Zapping firewire ports

Unfortunately, I have "zapped" the firewire ports on several camcorders.
(+ one firewire disk)
One (TRV900) was repaired, the others are just written off (still
working for recording though)

I *think* I understand why this happened.
It was because the PC was connected to an ungrounded 220v outlet.
See http://www.epanorama.net/documents/pc/ungrounded_pc.html

Since the PC ground can be floating at 110v it is easy to understand
that this could damage a firewire peripheral.

After I had a grounded outlet installed, I have not had another
incident, but I am still worried.

Anyone with experiences and/or ideas on the subject of zapped firewire
ports on camcorders?
Is this a common problem?

/Johan Stäck
Skellefteå
Sweden

 

If you think that you may have a grounding problem, and want
to go to the effort - there is one way that is probably better than
all others. Back in the 1960's we always installed what we called
a "true" ground to all mainframe computers. In the case of PCs, it
would be a copper wire attached to the case, then run to an 8 foot
long grounding rod. If you have noise, etc. - this can be a BIG help.
It is critical that the rod be in damp soil to make a good contact
with the earth, very dry soil will not work. You are grounding your
PC case directly to the earth, for a perfect ground. The thing that
I never could understand was "what is the earth grounded to"?

Gene

 

Some vendors (Sony, Apple, etc.) now caution against
"hot-plugging" Firewire cables because there have been
so many complaints about fried ports.

 

yes. I believe it is caused by a differential between the two devices'
grounds. However, some firewire ports have better protection at the inputs
than others. That said, we had a mac years ago that fried three times. In
different installations. with well grounded setups.

Have not yet fried a camera port.

 

I've been lurking in various video groups for a while, & this seems to
be a common problem when powering both the camera & computer off the
mains. Reports have been made of both ends being fried, especially in
situations where maintenance or care of cables may be suspect.

The recommended connection sequence is to disconnect the camera from the
mains, connect the firewire cable, then reconnect the camera mains power.

As I understand it the problem is caused by the protective earth on the
firewire connector not always connecting before the signal cables,
either due to a bad wire, or a bad connection inside the plug/ socket
assembly, giving a short pulse of up to 200 volts at the input & output
pins on the firewire connection, if either or both pieces of equipment
aren't grounded properly. Interestingly. I've never heard of a similar
problem on USB....

Tciao for Now!

John.

 

That makes a lot of sense.

I have found the tiny "4 pin" connectors to be iffy at
best. On at least two of my Sony camcorders
it takes a LOT of force to cause the 4 pin firewire
cable connector to make a good connection. A sloppy
built 4 pin firewire plug could easily short out if not
FIRMLY seated. They are a crimped plug, and the seam
is too close to the pins - bad design. As a general rule, I
NEVER power up , or power down the PC when a camcorder
it attached via firewire - whether the camcorder
has power or not. I have never fried a camcorder firewire
port, but can see where it could be very easy to do...

Gene

 

On 2/28/2007, Gene posted this:
[...]

I hope you're kidding with that question, but in case you're not, the
earth *is* ground.

That's precisely why the British call it "earth" - and why on this side
of the Atlantic we call it "ground".

In the old days, telegraphs used one wire for one side of the circuit
and the earth for the other.

Now we use it as a reference to prevent - and sometimes cause - shock
and other problems.

[...]

 

Yeah, just funnin'

Deep thought though

Gene

 

OK, looks like your humor is grounded in reality

 

nappy skrev:
am still worried.

Problem as I see it is that the camcorder is not grounded at all
(through the power supply that is).
The power supply uses un ungrounded connector, and the camcorder is fed
with low-voltage DC.

Someone in a swedish group commented that the camcorder is just like a
bird sitting on a high-voltage power line.
Since the bird is ungrounded it can be hurt.
The same would go for a camcorder connected to an ungrounded PC.

However, I have fried a number of firewire ports in camcorders, and I
need to understand how to prevent it happening again.

True as someone said, that this problem seems not to happen with USB!


But evidently one should
-keep everything grounded (as far as it can be done)
-avoid hot-swapping

/Johan

 

NEVER power ON or OFF the PC if the camcorder is connected
via firewire - even if the camcorder is turned OFF.

Gene

 

Wait a minute! I can't hot swap, AND I can't turn on the PC if a firewire
connection is plugged it? I think that leaves no choices? What's up?

Steve King

 

hmm.. overkill. While I did have firewire ports die on a MAc. I have
numerous FW cameras, decks,DVD recorders and audio interfaces and I have
never had a problem hot plugging any of those with a number of PCs for about
ten years now.

 

"Gene" wrote ...

Sony and Apple recommend the opposite.
That you ONLY connect a Firewire/iLink cable
when powered down.

 

I have seen that too, but I'm only suggesting what
has worked for me for a LOT of cycles and with five
or so different Sony and Cannon camcorders.

Here is what I do, and have never had a problem:

1. Power up the PC with the firewire cable plugged into the
PCI card, and the other end NOT plugged into anything.
2. With the camcorder powered down, plug the firewire cable
FIRMLY into the camcorder.
3. Power on the camcorder, the PC should see it.
4. BEFORE powering down the PC, power off the camcorder &
remove the firewire cable from the camcorder.

The above procedure may not work for every PC and camcorder
combination - so I would go with the advice of the camcorder
manufacturer if you are concerned. My reasoning for the above
procedure is that I feel the surge of powering up & down the
PC is more likely to zap my camcorder than attempting a hot plug
into a camcorder that is turned off. (NEVER do this if the camcorder
is powered-up in any way.)

The above has always worked for me. It may, or may not, work
for everyone - YMMV.

Gene