Electric Fence Charger Repaired

[maybenever]

FYI
After a verrrry hard lighting strike, my fence charger was the only thing not working. It's a Zareba, model A20ML. The lighting killed the neutral side of the 120v outlet and took out the 750ohm 5w resistor that is inline with the 120v power supply circuit. (the little white bricks in the photo). Replaced both resistors (and the outlet) and it's back working good as ever, keeping my horses safely tucked in the field.

[Toasty]

Re: Electric Fence Charger Repaired

I would replace the MOV (blue disc) also. That probably fired and popped the resistor. Every time that MOV "works" it looses some of its ability to protect.

Toast

[maybenever]

Re: Electric Fence Charger Repaired

That MOV has not one marking on it. What part does it play in the circuit?

[maybenever]

Re: Electric Fence Charger Repaired

A little time of googleing, I answered my own question.
But again, with no markings, how would I get a replacement part? Anyway to check the ability of this MOV for voltage protection?

[Toasty]

Re: Electric Fence Charger Repaired

The markings are there, just may be -very- light and require a microscope (lol) to see. I've reverted to a jeweler's loupe and magnifying glasses for these.

Its part in the circuit is to do exactly what it did, clamps down the voltage spike and in this case opened the circuit. It -is- right across those resistors.

Do you have the original resistors? I thought that they would be the fusible type instead of just regular ceramics.

Toast

[maybenever]

Re: Electric Fence Charger Repaired

I've got the original ones. They are marked, RCD PW54WW 750R J V9-381.
I looked on the MOV with a magnifying glass, no mark, no impressions, nothing. I never could find a schematic on this board.

[Toasty]

Re: Electric Fence Charger Repaired

Then I guess I'm beating a dead horse...

Leave well enough alone and be happy it's working.

Good Job!

[maybenever]

Re: Electric Fence Charger Repaired

I appreciate all the help. It only takes a few minutes to get to this board. It's worth taking out that MOV and checking it.
I'm a newbie at all this stuff and trying very hard to learn, at least some basics. I read post on this website all the time, you people do a great job (with great patience I might add) to help one another and us dummies.
I only started this thread to maybe help someone else (dummie like me) that might have this happen to them. I know to yall it's a very simple circuit, but to me, I've learned something new. I guess it'll all add up some day. So again, THANKS, and keep up the good work.

[everell]

Re: Electric Fence Charger Repaired

I had a friend who tested his electric fence by peeing on it. I don't recommend it........

[maybenever]

Re: Electric Fence Charger Repaired

Not my first choice, but if had a drunk buddy, maybe I could talk him in to testing that way.

[maybenever]

Re: Electric Fence Charger Repaired

The markings are there, just may be -very- light and require a microscope (lol) to see. I've reverted to a jeweler's loupe and magnifying glasses for these.
Toast

You were right again. I took it apart again and with a very bright light and an extra strong magnifying glass, found SAS 241 KD14 MOV. Of course, could't find local, but one is on the way. They dunked this PCB in varinish about 10 times I guess, it makes seeing and checking components difficult.
Thanks again Toasty for the tip and the lesson.

[Toasty]

Re: Electric Fence Charger Repaired

Excellent! Where did you obtain the replacement from?

The "varnish" is a conformal coating because these are typically outdoors where moisture and electricity don't mix well. See post #9 above.....

[maybenever]

Re: Electric Fence Charger Repaired

They are NTE 541V15, coming from Parts Express.
They also had those 750 ohm 5w resistors for .29 cents, so I got a few of those for stock.

[Toasty]

Re: Electric Fence Charger Repaired

Can't find that NTE number anywhere.

Here is one from DigiKey: http://search.digikey.com/scripts/Dk...me=495-1416-ND

[maybenever]

Re: Electric Fence Charger Repaired

My bad, it was NTE 524V15.
Got CRS, can't remember stuff.