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Date:      Mon, 12 May 2003 01:53:24 +0200
From:      Marcin Dalecki <mdcki@gmx.net>
To:        ticso@cicely.de
Cc:        "Yevmenkin, Maksim" <Maksim.Yevmenkin@cw.com>
Subject:   Re: USB link cable?
Message-ID:  <3EBEE274.20105@gmx.net>
In-Reply-To: <20030511123016.GG1922@cicely9.cicely.de>
References:  <2E7E8A35375D1449A6F28D5E022E67310AC4D2@USSC8MS04.Global.Cwintra.Com> <3EBD2F95.9090807@gmx.net> <20030511005127.GD1922@cicely9.cicely.de> <3EBE3CB4.1000401@gmx.net> <20030511123016.GG1922@cicely9.cicely.de>

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Bernd Walter wrote:

> 
> Basicly the device is powered from the USB bus - of which there are
> two.
> It's quite possible that the vendor of your device failed to handle
> that situation correctly.
> Basicly it's possible to get an enourmous overvoltage if the +5V line
> gets connected before GND and your devices have different GND bases.
> Unless the vendor put the required overvoltage protection circuits into
> that device and they tried to take power from both sides it's strictly
> not hot-plug-able.
> 
OK. After a good half our of cutting through plastic I was able to
get a view of the pannel. There are just the 12MHz osc. the main
chip and two huge diodes there. And a bunch of passvie elements as usual...
There are two spare soldering places for transistors or maybe voltage
stabilizators... As much or better as few as I understand
from electronics two diodes are of course not enough to provide the
necessary electrical overload protection.
So I will assume thet your guess is very likely to be right.
Thanks for the educated explanation.

It was just my experimenting which simply made the accident waiting to
happen actually occur. Now my curiousity is satisfyed and I will just have
to by a new device...




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