USB Multilink

Started by marc...@yahoo.it July 28, 2006
Hi.
I have worked for about one year with the same USB Multilink.
Yesterday I broke 2 USB Multilink suddenly:
the cable became hot and after the blue light turn off.

I\'d like to understand what happened...

Can you help me?

Thanks....
Hello Marco,

this might be a ground loop between the PC and your target. If the
target GND is not at the same potential as the PC's ground then a
current flows through the USB cable which will destroy something --
usually the USB Multilink ...

--- In 6..., marcogalli80@... wrote:
>
> Hi.
> I have worked for about one year with the same USB Multilink.
> Yesterday I broke 2 USB Multilink suddenly:
> the cable became hot and after the blue light turn off.
>
> I\'d like to understand what happened...
>
> Can you help me?
>
> Thanks....
>
Thank you...
I thought so...

Hello Marco,
>
>this might be a ground loop between the PC and your target. If the
>target GND is not at the same potential as the PC's ground then a
>current flows through the USB cable which will destroy something --
>usually the USB Multilink ...
>
>--- In 6..., marcogalli80@... wrote:
>>
>> Hi.
>> I have worked for about one year with the same USB Multilink.
>> Yesterday I broke 2 USB Multilink suddenly:
>> the cable became hot and after the blue light turn off.
>>
>> I\'d like to understand what happened...
>>
>> Can you help me?
>>
>> Thanks....
>>
It's happened again. This time I'm sure that the gnd of the target is well connected to the interface. What can I do if the gnd of the PC is different from the gnd of the target? And how can I be sure that it is the problem?

Hi.
>I have worked for about one year with the same USB Multilink.
>Yesterday I broke 2 USB Multilink suddenly:
>the cable became hot and after the blue light turn off.
>I have changed PC 1 mounth ago..
>
>I\'d like to understand what happened...
>
>Can you help me?
>
>Thanks....
It's happened again. This time I'm sure that the gnd of the target is well connected to
the interface. What can I do if the gnd of the PC is different from the gnd of the
target? And how can I be sure that it is the problem?
Hi.
>I have worked for about one year with the same USB Multilink.
>Yesterday I broke 2 USB Multilink suddenly:
>the cable became hot and after the blue light turn off.
>I have changed PC 1 mounth ago..
>
>I\'d like to understand what happened...
>
>Can you help me?
>
>Thanks....
--- In 6..., marcogalli80@... wrote:
>
> It's happened again. This time I'm sure that the gnd of the target
> is well connected to the interface. What can I do if the gnd of the
> PC is different from the gnd of the target? And how can I be sure
> that it is the problem?

You should check for all supply voltages for correct pins (and not
also shorted to wrong pins).

Think about what changed when this started... new target board layout?
Jefferson Smith wrote:

> --- In 6...
































I have discovered that the neuter of my socket is 90 volt! and the case of my PC is 90V too.
The voltage supply of the target is isolated.
So it should't be a problem... or not?
Even if I started to use this PC 3 weeks ago, before I used a laptop that doesn't use the earth of the socket...

>Jefferson Smith wrote:
>
>> --- In 6... ,
>> marcogalli80@... wrote:
>> >
>> > It's happened again. This time I'm sure that the gnd of the target
>> > is well connected to the interface. What can I do if the gnd of the
>> > PC is different from the gnd of the target? And how can I be sure
>> > that it is the problem?
>>
>> You should check for all supply voltages for correct pins (and not
>> also shorted to wrong pins).
>>
>> Think about what changed when this started... new target board layout?
>>Run your target of an isolated supply (not grounded)
>
>Andrew Lohmann AMIIE
>Design Engineer
>
>PLEASE NOTE NEW EMAIL ADDRESS IS:
>a...@bellinghamandstanley.co.uk
>
>Bellingham + Stanley Ltd.
>Longfield Road, Tunbridge Wells, Kent, TN2 3EY, England.
>Tel: +44 (0) 1892 500400
>Fax: +44 (0) 1892 543115
>Website: www.bs-ltd.com
>>
>>
>-----------------------------Disclaimer-----------------------------
>
>This communication contains information which is confidential and may also be privileged. It is for the exclusive use of the addressee. If you are not the addressee please note that any distribution, reproduction, copying, publication or use of this communication or the information is prohibited. If you have received this communication in error, please contact us immediately and also delete the communication from your computer. We accept no liability for any loss or damage suffered by any person arising from use of this e-mail.
>
>-----------------------------Disclaimer-----------------------------
--- In 6..., marcogalli80@... wrote:
>
> I have discovered that the neuter of my socket is 90 volt! and
> the case of my PC is 90V too.
> The voltage supply of the target is isolated.
> So it should't be a problem... or not?

90V DC or AC? The AC phase matters. It's hard for me to see details of
your setup.
Usually there is only a few volts difference between Neutral and Earth.
There should be very little voltage difference between earth and water
taps say. When no current is drawn from the ground connection and the
target is not grounded depending on the mains input filtering you could
measure half the mains input voltage, or the voltage of neutral. Once
the ground is earthed no more than 1mA should flow, so your BDM cable
should not get hot with such a small, safe current. If more current
flows then it sounds like there is something very wrong with your
earthing or isolation.
Andrew Lohmann AMIIE
Design Engineer

PLEASE NOTE NEW EMAIL ADDRESS IS:
a...@bellinghamandstanley.co.uk

Bellingham + Stanley Ltd.
Longfield Road, Tunbridge Wells, Kent, TN2 3EY, England.
Tel: +44 (0) 1892 500400
Fax: +44 (0) 1892 543115
Website: www.bs-ltd.com

Jefferson Smith wrote:

> --- In 6...