Old Electric Fence Controller Stopped Cycling

Do you know the make & model/type of the "slow-cycle electric fence controller"?

Here is some reading material on the subject.

Electric fence - Wikipedia, the free encyclopedia

It is a UNICO Rocket Model 2-4-D Electric Fence Controller. Thanks for the link--it sounds like an internal switch may have failed.

You may download the manual here.

rocket manual pdf ebook download

Fence Charger | Electronics Forum | Electrical Engineering - EEWeb

I'm afraid those don't apply to this, but thanks.

I can't help you with the electronics but we used a similar fencer for our horses. If anything was touching the wire fence that the electricity would not deal with then it would continue to hum but not work. It could take care of grass; large weeds or branches touching it would cause it to stop. Try walking the fence line to check for debris.

anicholas, if you are an electronics man, you can study some of the circuits, in THIS link to get some idea on its working.

If its 50+ years old maybe its just time to buy a new one.

Alas, that might be the best thing to do.

Being made in the 60's it should be a fairly simple circuit. A transformer & a timer circuit with not much else, try taking some pictures of the insides of the controller & show us what's in there. If you can get detailed pics of both sides of the board & components there might be a slim chance of us seeing & identifying some thing to repair. I have tried some searches but have not found any circuit diagrams for it as yet

If you used to hear an audible "CLICK" when it cycled, it probably has a flasher,similar to an old mechanical automotive flasher.They will not interchange, however.You can disassemble the can and un stick the contacts if they have fused.

Another type uses a neon bulb to generate the pulse.IF the bulb blows,it will not pulse,but it will hum.Check the resistor in series with the bulb(indicator light).It is usually a fairly high value, so read the bands for resistance.It is not critical, but should be within about 5 to 10 % tolerance.

These are two types from that era that I am familiar with.

There are plenty of DIY chargers on line with schematics.

Google it.

'...The controller appears to be a rather simple device with only an external fuses and a capacitor, but I've been advised by one source that replacement of either of these items will not likely correct this problem.....'

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I'm a little suspicious of the one source by which you were advised.

Did the source inspect either the fuse or the capacitor?

Did the source offer any hypothesis on what might correct the problem?

Does this source happen to either....

1. have tried unsuccessfully to remedy a similar problem, or...

2. hope to sell you a new unit?

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I suspect the capacitor is bad. If it is electrolytic, I would wager money that it has gone bad.

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Luckily, both fuse and capacitors are often relatively simple to check.

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A simple visual inspection is often sufficient to confirm a fuse is good, or that a capacitor is bad.

A fuse is probably just fine if it is simply appears not to be burnt out.

Capacitors vary somewhat by type....common failures in electrolytic capacitors are often accompanied by swelling, rupture, or leakage of fluid. Signs of arcing, burning or other trauma are bad signs for any type of capacitor really.

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So, what does the inside look like? (remember that things like capacitors can hold charge for some time, so be careful opening this and any electric device) Maybe snap a few photos and post them so we can help?

That one source:

From: cwilliams@AESOP.Rutgers.edu
To: ANich60544@aol.com
CC: esc@AESOP.Rutgers.edu, gladney@AESOP.Rutgers.edu
Sent: 10/24/2012 4:18:31 P.M. Eastern Daylight Time
Subj: RE: Ask the Expert/Electric Fence

Hello Allan,

I consulted with our Rutgers Farm staff who has expertise in this area and here is what we came up with:

"He should turn it off immediately. If he really has a charger/energizer made for an electric fence it will pulsate the current which allows anyone to let go when there is no charge. Without the pulsating charge he will end up electrocuting things - you get "stuck" to the electric source. I doubt it is the capacitor or a fuse. The capacitor is what increases the voltage - electric fences can be up to 12,000 volts from a 110 volt outlet. If the fuses are blown he would not have electricity coming out. My thought is that if it is truly a charger/energizer then the energizer has gone bad and all he has now is an A/C charger. With the continuous charge a fire could also start if weeds come in contact with it."

Hope this helps.

Dr. Carey Williams

======================================================

Carey A. Williams, Ph.D.

Extension Specialist in Equine Management

Rutgers, the State University of New Jersey

84 Lipman Dr., 213E Bartlett Hall

New Brunswick, NJ 08901

PH: 848-932-5529

FX: 732-932-6996

www.esc.rutgers.edu

======================================================

From: ANich60544@aol.com [mailto:ANich60544@aol.com]
Sent: Monday, October 22, 2012 8:14 PM
To: cwilliams@AESOP.Rutgers.edu
Cc: esc@AESOP.Rutgers.edu; gladney@AESOP.Rutgers.edu
Subject: Ask the Expert/Electric Fence

Dear Dr. Williams,

I have rigged an electric fence using an old (circa 1960) charger/energizer which has recently stopped cycling but remains energized. It is a simple device with what appears to be a capacitor and a couple of fuses. If any of these are defective, might that be causing the lack of cycling, or is this evidence of something worse? Thank you for your help.

Regards,

Allan W. Nicholas

3628 Manly Farm Rd., Wake Forest, NC 27587

919-266-7504; cell--919-606-4784

anich60544@aol.com

This unit is riveted together and is thus not amenable to disassembly. BTW, upon further checking, the 2 one amp fuses present are OK; the capacitor is silver, round and has 3 pins. I will probably need to search out a farm supply store around here to locate a replacement. Actual date of manufacture appears to be 2/72.

Thanks everyone for all the great responses.

certainly seems like a trustworthy source.

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Does the capacitor appear swollen, split, leaking?

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I'm not familiar with the electrical component terminology 'the energizer'.... anyone know what this refers to? Inductor perhaps?

