Hi,

I have a problem with my Scart cable whereby I keep getting a shock from it!!

First I might need to explain my situation. I live in a block of flats where there is a communal dish providing both digital TV & Sky. This led to my 112x humming due to a ground loop (found this out by posting a discussion thread). To solve this I leave the Scart disconnected when not watching DVDs. When I want to watch a DVD, I disconnect the digital TV and Sky aerials from the wall socket and then reconnect the Scart to the back of my DVD player. This is when I'm getting an electric shock (not a strong one but very noticeable tingly feeling). This seems to happen when I am touching the DVD player and the Scart cable at the same time.

My equipment consists of Naim 202, 150X, CD5x, Flatcap 2x, NAPSC. DVD player is Pioneer DV-575A which is connected to my Sony TV via a QED 4130 Sqart RGB only Scart cable.

Is the cable at fault here? Someone said to me that because it is only RGB it doesn't have any earth pins and the cable is not earthing itself. I cannot test this theory at the moment because my Scart cable is 3m long and I don't have a replacement.

I'm trying to get an idea of what is at fault here before investing in a new Scart cable (if that is where the fault lies).

Any ideas or suggestions very welcome!!

You got hum because of an earth loop - caused by two paths to earth which are not equal. This causes a current flow through the SCART lead and you need to fit a ground loop isolator somewhere in the AV part of the system to block DC - probably in the aerial leads.

If you are getting a shock off the lead - imagine how your DVD player feels and take measures to stop risking damage as soon as possible.

Thank-you for your reply but why should this still happen with both the digital and Sky TV aerial disconnected from the wall socket?

On the ground loop isolator I haven't been able to find one which connects to my Sky Aerial (ie an F type aerial connection). I have searched since posting a topic on the HiFi thread about my ground loop problem a couple of months ago.

Does Naim recommend any particular solution to this problem?

Many thanks for your help

No - we don't really do such general problem solving.
Often it will require local investigation and your dealer or Sky installer is the first place to seek a solution.

Shocks are common with DVD->TV scart connection. TV chassis sit at half mains voltage.

SCART must have RGB and corresponding ground pins (R gnd, G gnd and B gnd) connected to work with RGB mode.

Whoever told you that is not telling the truth....

The SCART outer sheild (pin 21) is usually connected to the TV chassis (which is 1/2 mains..)

Thank-you for the TV explanation.

Do you happen to know of a solution to avoid this?

Thanks again for your help!!

The TV is effectivly isolated. The TV does not have a "ground" as such, so the chassis floats. The shock you get is minimal current, but still enough to wake you up.

When your SCART it connected, it is grounded by the unit it is plugged in to. If you sort your hum problem, you can then leave the scart plugged in...thus getting no shock

As Adam has already suggested, it is very likely you need to isolate your digi/sky-boxes from the "communal" signal/aerial feed, which is probably connected to other earths around the building.

Again, as Adam suggests, get your dealer/sky installer to look in to this

quote:

Originally posted by AV@naim:

Again, as Adam suggests, get your dealer/sky installer to look in to this

Why des this statement ggerally fill me with dread?!

quote:

Originally posted by PatG:
Why des this statement ggerally fill me with dread?!

I goudn'l nkow.

http://www.tinlee.com/ these guys are in Toronto but I'm sure if you call them they can sell you a 400 volt ground loop isolator they are broadcast quality and sell for about 20.00 buck Canadian
I'm not sure they show them on there web site but they do sell them, simple coax hook up female at both end.

steve

Sorry to drag this thread up but....

I have just become victim of my own advice.

Always remember to turn your TV off before plugging scart leads in.

TV scart input now dead.

Drat & Double Drat!

This message has been edited. Last edited by: Adam Meredith,