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Subject: Re: i knew better but......
From: brendan hack (bendy_at_bendys.com)
Date: 2004-04-06


Andreas Stemmer wrote:

>Brendan Hack wrote:
>
>
>>I just managed to blow the charging circuit on my original model recorder (20gig).
>>
>>From a previous email from Jörg I understand that I need an MC34063A to replace the existing chip on the back of the main board (which seems to be the one labelled 34063A in the bottom right of http://rockbox.haxx.se/internals/rec_iface_bottom.jpg, though I couldn't seem to find this chip on the schematic at http://rockbox.haxx.se/schematics/rec_main.pdf).
>>
>>
>
>Partially right. The "normal effect" of inserting a charger with wrong
>polarity is a blown MC34063A. You'll find it in the schematic of the
>_interface_ board.
>
>

Ahh, it helps if I look at the right page doesn't it. I thought since it
said rev2 on the main and rev2.1 on the interface that they were two
different version of the same circuit. I would have known better if I'd
actually followed the links.

>The picture on the rockbox website is a recorder with 6 or 10 GB and USB
>1.1! On my recorder 20 with USB 2.0, the layout is a little bit
>different, the MC34063A is on the top side of the interface board. You
>can easily find it by just removing the faceplate.
>
>

Yep, mine has the same layout now that I've opened it up and had a look.
The board says it a revision 1.3b interface board. Unfortunately the
soldering is definately beyond my abilities. Though I should be able to
find someone with the l33t skillz required.

>I recently repaired a jukebox with a blown charging circuit and the
>MC34063A was still intact. It was just a little smd ferrite bead which
>was blown. It was easy to find because it left a little crater on the
>pcb.
>
>

I couldn't see any craters so I assume my problem is with the MC34063A.
That is unless the bead you mention is on the underside of the board
though from what I can tell the +ve traces from the plug to the chip are
all on the top. The MC itself looks alright (doesn't look burnt or
anything, though the smell it still there), are there any test I can do
with my multimeter to check it? I actually have access to 2 recorders at
the moment with burnt out chargers, one looks fine and the other has
white scorch marks on the MC and black marks on the cover.

>
>
>>I'd just like to confirm that this is what I need and whether I need the 8-SOP or 8-DIP version. I think it's the 8-SOP going by the photo.
>>
>>
>
>Yes, 8-SOP
>
>

Thanks.

>
>
>>Also, does anyone know where I could pick one of these up in Australia?
>>
>>
>
>I don't know any distributor in Australia, but as a fallback solution,
>you could contact any manufacturer and ask for a free sample.
>
>

The Farnell web page seems to allow me to order these off the net though
I haven't been right through to the end of the process so I can't tell
if they only ship volume or not. They seem a bit pricey though at around
$7 each especially since the UK price is 61 pence. Maybe I'll have to
make some calls...

thanks for your help andreas

bendy

>Andreas
>
>_______________________________________________
>http://cool.haxx.se/mailman/listinfo/rockbox
>
>
>
_______________________________________________
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