Thunderbird M-100 Electric fence controller

[b.james]

I have a blown up one in which both of the large brown caps have blown and there is no identification written on them that I can see.

I would like to replace them but being high voltage cannot guess what their values would be . Anybody know?

 

[alec_t]

Can you post a sharper-focus picture of the board? Can't read the markings, especially on that big chunky square component (which I'm guessing is a bridge rectifier which has failed?). Any chance of a schematic?

 

[b.james]

No schematic - I rather hoped someone here might have one .
Tried another camera but not any better.
Black boxy thing has only 2 soldered connections not 4

 

[debe]

Use Macro feature on the camera to get clear pictures.

 

[alec_t]

Tried another camera but not any better.

Eh? Even my grandkids' cheap cameras can do better than that .

 

[b.james]

Hmm must be the photographer then huh?

My cameras are Auction specials for $20 and the problem is more with the flash reflection.
Loading the pics to the computer can be an issue as each camera is on a different system and some are detected some not .

Add to that this sites ridiculous size restrictions for uploading and the resizing needed to comply gives me the shits with pictures so what you have is what you get . I took about another 10 but none any better.

Now , on more important stuff which is why I posted here,its been suggested to me that the caps are 2uF 630VDC, but they must be rated for pulse application. I might be better off to get a 4uF 400VAC motor run capacitor with push on terminals, and use 2 short thick ( 1.5mm) wires to connect them to the board. That way when it next fails ( after a year or two) I can just plug in a new 4uF capacitor.

So all is not lost yet by silly side issues trying to provoke a response

 

[b.james]

Use Macro feature on the camera to get clear pictures.

Really .. Gosh never thought of that !

 

[Tony Stewart]

You cant guess at design specs, but from my experience, I would find the exact colour and part in the same or better 350vac rating with the biggest value in plastic film.

My best choice with a quick look is this.

https://www.digikey.com/product-detail/en/940C8W2P5K-F/338-1150-ND/809443, its a lot bigger size but far more reliable then find the size of uF on the web.

 

[debe]

What you have found is probably ok. This is some pics of an electric fence battery powered. The capacitor used is a 2.2uF 250v_MKT. I use an old Nikon camera 4Mpixel, which was cheep cost me $5 in a garage sale, For this type of photos I use Macro & daylite shady area. If you use flash there is too mutch reflection. Using a 4mpix camera the pictures don't need to be re sized to post.

 

[b.james]

OK debe thanks I'll try the daylight approach

 

[Tony Stewart]

you can also use the same Philips part which is cheaper or the better quality part I suggested that wont blow up.

I recall the Polypropylene Panasonic ESR is 10x lower ESR and self healing

The MKT is Polyester is good but with more heat excitation under a fault is prone to detonation

edit....
just checked my PU choice is >100x better than the PE part from Philips

 

[b.james]

you can also use the same Philips part which is cheaper or the better quality part I suggested that wont blow up.

I recall the Polypropylene Panasonic ESR is 10x lower ESR and self healing

The MKT is Polyester is good but with more heat excitation under a fault is prone to detonation

edit....
just checked my PU choice is >100x better than the PE part from Philips

What are the following please
ESR
MKT
PU
PE
self healing ?

The normal rule is if you want to use these,expand them fully at first use then use the mnemonic thereafter

 

[b.james]

Can you post a sharper-focus picture of the board? Can't read the markings, especially on that big chunky square component (which I'm guessing is a bridge rectifier which has failed?). Any chance of a schematic?
Eh? Even my grandkids' cheap cameras can do better than that .

Hey I have cataracts on both eyes and got one fixed yesterday . Looking at the photo its actually quite clear and sharp now . Had your eyes checked lately?
Its simply stunning how the eyesight detail and contrasts go as cataracts develop , you don't notice them creeping up but boy do you notice it when they are fixed.

 

[Tony Stewart]

What are the following please

ESR = Effective Series Resistance, the critical parameter, thats causes self heating, if ignored causes the cap to blow up like yours.
MKT=metallized plastic high K with terminals can be PE or PU
PU = PolyUrethane a better self healing lower ESR, lower leakage cap
PE=PolyEthylene and lower cost low ESR cap
self healing , if hotspot fuses a strip of metal conductors in a short, the capacitance reduces, the metal fuses open, the plastic cools and heals. Like having many small caps in parallel and one defective cap fuses open and the bulk surbives

If you had read my datasheet it would have explained most of this. Sorry. This takes a longtime.