Page 1 of 1

Exploding Junction Box

Posted: Mon Sep 25, 2006 2:23 am
by superfly108
basicly im fiddeling with my engine timing after fitting a new tensioner blade, going to test that i did it right, and press the starter, i get the same syptoms as a flat battery, jumping needles clicking noise, so i goto turn the ignition off and it stays on oil light still on, i put my mates battery in, and still nothing same problems, we notice the clicking is coming from the junction box, so i fiddle and notice a hole in the back of it, that smells of burning, i brake it open to find one of the components inside (resistor) im guessing has superheated and melted itself its near by resistor and the board and casing, so why the feck would this happen, it has rained lightly on the bike without cover, no seat on or anything, i did notice the connections looked a little wet
ive got a mate sending hes old junction box to me, so gonna try that but i dont want that exploding either

any ideas?

Posted: Mon Sep 25, 2006 9:32 am
by masterofinsanity
sounds like its got wet and shorted but isn't the junction box a sealed unit?

Posted: Mon Sep 25, 2006 7:18 pm
by superfly108
heres some pictures of what the damage was

pictures

Image

and what it did to the casing

Image

Posted: Mon Sep 25, 2006 7:34 pm
by superfly108
and this is what blew on the diagram, the red section is the diodes that blew, and the blue one is the one i think blew, althoguh theres not enough left of the board to see
'
Image

Posted: Tue Sep 26, 2006 2:58 pm
by RedexRobB
Oooer mate, if it is the diodes that have gone then there must have been a short across somewhere thats reverse biased them, diodes will only take current in one direction. They will take it in the other direction but only upto a point, then they do what you can see there; they break down and destroy themselves.

TRY LOOKING HERE

Posted: Thu Sep 28, 2006 11:42 pm
by ernie
Hi, mate just had the same thing happen to me. While you have the plastics off have a look under the middle top engine mount under the fuel pump, you should see a think plastic pipe covering your wiring loom. chech this for any burns or hard plastic like it's been hot you may have to disconect your stand start, gear selector so that you can have more play in the loom.

They seem to rub under there and can burn through as they short out with water getting to it this can be a giraffe but I'm hopping after a couple of hours in my shed I should be back on the road this weekend

all the best and good luck :smt006