What would cause a mild shock in an amplifier?

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Autor
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particleman
Stammgast
#1 erstellt: 24. Sep 2009, 16:29
Hi,

I have had my amplifier (Arcam FMJ A28 integrated) and cd player (Arcam FMJ CD37) for several months now - 1 year and 6 months, respectively. I have noticed in the last few weeks that the front plate of the amplifier gives a bit of a buzz when touched. I am not sure how to describe it better, it is not a violent shock but a mild tingle. It does not go away on being touched once but remains as long as it is switched on.

Both devices are connected to a Belkin spike suppression strip and are the only two devices connected to it. They are connected by a generic pair of 3-pin cables.

Interestingly enough, when I bought the CD player I got this buzz on it too -- switching the stock 2-pin cable (ground pin missing) provided with the units, with these Indian cables solved that problem 6 months ago. All was fine until a fortnight ago. No changes were made in that time, nothing was moved (only the speakers but no connections were touched).

Had they been connected to the mains I would have guessed that the pins were to be inverted. But they are both connected to the same spike strip and only one unit, the amp, gives a shock. Given that this is a high quality product I am for the moment ruling out product fault. And I hope this is the case.

A big handicap is that I do not have access to a qualified electrician. The only one I know, I wouldn't allow within a hundred yards of this equipment - the last time he tried to "help", he yanked a speaker cable out of the binding post without pressing the release (not these speakers).

I would be most interested in your theories on what could be going wrong? Do you think investing in better power conditioning would solve this problem? Is this related to the monsoon?

Here's to a less shocking listening experience.
Amp_Nut
Inventar
#2 erstellt: 24. Sep 2009, 17:42
Temporarily put the 2 pin Mains cord back on the CD player, and try with the 2 Pin Plug Inverted and normal ( relative positions, of course )

I am betting that one way, there will be no 'tingle'


BTW... you dont have a DVD player or any other appliance connected to the Amplifier ?
msb1
Stammgast
#3 erstellt: 24. Sep 2009, 17:59
Could be a weak ground. Check your voltage between Hot and Ground and Neutral and Ground and post.
Also, have you tried inverting the 2 pin connectors on the Belkin strip? Your polarity may be wrong.
bombaywalla
Stammgast
#4 erstellt: 24. Sep 2009, 23:12

Interestingly enough, when I bought the CD player I got this buzz on it too


when you plugged in the Arcam CDP & got this "buzz", did you plug it into the Belkin power strip OR directly into the mains outlet?



All was fine until a fortnight ago. No changes were made in that time, nothing was moved (only the speakers but no connections were touched).


hmmmmmmm.....
A connection that was working just fine for the past 6 months suddenly started acting up.....
You are SURE that no connections were changed by you or any other household member???


I'm trending along the same lines as member MSB1 - a weak ground.
Pop open your Belkin power strip & check the ground connection in that unit.
Pop open the Arcam amp & check its gound connection at the IEC connector.
As msb1 already suggested, measure the voltages between plus-earth, neutral-earth, plus-minus. Ensure they measure what they should.
particleman
Stammgast
#5 erstellt: 01. Okt 2009, 11:38
Hello all and many thanks for your most helpful replies. My apologies for my last response as work has been extra hectic of late. Did not get a chance to test anything till last evening. I could not get an electrician due to the Dassera holidays so this is still my fiddling about and the results thereof.

[Also, I should probably mention that the sensation in question is not an outright shock. If you place a finger on the front face of the amp and leave it for a second there is a mild buzz. A screwdriver style "shock detector" does not pick up anything at all so that tells you how low it is.]

I plugged the amplifier into another point on the Belkin and made sure that all cords were well fitted. Then turned on the system.

As before there is no tingle or anything of the sort on the amp when switched or in the first few minutes. After playing for about 30 minutes, I noticed the same buzzing sensation when I placed my finger on the front of the amp. No shock on the buttons themselves. Even milder than last time, almost absent.

Curiously though, after I played for about 2 hours or so, I touched it again and this time it was simply warm as it should be but no more buzz. So I can't figure it out but I am a lot less worried now.

I will have the electrician test the points as you have all kindly explained in detail, as I don't have such testing equipment. I am also keen to ditch the Belkin and get better power protection at a reasonable price (i.e. < 20k). Maybe even have a dedicated power line put in.

