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sena smh10 bluetooth usb not charging blown ferrite bead

elmer thud

New Member
hi everbody first time on here i have a sena bluetooth helmet intercom unit its battery went flat and will not chargewith the usb cable,
upon inspection and taken to a electronics shop i was told what i already knew that the FB1 ferrite bead has blown and they want an extortionate amount to replace it,
now my qustion is and any replies and info is much appreciated
can anybody tell me the values of the ferrite bead as i would like to try and replace it my self it measures 2mm x 1.2 the unit charges from a usb cable 12v 1a unit at the rate of 5v 2.1a i am quite capable of doing this asi regulary repair honda goldwing electronics so can use a soldering iron i have some 0805 beads 600ohm will these do the job many thanks elmer thudB9E38939-5CB3-4BAA-B1DA-2102890B07A1.jpeg
 
Last edited:

JimB

Super Moderator
Most Helpful Member
It looks as though the ferrite bead is part of a filter (in conjunction with C3) to remove noise from what looks to be a power line.

Before agonising over what value to replace it with, try removing it and replacing it with a short wire.
Then you can apply power and see if the thing works.
If it does, then worry about the noise filtering bead.

JimB
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Well ferrite beads obviously don't 'blow', and I would suggest it's probably NOT a ferrite bead but is actually a fuse on the incoming USB supply.

Assuming something made it blow?, shorting it out might not be a good idea - but at least the smoke might give you a clue where the fault is?
 

JimB

Super Moderator
Most Helpful Member
Well ferrite beads obviously don't 'blow', and I would suggest it's probably NOT a ferrite bead but is....
I was thinking more in terms of a little "chip inductor" than a conventional ferrite bead.

Indeed blowing a typical ferrite bead would be an interesting exercise. (Wear safety glasses!).

But a chip inductor could be sent on its way to silicon heaven by a 100mA or so.

JimB
 

elmer thud

New Member
I was thinking more in terms of a little "chip inductor" than a conventional ferrite bead.

Indeed blowing a typical ferrite bead would be an interesting exercise. (Wear safety glasses!).

But a chip inductor could be sent on its way to silicon heaven by a 100mA or so.

JimB
hi jimB
i will remove the bead tomorrow and see what happens and message you let you know so what does the FB1 stand for on the board ??
 

elmer thud

New Member
just had another though there is another one of these components on the board it has a board location of FB2 on the board next to it i will post a photo after of this
 

elmer thud

New Member
I have taken the bead off the board and soldered a piece of wire on to board. I now have the battery charging. But it still will not power off it ( it is in a state of ON ) any ideas where I should be looking ? HELP
 

gophert

Well-Known Member
Most Helpful Member
FB typically stands for Ferrite Bead, not "Fuse, Blown".

measure the DC resistance and, if possible, the inductance Of one ore more of the other comparable parts.

they should be available for $1 each or less.


finally, look closely at your soldering. Your wire appears to be touching an adjacent resistor.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
FB typically stands for Ferrite Bead
Notice 'typically', which is the most relevant word - it could be anything, and FB isn't any kind of standard.

Buy even assuming it IS a ferrite bead, pretty pointless trying to measure it's resistance as a ferrite bead is simply slipped over a piece of straight wire.

I'm even dubious about the possibility of a SM ferrite bead?, as a ferrite bead isn't even an electrical component (it's just a bead, like in a necklace) - the device in question 'may' be a low value inductor, but it's almost certainly never going to fail or blow anyway.

I would still suggest it's a fuse on the incoming 5V, and FB stands for 'Fast Blow'.

However, the OP has done a truely horrible job soldering the largest piece of wire he could find across it :D Far easier to just stick a blob of solder across it.
 

gophert

Well-Known Member
Most Helpful Member
However, the OP has done a truely horrible job soldering the largest piece of wire he could find across it :D Far easier to just stick a blob of solder across it.
I took a minute to think about a diplomatic way to tell him his soldering instructor could use a refresher lesson before he teaches anyone else to solder like that. Eventually I decided to say nothing because someone with better/kinder people skills would come along and point out his skill deficit.

I agree that the bead doing virtually nothing except conducting (it may only be suppressing EMI emissions). I just don't know why it would fail. As my Professor from India used to say, "verdy, verdy veerd."
 

JimB

Super Moderator
Most Helpful Member
Trying to be a bit more diplomatic about this, when I said to replace the "FB" with a short wire, I meant something like this...

Wire Jumper.JPG

... where there is a 30AWG Kynar wire jumper in place of C6, or even just a simple bare 30AWG wire layed across the C6 position.

Also, for the Ferrite Bead, I assumed that the original was something like the chip inductor at position L1 on this board.

And before anyone comments, R3 is deliberately "tombstoned" for a reason.

JimB
 

JimB

Super Moderator
Most Helpful Member
Is it a controller for a pizza oven?
I have no idea where that thought came from, but the answer is no, it is part of an AD8307 evaluation board.

JimB
 

JimB

Super Moderator
Most Helpful Member

elmer thud

New Member
Ok ok lads come on this is my thread. Ok so I know it ain’t pretty soldering at the moment but it has done what I wanted it to do. And I’ll make a prettier job next time ok. The battery is now charging I have managed to put it on to my lap top and update it with the usb cable. So I have it charging but the headset will not turn off has anyone know what I should be looking for for this issue
 

gophert

Well-Known Member
Most Helpful Member
possibly a short from Your jumper to a data line that keeps the headphone on.

834FA751-D35D-4490-AE84-6C89855815DB.jpeg
 

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