Home Cinema Leads - Shock Therapy!

Tesla · 3 Jun 2006 at 20:46

This one is a little odd.

I have set up many many bits of AV kit with no problems at all.

My own kit is a bit confusing.

I keep getting shocks off of the kit.

Usually the leads if I am unplugging something or moving a unit or testing something.

My kit comprises of:

Panasonic TX28PS12C CRT
Toshiba SD330 DVD Player (MR)
Marantz SR4200 AV Receiver
Sky+ (v1)
My PC is also connected to the amp via my homemade SPDIF cable.

So far I have been shocked by the following:

* Scart leads connected to the TV.
* The SPDIF cable connected to the amp.
* Satellite cable connected to the LNB (only when the mains is connected to the Sky)
* Scart leads when connected to the various bits of kit (so I unplug them from the TV).

I have never encountered this problem any of my customers kit, also, this problem hasn't always been apparent. It's just developed.

Any ideas for things to try to resolve it, it's getting rather annoying, sometimes the shocks are large enough to jolt my arm.

Ben · 3 Jun 2006 at 21:04

Could it be an earthing problem with the Sky+ box? I get shocks off my parents (Amstrad V2) one when touching anything metal related to the aerial socket on it.
Must admit haven't had anything off of any of the other sockets though. although most of them don't require you to touch the metal parts to unplug them.

Tesla · 3 Jun 2006 at 21:23

I think I will disconnect everything tomorrow and trace it down one by one.

Will take a while but it's getting on my nerves now!

Oops Dead Again · 3 Jun 2006 at 21:35

Have you got a tv booster anywhere?, I eventually traced my shocks down to a antenna booster I had.

philhoole · 3 Jun 2006 at 23:09

The effect you are seeing is I believe related to the products you have that are double insulated. These will be the ones that a have a 2 pin power connector. Your Sky box and DVD player would I guess be like this. Maybe the AV receiver too.

I'm not 100% sure on the details but it goes something like this. These products are double insulated and are designed in such a way that no hazardous volatge should reach the outer casing of the device. They don't need an earth due to the double insulated design. The "problem" comes when such a device connects to another and the connecting cable has an exposed shield such as a SCART or SPDIF. On an earthed device this shield will be at earth potential and you won't notice anything. On a double insulated device there is no ground/earth reference - so what volatge is on the shield of the cable? I believe it's typically at half mains volatge (115V ish).

Might sound terribly dangerous but I understand that there is very little current possible to flow (part of the design?) and you can't come to any real harm. Does make you jump though !