There is no visible damage to the capacitor. The only thing which may be a problem is that the base of the capacitor with the 3 pins turns freely in the silver body of the capacitor. I don't know whether this is normal or not.

That is not normal for any capacitor I know. Capacitors are typically cheap and easy to order as per specifications on the side... the most important ones being:

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1.capacitance, in some division of a Farad, e.g., nF or uF.... this value needs to be the same.on a replacement

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2.type of current and number of poles....and general form.

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3. Voltage a replacement should be rated to at least the same as what it is replacing. Higher ratings on the replacement will work as well with no problems.

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If you Google the numbers on the side you'll probably find an exact replacement.

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-If a faulty capacitor is not allowing voltage to climb sufficiently, AND that is causing the unit not to undergo regular discharge, that might be the only problem.

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-It is entirely possible that the switch or discharge mechanism used in this device is also damaged, perhaps as a result or for the same reason as the possible faulty capacitor.

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-A third scenario to consider is that I might just be unfamiliar with this type of capacitor that has a sliding jacket of some sort...and the capacitor is fine. The thing to do would be to remove it before ordering a new one, since you would need to remove it anyway to replace it. You can put a small charge on it from a 12V battery and use a multimeter to see it it can hold the charge for even a short time. If the capacitor is damaged it is unlikely to hold any significant charge for long.

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I hope at least some of that is helpful.

I don't think that is the capacitor but it may be the problem , most farm stores sell that unit that plugs into the side of the charger some are two pin , I think it regulates the pulse .

It might also be a pendulum type, where a metal arm swings thru a coil, making and breaking the circuit. If the arm sticks, no output.

If it was mine, I would use a more modern (if you can call a 555 circuit modern!!) simple circuit to replace the 60's stuff, but reusing the still good HV transformer and the container etc..

Check here for many different circuits:-

Electric fence circuits

First problem we looked for if not cycling is a short to ground along the wire.

Other then that the only other thing I know is they are rude awaking when you miss judge and walk into one in the dark.

Oh one other thing most dogs don't make it if the cock their leg on a support pole and hit the wire with the stream.

The "flasher" I referred to is usually in a metal can that plugs in at the front of the unit.

Some have 2 wire, some have 4 wires.

If the unit is not available at your local farm supply, a work around is this:

Install a 40 watt flourescent starter in series with the hot side of the supply line.

They can generally handle up to 60 watts, which should be sufficient for the charger.

Very simple and easy to replace when it burns out.The flash will not be as precise as with the original, but it will work just fine.

I suggest putting an MOV across the line for protection from surges.A GE V130 LA (I think that is the right number, working from memory,here.Been a long time.)should be about right.Put it in after the fuses.It responds much faster than a fuse,but is a one-shot deal so when it goes, it "Crowbars" the circuit, and the fuses are secondary for overload or short circuit only.

The rivets can be drilled out and replaced with screws.Some of the older units had non-tamper screws that looks like an hour glass.These can be removed by finding the proper sized drill bit, and running it in reverse, under lots of downward pressure.

Hope this helps.

Thanks for this; will keep it in mind.

Greetings.

I have had fence zappers before and one of the things that was a replacement was the capacitor.

If yours is soldered in desolder it and check it with an ohm meter.

If it is the capacitor you can usually get one at a electronics supply store and solder it in.

The old simple ones seem to be the most dependable. I still have one that is over 35 years old.

I feel that it would be a good idea if you instructed the OP on how to test the capacitor. Most (even good meters) don't have a capacitor range, even today......

There is a way with a normal meter, but its not very accurate......more of a quick field test to my mind that will not find all problems....

Greetings.

If you unsolder the capacitor or have one that is a plug in like some of the older ones.

Take an ohm meter (an analog meter with a needle is the best for this test) and zero the meter on high resistance (20,000 ohms per volt if you have it). Place the leads on both sides of the capacitor. If you read continuity the capacitor is shorted.

If you don't read continuity reverse the leads. You should see the meter needle move and then come back to zero. If you see the last then the capacitor is hookie dookie.

Have a Great Day.

Well put, but it really only says its not shorted, not that its value is what it should be....also this does not test the capacitor under high voltage, which may also be applied to it in such a circuit.....

I was hoping that you knew something I didn't, but many thanks anyway.....

I did the same as a quick check myself years ago, but for the last 15 years or so, as meters got cheaper, I now have two that will read both capacity and inductance as well as frequency to a degree. But I still cannot test at a high voltage either, at least not safely!!!

Ironic that we are discussing fence chargers,because I just received one in need of repair.It is at least 25 years old.It has a timer circuit with a couple of capacitors and an SCR,the usual bunch of resistors, and a few diodes.I will not go into the functions of each here, but the problem on this one was the SCR.It was a S6008L-ND,cost about $2 bucks from Digikey.A hint for VERY long fences, or VERY dry ground: RG6 Coax makes a nice high voltage capacitor.Make a coil of the coax at some point mid way of the fence, and connect the center to the fence, and the shield to ground.You will get between 17 and 18 Pf per foot.Doesn't sound like much, but it will bite !A couple of these placed strategically will keep the power up.
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Thanks to all who have contributed to the discussion of this issue. After conferring with Agri Supply Co. (a large ag supply company in the southeast US), the problem was finally solved by procuring a replacement for the so-called "3 prong capacitor". It is actually called a Three Prong Weed Chopper Replacement Interrupter Switch for Weed Chopper Style Energizers (Dare Products, Inc., Battle Creek, Michigan). The unit is now working fine with the usual approximate 1 second cycling.