My stereo line-in is at a slightly painful voltage. Should it be?
October 7, 2006 9:53 AM
The line in from my stereo seems to be live, as in it's marginally painful to touch. Should it be?
To clarify, this is the cable I normally plug in to my laptop to put sound through the stereo. So it's connected to the stereo, and connected to the bits that accept a signal rather than put one out.
Is it time to chuck the stereo and get a new one? I imagine if it's not supposed to be at a fair old voltage it's not something I want to be plugging into my Macbook.
To clarify, this is the cable I normally plug in to my laptop to put sound through the stereo. So it's connected to the stereo, and connected to the bits that accept a signal rather than put one out.
Is it time to chuck the stereo and get a new one? I imagine if it's not supposed to be at a fair old voltage it's not something I want to be plugging into my Macbook.
I'm in the UK, so it's not going to be 110 volts. If it were 240 I'd imagine it'd induce more than an uncomfortable tingle.
The cable's also the original and I don't think there's any plausible way it could be miswired without me having noticed before, and it's physically impossible to plug it in the wrong way round.
posted by edd at 10:14 AM on October 7, 2006
The cable's also the original and I don't think there's any plausible way it could be miswired without me having noticed before, and it's physically impossible to plug it in the wrong way round.
posted by edd at 10:14 AM on October 7, 2006
Got a voltmeter? Maybe the outlet is miswired. Try it somewhere else in the house.
posted by weapons-grade pandemonium at 10:27 AM on October 7, 2006
posted by weapons-grade pandemonium at 10:27 AM on October 7, 2006
Unfortunately I've not got a voltmeter handy, no.
I'd be surprised if this were an issue at the mains end. It's plugged into an adapter along with a few other things, none of which are acting at all oddly. The stereo (a mini thing with cd, radio and associated electronics) acts in all other ways fine, and it amplifies sound from the linein just fine. I can't imagine it being something wrong on that side of the stereo's power supply.
posted by edd at 10:58 AM on October 7, 2006
I'd be surprised if this were an issue at the mains end. It's plugged into an adapter along with a few other things, none of which are acting at all oddly. The stereo (a mini thing with cd, radio and associated electronics) acts in all other ways fine, and it amplifies sound from the linein just fine. I can't imagine it being something wrong on that side of the stereo's power supply.
posted by edd at 10:58 AM on October 7, 2006
If it were 240 I'd imagine it'd induce more than an uncomfortable tingle.
Not necessarily. It's the amps that kill you, not the volts.
posted by The Michael The at 11:28 AM on October 7, 2006
Not necessarily. It's the amps that kill you, not the volts.
posted by The Michael The at 11:28 AM on October 7, 2006
Is any part of the system hooked up to a cable TV outlet? At least one or two times I've had hot current coming out of a cable TV outlet. I'm astonished it didn't fry anything, but fortunately calling the cable company fixed it.
posted by rolypolyman at 11:31 AM on October 7, 2006
posted by rolypolyman at 11:31 AM on October 7, 2006
No, nothing else plugged in to it.
It's one of these so people know what we're talking about.
posted by edd at 11:36 AM on October 7, 2006
It's one of these so people know what we're talking about.
posted by edd at 11:36 AM on October 7, 2006
It sounds like there's a grounding issue, either at the outlet or the stereo itself.
If the stereo's plug is 2-pronged, I'd guess it's the stereo itself. If it's 3-pronged, it could be the outlet and you should call an electrician.
A 3-pronged outlet is one which contains a ground wire that is connected to the chassis. This means that if there's *any* situation in which the chassis becomes accidentally connected to a "hot wire", it immediately blows a fuse or breaker to prevent you from getting shocked.
If the stereo is 2-pronged, it probably *doesn't* have this protection, and therefore if the chassis becomes "hot" then it becomes dangerous.
I'm in the UK, so it's not going to be 110 volts. If it were 240 I'd imagine it'd induce more than an uncomfortable tingle.
That's not necessarily true. The "circuit" in this case is from the chassis of the stereo to the "input" wire, to your hand, to the ground. Therefore, there are all sorts of things that can get in the way of this loop and cause resistance. Wearing shoes, for example, could reduce the voltage significantly and make the difference between life-threatening and annoying.
I'd be surprised if this were an issue at the mains end. It's plugged into an adapter along with a few other things, none of which are acting at all oddly.
That doesn't guarantee that it's not the mains. Some things (like AC adapters) simply don't have a chassis on which to expose itself to grounding issues. In fact, 2-pronged electronics are generally ones in which it's not expected that a hot wire could be easily exposed, although it does happen sometimes.
In any case, you really should not touch the thing to "test" it anymore, as you might have been lucky so far to not have been seriously shocked. Buy a voltmeter, connect one end to a proper ground wire, and the other end to whatever you want to test.
posted by helios at 12:12 PM on October 7, 2006
If the stereo's plug is 2-pronged, I'd guess it's the stereo itself. If it's 3-pronged, it could be the outlet and you should call an electrician.
