Hi, i want to know what is this white rectangle element which is obiovusly burned this element is in the old electric fense. The problem is when the electric fense is warmed up, frekvency of shocking is very fast (and shock is almost unfeelable)...

Sorry about my english and thanks for all your responses!

Urbanre

 

It's a ceramic wirewound resistor but to find its value you need to see if you can read any numbers on it.

 

Obviously it's been running very hot.
But it may not be the problem, as whatever is feeding the resistor could have failed, causing a high current.

Post a clear picture of both sides of the board.

 

I doubt that the resistor is bad.

 

Hello,

Somehow the resistor got so hot that the PCB got the burn marks.
You might want to check if this is "normal".
When it is "normal" you might want to keep some more distance between the resistor and PCB.
This can be done using ceramic beads on the leads of the resistor:
https://www.ebay.com/itm/ONE-HUNDRE...OCOUPLE-FISH-SPINES-BEADS-No-21-/291768973335
(the leads will need to be longer for this).

Bertus

 

Thank you for all respondes. Here are some more photos of this "machine".. As i sad, at the begining it works fine (shock every second), but after some time (an hour or so) freekvency of shocking is very high (app. 3x normal). Thanks for all your help!!

 

You've got a string of MOVs damaged as seen in pic #7 above. This would probably explain your symtoms.

 

The resistor is on the Primary side of the transformer, being pulsed by the Thyristor. The output goes to a set of Movs to clamp the output, that are all cracked, that will be the cause of the excess current drain on the transformer.

 

The resistor is on the Primary side of the transformer, being pulsed by the Thyristor. The output goes to a set of Movs to clamp the output, that are all cracked, that will be the cause of the excess current drain on the transformer.

Do you think i should also replace ceramic resistor? If so, how can i know which one should i buy, because there is no value printed on it.. thank you very much!!

 

You need to desolder one end and measure it with a Dvm to see what resistance it is. Compare it with another on the pcb to see if is similar.

 

As it is wirewound then most often it will either be close to the correct value or open circuit.

 

Do you think i should also replace ceramic resistor? If so, how can i know which one should i buy, because there is no value printed on it.. thank you very much!!

If there is continuity on the resistor, there probably is no reason to replace it. Getting hot is what they do.

 

If this thread is still active, I suggest adding extensions to the leads of the R2 resistor so that it stands farther from the board. And yes, the varistors are damaged, I am not sure just why. Pulsing much to fast will cause the current limiting resistor R2, to overheat. AND, that is a quite strange fence charger.