked this up) is that a battery feeds the unit, which chops the voltage, this will be fed into a (step up) transformer. The output of this will be a relatively high voltage ,low currant, to give a shock.
I doubt if the transfomer will have blown. The capacitor may have broken down, but I would plump for the transistor that does the switching.

Some are mains, others battery powered.

You may damage just the mutimeter if you're lucky.
http://www.hallman.ca/troubles.htm

 

[Mark1978]

Have a gander at http://www.doityourself.com/stry/how-to-repair-an-electric-fence-energizer & http://www.ehow.com/how_2096914_repair-electric-fence.html

Yeah, they kind of just show how to diagnose an electric fence fault, which includes a replacement of the energiser if faulty Its definitely a fault internally as the new energiser is pumping out 8kv for the length of the fence, whereas the old one was struggling to do 1kv over the points on the energiser itself!

It's a mains powered one. Interestingly, the red wires from the transformer are what go directly to the energiser points (ie, one is for earthing rod, one is for live on the fence). There are two other black wires from the transformer. Not sure where the black wires go as i haven't attempted to pull the board out to trace them. I'll pull the board out later and see if there's anything obviously blown on there too.

You may damage just the mutimeter if you're lucky.
http://www.hallman.ca/troubles.htm

I wouldnt use a multimeter across the energiser points, ive got a specific tester for that kind of short, high voltage testing. Was just wondering if there was anything internal to the unit that i could test with a standard multimeter, such as if the capacitor was faulty (but i think there are specific tools for testing capacitors).

 

[classic33]

Yeah, they kind of just show how to diagnose an electric fence fault, which includes a replacement of the energiser if faulty Its definitely a fault internally as the new energiser is pumping out 8kv for the length of the fence, whereas the old one was struggling to do 1kv over the points on the energiser itself!

It's a mains powered one. Interestingly, the red wires from the transformer are what go directly to the energiser points (ie, one is for earthing rod, one is for live on the fence). There are two other black wires from the transformer. Not sure where the black wires go as i haven't attempted to pull the board out to trace them. I'll pull the board out later and see if there's anything obviously blown on there too.




I wouldnt use a multimeter across the energiser points, ive got a specific tester for that kind of short, high voltage testing. Was just wondering if there was anything internal to the unit that i could test with a standard multimeter, such as if the capacitor was faulty (but i think there are specific tools for testing capacitors).

http://www.electricaltechnology.org/2013/06/how-to-check-capacitor-with-digital.html

Might sound daft, but any smell/taste that doesn't seem right?

 

[Mark1978]

found this which is quite helpful.

http://www.ozvalveamps.org/repairs/fencer.htm

 

[twentysix by twentyfive]

It's basically a trace through the unit from input to output to see where the fault is. Check for Volts as you go

 

[Smurfy]

Yeah, they kind of just show how to diagnose an electric fence fault, which includes a replacement of the energiser if faulty Its definitely a fault internally as the new energiser is pumping out 8kv for the length of the fence, whereas the old one was struggling to do 1kv over the points on the energiser itself!

It's a mains powered one. Interestingly, the red wires from the transformer are what go directly to the energiser points (ie, one is for earthing rod, one is for live on the fence). There are two other black wires from the transformer. Not sure where the black wires go as i haven't attempted to pull the board out to trace them. I'll pull the board out later and see if there's anything obviously blown on there too.




I wouldnt use a multimeter across the energiser points, ive got a specific tester for that kind of short, high voltage testing. Was just wondering if there was anything internal to the unit that i could test with a standard multimeter, such as if the capacitor was faulty (but i think there are specific tools for testing capacitors).

Are you sure it's supposed to push out anywhere near 8kV? The marking on the capacitor is 1200V, which would allow a margin over 1kV output.

 

[classic33]

Is that a blackened diode across the outputs?

 

[Mark1978]

Are you sure it's supposed to push out anywhere near 8kV? The marking on the capacitor is 1200V, which would allow a margin over 1kV output.

I dont do electrics, but im guessing that the transformer steps that voltage up to the 8kv across the points, reducing the current to a safe level for zapping.

 

[Mark1978]

Is that a blackened diode across the outputs?

Nah, there are no visible blackened bits. Theres a bit of metal that isnt looking too healthy on the right output, but it doesnt connect to anything

 

[Mark1978]

Just put an ohm meter across the capacitor and it reads 0, so i guess that means it's shorted out and knackered. I'll see if i can find a replacement.

 

[classic33]

Nah, there are no visible blackened bits. Theres a bit of metal that isnt looking too healthy on the right output, but it doesnt connect to anything

What's the piece "circled" between the outlets?