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[vumphman]

I have just taken possession of a Kyosho Jetstream 800 ... my first electric boat ... bought ridiculously cheap on ebay.  It has a Le Mans 360 brushed engine and came with two battery packs ... one bearing "Ni-cd 1100 mAH 12v" and the other "Feima AA 900mAH 12v".   I charged up one of the packs, placed it in the boat, turned on ... and the motor started no problem.  As I increased the speed, the small blue "thingy" that was soldered between the + and - terminals on the motor went bang in a big way ... much smoke ... inside of the hull covered in what looks like white fibres ... but the engine still runs.  I assume that this "thingy" was somethng to do with engine noise suppression ... either a suppressor or something.  Can anyone confirm this?   and what should I be buying to replace it.

I work on the basis of the following equasion .....   Me + Electricity = total confusion

Regards ... Mal

[Tug-Kenny RIP]

The blue thingy is a capacitor.

No harm done.  Just unsolder or cut it from the motor terminals and replace it with a new one. The value in micro farads should be around 0.1. You may find a piece of the old one in the boat with a value written on it.

All it does is to suppress the sparking motor and stop it it interfering with the Receiver.

Hope this helps

ken

[vumphman]

Many thanks Ken, both for the speed of the reply and the information ... I found a bit of blue plastic and all I can decipher is "16v 47uF".  Just as well I enjoy learning curves !!!

[GG]

Mal,
Sounds like the original capacitor was the electrolytic type.  You appear to have found out why they are not recommended for use in our models!
Try to use a ceramic capacitor, ought to last a bit longer!
GlynnG

[vumphman]

Thanks Glynn ... I have just spoken on the phone with a chap called Malcolm at Cornwall Model Boats ... very friendly and helpful ... and didn't try to sell me anything (which means when I really do need something, I'll be giving him a call).  He has told me how to check if I need to replace it at all (looking for rudder servo twitter), so I'll start from that.

[malcolmfrary]

An electrolytic capacitor is usually a "one way" device - I assume that there is no reverse on this boat?  Electrolytics are generally useless at calming interference down because of the way they are constructed so at a guess yours had another job to do, probably something to do with stopping the motor sending damaging voltages back into the ESC.
Fit a 0.1 ceramic as Kenny suggested to calm RF interference, but look for a 47uF capacitor rated for 25 volts or greater.  The 16 volt one was probably on the limits of its operating tolerance on a nominal 12 volt supply and having to deal with the back EMF coming off the motor on top of that. (Sorry about the techno-babble).
The white fibres are probably metal foil (probably aluminium) and whatever was coated onto it to be the separator and the gunge that was the electrolyte.  Big ones are MUCH more exciting when they go off.

[vumphman]

Thanks for the info, Malcolm.  Correct ... there is no reverse on the boat, not after I replaced the original mechanical speed controller which was stuck in reverse only.  From the shape of the hull, I think it will go much better going in the direction the pointy bit.   At least ... I hope so !!!!!