Resistor2 by CrapBag posted 26 Jul 2023 at 18:39 If possible could someone help here please, its not a great photo plus its not much better to look at in the flesh. As far as I can tell its brown black yellow (100k?) but the tolerance band is unclear, I'm thinking its gold. The resistor measures approx. 5mm across so its quite a big resistor. Its from a 12v battery electric fence, seemingly on the output, there is two of them and one has two holes blown in it and the other has one so they are both knackered. I have a feeling it they may well blow again but if its cheap enough to chuck a couple in and see what happens then I'm willing to give it a go.
So these would do, it states they are about 5mm across too https://www.ebay.co.uk/itm/304167313544?hash=item46d1c8e088:g:lSAAAOSwQT9hVYrp&amdata=enc:AQAIAAAAwEvmwBJWGd498NTqE0IQvDIKZ939JEeiVib+7jyqqJyE14f+oAvHQtv9KCwtMsl0Ne/R8k3dRIqOBwFTOS0QZ1XEOZO1WUk6a2yKpZnN4tIuo/pt3xKv+BJKSk8MDZlwYWjkA67LQRHtg6g14KsWbh6949Vakly3R+fwLYw6iV9GTMU+zFbQbTwv5A3vmmeyqAHSaFpEaBEyac9UmHd3093x4B2MI706XqEwyyfIqrWBV5RGx/ODdgnEVMv01QvaUw==|tkp:Bk9SR6qItrOyYg
I think those would be fine, but ideally you'd like something rated for the high voltage on the output side of a fencing energiser (not essential as most small energisers use standard resistors I think). I'm currently looking into one of our energisers that has failed after it was accidently connected to another unit and lost the fight and I think its some of the surface mount resistors that have died. All resistors on the input side appear to be film resistors and the output side are surface mount ones with higher power ratings. The unit I'm fixing (optimistic) is an 18 Joule mains unit and looking at a few old Gallagher 12V, 0.3 joule units I have here I can confirm the resistors on the output side are simple film ones.
Its a Shire 12V, 8500V, 0.6 joule unit. Does that mean the ones I've linked aren't rated for the high voltage, as they are the same physical size or is about what they are made of?
They are rated for 2W, however this will be constant and the output from an energiser isn't and I have no ideal how to calculate the right rating for a resistor in these circumstances. I can't tell what ratings the resistors in my small energisers are but in the 18J mains unit they are 25 - 45W attached in series. Ultimately I'd go with those and see if the unit works with them, if it does then great and they are cheap to change again, I would expect them to last a good while or fail immediately. If the unit doesn't work after changing the resistors then check to see if they have failed again before looking for faults elsewhere.
