Mystery Component Challange

[biker1234]

A challenge for you!

My CDI unit for my motorbike has burnt out. I'm trying to discover the identity of component 'V1' (in top centre of PCB in image link below), so maybe I could get a new one to solder on. In this picture it is intact, but on mine it has burnt to a crisp...nothing is left apart from a small black disk.

Any Sherlocks out there?

 

[Harald Kapp]

I guess there should have been a picture? I can see only a circle with a slanted line through it. Your image is probably on a server that is not accessible by us.
Tip: Go >advanced< and attach the image directly to your post.

It may also help if you post the type and/or part number of the CDI unit.

 

[eem2am]

what is a CDI unit...anyway, ill say it may well be a varistor, as its "V"1.

If it is , then you will have to solve whatever made it blow, not just replacing it

 

[biker1234]

Sorry heres the pic for you guru's out there. Thanks for quick reply!!!!

 

[shrtrnd]

Do you see any markings on the side of the device?
Could be a cap, a resonator, an encapsulated anything else.

 

[Arouse1973]

Varistor? Small one, posibly.
Thanks Adam

 

[biker1234]

I no nothing about electrics- but if it's a varistor would that make sense why that one melted and others were fine? It took the hit and shunted to ground? What type could replace it? The board is for the bin unless fixed so what's the harm in trying something and connecting up? Will only melt the board right?

 

[Arouse1973]

I no nothing about electrics- but if it's a varistor would that make sense why that one melted and others were fine? It took the hit and shunted to ground? What type could replace it? The board is for the bin unless fixed so what's the harm in trying something and connecting up? Will only melt the board right?

Yep.
Adam

 

[KJ6EAD]

The silkscreen marking reads C3, a capacitor.

 

[Arouse1973]

The silkscreen marking reads C3, a capacitor.

I think that's the one below it.
Thanks
Adam

 

[KJ6EAD]

You're right. It's a varistor.

Note to users: rotate your blurry images right side up so the board markings are readable.

 

[biker1234]

Ok, So the circuit board runs off a 12v 10A battery. Voltage goes up to around 16-18v when engine is running. What should I replace it with? A guess is fine.
Also someone said something about what caused it? meaning a short in the wiring before the board? I'll go hunting.
Thanks Einstein team!

 

[KJ6EAD]

I'd suspect the output transistors (Hitachi 2SD1976).

http://documentation.renesas.com/doc/products/transistor/e208918_2sd1976.pdf