[Disclaimer: I am an electricity illiterate so pardon the silly questions]

@AmpNut
I will try to swap with the 2-pin cord. One worry, if I am getting a mild buzz on a plug with third pin won't it be worse when there is no third pin? I will try it out tomorrow morning when I reach home and report back.

No other appliances connected at all except the Arcam SACD player and that too is connected only via interconnects to the amp. That is, the CD player draws its power independently from the Belkin strip and is not plugged into the amp (I guess some amps have this feature?).

@msb1
I will have the electrician do a thorough testing of all points. I will try with the 2-pin cable and see if inverting has any effect.

@bombaywalla
The problem with the Arcam SACD was noticed as soon as I plugged it in after purchase. At the time both amp and player were connected to a MX style cheapo spike strip. With the original 2 pin plug supplied by Arcam, it gave a very sharp buzz on all buttons and right away on powering up. It was impossible to touch the player's buttons without significant discomfort. It was a definite shock not a buzz or tingle. When I changed the power cords for some Indian made generic 3 pin power cords the problem went away and hasn't returned. I got the Belkin a few weeks after the CD player and there were no problems until very recently. Neither component was ever connected direct to the mains outlet as they are too far away.

Double and triple checked with the family that nothing was moved or touched. I will have the electrician conduct tests and see what the findings are.

--

Again, thanks all for your valuable guidance. I will be sure to update as things progress. I am feeling more relieved now that I know it is less likely to be an amp fault. Hope the electrician catches the culprit.
Amp_Nut
Inventar
#6 erstellt: 01. Okt 2009, 13:11
Hi Particleman,

Thanks for your feedbacl. I was looking forward to it.

1. Regarding the 'perplexing' matter of you feeling shock only intermitently, I speculate that you had changed your FOOTWARE ( ! ) in each instance ???

If you have Rubber based soles / chappals, you will probably not feel anything. Will feel something with leather soles and WILL Feel if you are bare footed/ only socks.

Would appreciate your feedback on my above speculation ( you can try it out again tonight ).


2.


@AmpNut
I will try to swap with the 2-pin cord. One worry, if I am getting a mild buzz on a plug with third pin won't it be worse when there is no third pin? I will try it out tomorrow morning when I reach home and report back.


No Sir, the 3 pin plug wont help. Yr CD player has an Isolated chasis, and thats why it originally came with a 2 Pin plug.

Do try my suggestion and revert.

( No electrician required for Either of my suggestions, & I believe point 2 will cure the problem... Presumptuous me )


[Beitrag von Amp_Nut am 01. Okt 2009, 13:13 bearbeitet]
msb1
Stammgast
#7 erstellt: 01. Okt 2009, 13:50
Amp_nut could be right.
But if you want to fix the problem connect a wire from any point of the chassis to the electrical ground - this is the centre hole (located above the other 2) in a 3 pin socket. Please be careful and not put the wire in any of the others. If you don't know what you are doing, ask someone who knows what the ground (earth) is.
particleman
Stammgast
#8 erstellt: 14. Dez 2009, 12:45
Just wanted to update everyone.

I had the electrician check the grounding on mains and spike strip, and it was okay.

I then switched back to the original power cord that I got with the amp. I don't know if that is what did it but now I am not getting the tingle any more. Amp_Nut, you were spot on!

This is a huge relief to me and I can now get back to enjoying my music. A very big thank you to ALL of you who took time out to help me with this:
Amp_Nut,
msb1,
bombaywalla.

Much appreciated.
Amp_Nut
Inventar
#9 erstellt: 14. Dez 2009, 13:36
GREAT !
Glad that music listening is no longer a 'shocking' experience

Jeeves
Stammgast
#10 erstellt: 18. Dez 2009, 12:48
I get a lot of "shocks" in winter and when its dry due to static. I must look funny to others ...I always quickly touch some metal before I switch on the system!
Krish
Stammgast
#11 erstellt: 24. Dez 2009, 09:48

Jeeves schrieb:
I get a lot of "shocks" in winter and when its dry due to static. I must look funny to others ...I always quickly touch some metal before I switch on the system!


hey that happens to me as well ...and even in Mumbai!
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