A 3-pronged outlet is one which contains a ground wire that is connected to the chassis. This means that if there's *any* situation in which the chassis becomes accidentally connected to a "hot wire", it immediately blows a fuse or breaker to prevent you from getting shocked.
If the stereo is 2-pronged, it probably *doesn't* have this protection, and therefore if the chassis becomes "hot" then it becomes dangerous.
I'm in the UK, so it's not going to be 110 volts. If it were 240 I'd imagine it'd induce more than an uncomfortable tingle.
That's not necessarily true. The "circuit" in this case is from the chassis of the stereo to the "input" wire, to your hand, to the ground. Therefore, there are all sorts of things that can get in the way of this loop and cause resistance. Wearing shoes, for example, could reduce the voltage significantly and make the difference between life-threatening and annoying.
I'd be surprised if this were an issue at the mains end. It's plugged into an adapter along with a few other things, none of which are acting at all oddly.
That doesn't guarantee that it's not the mains. Some things (like AC adapters) simply don't have a chassis on which to expose itself to grounding issues. In fact, 2-pronged electronics are generally ones in which it's not expected that a hot wire could be easily exposed, although it does happen sometimes.
In any case, you really should not touch the thing to "test" it anymore, as you might have been lucky so far to not have been seriously shocked. Buy a voltmeter, connect one end to a proper ground wire, and the other end to whatever you want to test.
posted by helios at 12:12 PM on October 7, 2006
Go here and tell them all about it. Hopefully you'll get a timely response. In the meantime quit touching that in line.
posted by sgobbare at 12:16 PM on October 7, 2006
posted by sgobbare at 12:16 PM on October 7, 2006
Oh I don't touch it deliberately - I'm not one for subjecting myself to unnecessary discomfort, and I'm certainly not in the business of conducting experiments using myself and obviously high voltages. sgobbare: Thanks for the link - it's US only but it does lead on to useful places.
Anyway, the gist of it seems to be that line-ins shouldn't do this. I suspect the best use of my time and money is to trash it and replace it with a new unit. It won't be worth me getting an electrician to dig around and fix it I wouldn't have thought.
posted by edd at 12:34 PM on October 7, 2006
Anyway, the gist of it seems to be that line-ins shouldn't do this. I suspect the best use of my time and money is to trash it and replace it with a new unit. It won't be worth me getting an electrician to dig around and fix it I wouldn't have thought.
posted by edd at 12:34 PM on October 7, 2006
I should add just to answer helios's question - it's 2-pronged (the earth pin is plastic).
posted by edd at 12:36 PM on October 7, 2006
posted by edd at 12:36 PM on October 7, 2006
I suspect the best use of my time and money is to trash it and replace it with a new unit.
Not necessarily. I had a similar problem and got some good answers. It turned out that all my equipment was fine, but the outlets in my apartment weren't grounded properly. I got an electrician in and he diagnosed and fixed the problem in less than an hour.
posted by fuzz at 3:09 PM on October 7, 2006
Not necessarily. I had a similar problem and got some good answers. It turned out that all my equipment was fine, but the outlets in my apartment weren't grounded properly. I got an electrician in and he diagnosed and fixed the problem in less than an hour.
posted by fuzz at 3:09 PM on October 7, 2006
I had a similar problem - a 9V DC wall-wart transformer that correctly produced 9V difference between negative and positive, ie relative to each other, but relative to ground, but they were floating about 90V AC from ground (this was in a 240V country).
So if it's possible to replace the power supply (such as if it's a wall-wart adapter), that might be easier than chucking the whole thing, and is highly likely to fix it. Otherwise, don't plug it into expensive gear, like your laptop :)
Incidentally, if you want to check what the voltage is that you can feel, connect one prong of a multimeter to the line-in, and hold the other prong. Check the multimeter reading in both AC and DC.
posted by -harlequin- at 10:10 PM on October 7, 2006
So if it's possible to replace the power supply (such as if it's a wall-wart adapter), that might be easier than chucking the whole thing, and is highly likely to fix it. Otherwise, don't plug it into expensive gear, like your laptop :)
Incidentally, if you want to check what the voltage is that you can feel, connect one prong of a multimeter to the line-in, and hold the other prong. Check the multimeter reading in both AC and DC.
posted by -harlequin- at 10:10 PM on October 7, 2006
Also, in the 9V adaptor that floated at 90V AC, running a finger over the metal case of the music player produced a sensation that felt like it was vibrating slightly. Took me ages to figure out something was wrong :)
posted by -harlequin- at 10:13 PM on October 7, 2006
posted by -harlequin- at 10:13 PM on October 7, 2006
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posted by weapons-grade pandemonium at 10:04 AM on October 7, 2006