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Subject: Re: Recorder Hardware Question
From: Ryan Press (ryan+list_at_presslab.us)
Date: 2004-03-26


Andreas Stemmer said:
> I've got a broken recorder model here (old recorder 6GB). The broken
> part is a small SMD part, but I don't know what it is. I marked it on
> one of Phil's recorder photos from the rockbox homepage.
>
> http://home.vrweb.de/~andreas.stemmer/rec_iface_bottom.jpg
>
> The part is completely burnt, so there's no chance to identify it. If I
> follow the traces, I can see that it was connected in series between the
> center pin of the dc input and a zero ohm resistor which goes straightly
> to the mc34063a dc/dc converter.
> So what could it be? My first guess was that it was another zero ohm
> resistor, but that doesn't make sense because there are no other traces
> which have to be crossed. And we all know that the jukeboxes do not have
> any protecting diode. Some kind of fuse? Any ideas?
>
> I repaired it by bridging the crater with a diode and the recorder works
> well again, but I'm still wondering what it was.
>
> Andreas

Hi Andreas,

That component is a ferrite bead; an inductor of sorts. It is there to
attenuate the high frequency noise that comes in on the power wire. This
noise (if very bad) could cause the microprocessor to lock up or you may
hear something in the headphone output.

It is not really needed but here should be a suitable replacement:
<http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=20989&Row=41105&Site=US>

Ryan

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