Quote:
Originally Posted by STurtle
No, not anymore nowadays:
The Scientific Atlanta Explorer4200DVB set-top box bears the "nested squares"-symbol of IEC Protection Class II Device and as such it does not require a connection to electrical earth. Therefore it features an unpolarised two-wire IEC-60320 C8 socket only. I also somehow recall an old rule-of-thumb that devices with metal cases always required grounding and hence could not achieve a Class II rating; but I know that this is not true any more since at least a decade.
Cutting it short: No, the STB is not grounded
- apart from the ground provided by the "cable" coming from VirginMedia, which is actually connected to the case (the plug is screwed onto a part of the case which deliberately lacks paint for that reason).
Before adding an extra ground wire, I measured about 1.6V DC and 0V AC between the STB-case and the earth-pin in my electrical socket. I also measured a DC current of a few Milliampere. I forgot the actual number, but it was small. It must be, since it does not trigger the RCD that I bought and plugged in between the socket and the STB now.
I wonder whether I should just continue to enjoy hum-free bliss or whether I should talk to VirginMedia about it. However, I doubt any replacement STB would do better anyway, so I guess I ignore it for now.
However, my limited electrical knowledge is restricted to "White Goods" only, so I would highly appreciate any input on the issue from anyone with actual expertise in "Brown Goods" or electronics. Thanks! |
Well there you go ! Something is obviously not right I have an optical connection to my AV Amp and a composite out using a SCART Splitter on the STB. I have no noise or pickup at all. As an observation my Yamaha AV Amp has a specific earth point on the case.
I must do a bit more research on this, apologies if I gave a bum steer. For anyone else reading this be VERY CAREFULL when measuring voltages around equipment, mains voltages can, and will kill.
I am intrigued by this, certainly every device I have opened up in recent years with a metal case has had an earth lead to the case. It may not require it, but what's the harm ? It may even help with EMC Shielding. Even my PC case has an earth point on the chassis, then again that has three pin IEC "Kettle Lead" so no surprise really !! D'oH.
Good luck, hope you get it sorted,