Hello,, can someone identify components in a Gallagher M4000 ?

[Joseph William McLintock]

Hi, i have a Gallagher M4000 electric fence energizer.. it has some unmarked components on the outlets, i think they are some sort of lightning bleed-offs... Gallagher are of no help. And i have found nobody who can help me yet.
I see the M4000 in USA, in Youtube,, is exactly the same borad,, but has non of theses componets installed..
pic of removed component ,approx 20mm x 7 mm

 

[dave9]

Shaped like resistors, have you measured for resistance? Has this board failed, why are you focusing on them?

 

[kellys_eye]

Potentially high value, high voltage bleed resistors. I have a load of boards with similar devices and, when measured, were found to be just resistors.....

 

[duke37]

Could you draw the circuit diagram?
The neon looks in pristine condition so the unit has not been used much.

They could be capacitors in a voltage doubler.

There is one, bottom right with a browm tummy. Overheated resistor?

 

[kellys_eye]

They could be capacitors in a voltage doubler.

You can see the smaller blue capacitors across the glass bead diodes that form the capacitive multiplier. I'd agree that one of those 'resistors?' is looking a bit stressed though.

 

[duke37]

I do not think that the diodes and capacitors are part of the voltage multiplier, since the capacitors are directly across the diodes, not in a ladder network. In the early days of the BY100, capacitors were used to equalise the voltages across the diodes. When the RAS310AF avalanch diodes came in this technique seemed to die.

Early fencers connected the fence directly to the transformer. More recent ones seem to rectify the pulse, perhaps to maintain a DC voltage on the very long fences. I think this is what these diode do. Do the five resistors at the bottom right go to the fence?

There is another line of diodes? at the top of the picture.

Does it work? If not I would measure the voltage on the discharge capacitor.

 

[davenn]

And i have found nobody who can help me yet

Just measure them !!

if you don't have a multimeter GET ONE …. you cant do electronics without one

 

[duke37]

If you bothered to draw a diagram and say if there is a problem, perhaps we could help.

You can get a chinese instrument cheaply which can measure resistors, capacitors, inductors and transistors. I bought one and made a little plywood box to house it.

 

[Joseph William McLintock]

Just measure them !!

if you don't have a multimeter GET ONE …. you cant do electronics without one

hello,,, the components are non-conductive.
Thats what makes me think, they only conduct at super high voltages from lighning..

 

[Joseph William McLintock]

If you bothered to draw a diagram and say if there is a problem, perhaps we could help.

You can get a chinese instrument cheaply which can measure resistors, capacitors, inductors and transistors. I bought one and made a little plywood box to house it.

mmmm. i have a high quality Fluke

 

[Joseph William McLintock]

Shaped like resistors, have you measured for resistance? Has this board failed, why are you focusing on them?

Yes,, there is no conductivity what so ever...
thats what makes me think they only conduct in super high voltage..
well, 2 of the components in question have been ruined,, and are conducting.. when removed, the unit is running fine.. but i want to restore the unit's lightning resistance back to original

 

[duke37]

mmmm. i have a high quality Fluke

So, what does it show?

Are the hills alive with the sound of bagpipes?

 

[Joseph William McLintock]

Could you draw the circuit diagram?
The neon looks in pristine condition so the unit has not been used much.

They could be capacitors in a voltage doubler.

There is one, bottom right with a browm tummy. Overheated resistor?

Yes,, the 2 are no good and i have removed them,, the rest seem to be ok,,
But... You say they are a resistor? That is what i first thought too,,, but i cannot get a reading on them,,,!
Either they are so high resistance, i cannot read on my mulitimeter,, or they are some other type of component[/QUOTE]

 

[Joseph William McLintock]

So, what does it show?

Are the hills alive with the sound of bagpipes?

No reading at all

 

[davenn]

Yes,, the 2 are no good and i have removed them,,

which 2 ?

the rest seem to be ok,,

which rest and what do you mean by OK ?

 

[kellys_eye]

A device that conducts when high voltage is applied is usually a 'spark gap' and those parts don't look like any I've ever seen.

If they are meant to bleed static voltages to ground then they could be very high resistance resistors (10MΩ or higher) but that doesn't mean they can't suffer from 'flashover'.

But, if you've got a Fluke then you should get an actual reading from the component......

 

[Joseph William McLintock]

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A device that conducts when high voltage is applied is usually a 'spark gap' and those parts don't look like any I've ever seen.

If they are meant to bleed static voltages to ground then they could be very high resistance resistors (10MΩ or higher) but that doesn't mean they can't suffer from 'flashover'.

But, if you've got a Fluke then you should get an actual reading from the component......

, i not sure.. i removed only one from the group, you can see in the pic,,, and tested it, and another form the other group,, and it had no reading at all,,, maybe i should try removing some others too,, and testing them,,, .. it would be good to know what they are,, Maybe they are some sore of MOV ?

 

[kellys_eye]

Show us an image of the device connected to your Fluke and the reading on the display.

What is the 'mustardy yellow' covering on the component? Can you scrape it off?

 

[duke37]

I have seen these components on other Gallagher fencers and have not been able to determine what they are. I bought a packet of what I thought were ceramic capacitors at a radio rally, they measured about 5pF so I do not know what they are.


There used to be a website put on by a UK government organisation showing how to erect a fence with an inductance. I have not seen it lately.

My brother used to have fencers damaged by lightning and I made an inductance, six turns of fence wire about 300mm diameter, spaced about 25mm mounted on a wooden cross. There were no more damaged fencers. Whether this was just coincidence I know not, but worth a try.

One Gallagher fencer had a PCB plugged in at right angles to another board. The current objected to going the long way round and sparked across the corner, producing ozone and rotting the plastic holding the transformer together. I soldered gently curved links across the contacts and used a twig to hold the transformer together. This seemed to work but the fencer made a very loud click. A better bodge would doubtless quieten it.

I could not find details of the M8000.

 

[Joseph William McLintock]

Potentially high value, high voltage bleed resistors. I have a load of boards with similar devices and, when measured, were found to be just resistors.....

ah ok, thanks,, that is what i first thought they are resistors... Did you get a reading ohm reading on them?