Author Topic: Eliminating electric shocks from your receiver  (Read 818 times)

Offline tsammyc

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Eliminating electric shocks from your receiver
« on: September 05, 2019, 12:52 »
For years, I have had a mild electric shock from my Yamaha receiver when I touch it lightly from the side. There is no shock when no equipment is connected to it, but when you connect Blu-Ray players, TVs, Apple TVs etc, the shock gets worse. I am able to measure the shock voltage using a voltmeter putting the + on the receiver and holding the - to ground it. With a single device connected, I get about 10v flowing through me. With the dozen or so things I have connected to it, the voltage rises to around 100v!! The current is very low, so I'm still alive, but its quite annoying to get a tingle when pulling out that HDMI cable.

Turns out, its simply because the receiver has a 2 pin plug and isn't grounded and my wiring system has a ground loop that gets worse as I add equipment. I could rewire the whole house...., but more sanely, I added a ground wire to the receiver, by simply connecting a wire to a screw in the chassis of the receiver and running it to the unconnected ground of the plug. No more shocks & QED.

Interestingly, the receiver sounds better. Perhaps there was an infrasonic hum from the ground loop, but I'm quite happy with this 5c cure.

Online rayleh

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Re: Eliminating electric shocks from your receiver
« Reply #1 on: September 05, 2019, 17:21 »
Any illustration especially unconnected ground of the plug?

Offline tsammyc

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Re: Eliminating electric shocks from your receiver
« Reply #2 on: September 05, 2019, 18:15 »
I just stripped the wire quite long and wrapped one side around the big ground pin on a 3pin plug several times, then strip and connect the other end to one of the screws on the receiver. That's it. To be clear, I didn't modify the 2 pin plug of the receiver. I just connect the chassis to the ground pin of another plug that is plugged next to the 2 pin plug. If you want to change the receiver's 2 pin plug to a 3 pin plug, then that would be even neater. Just connect the ground wire internally in the new 3 pin plug and run it alongside the power wire to the receiver, then ground it on any screw at the back of the receiver.

Offline Boxerfan88

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Re: Eliminating electric shocks from your receiver
« Reply #3 on: September 05, 2019, 21:13 »
My experience was a little different, no mild electric shocks but kena mild hum.

It was traced to a grounding issue, coming from the Starhub wall socket - to the TV antenna port - through HDMI - to the Yammy AVR (soft hum). Once I got rid of the Starhub coax antenna cable, all good. Maybe you wanna check this path.

For your case, I wonder if the phono input ground screw is a good place to ground the unit.
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Offline dbchoong

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Re: Eliminating electric shocks from your receiver
« Reply #4 on: September 05, 2019, 23:28 »
If the receiver is not plugged to any other electrical devices (media players, subs), still have that shock?

Offline Boxerfan88

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Re: Eliminating electric shocks from your receiver
« Reply #5 on: September 06, 2019, 07:00 »
If the receiver is not plugged to any other electrical devices (media players, subs), still have that shock?

disconnect TV as well...
best way to test is AVR & speakers only...


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Offline tsammyc

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Re: Eliminating electric shocks from your receiver
« Reply #6 on: September 06, 2019, 07:55 »
If the receiver is not plugged to any other electrical devices (media players, subs), still have that shock?

For me no shock, when receiver alone. Quite easy to test using a multimeter. I set at 0-200V, then +ve lead to the AVR chassis, -ve lead to my hand to allow current to flow through me to ground. Receiver alone 0V. Just Blu-Ray player 10V. Apple TV, Starhub Box, FireStick, TV etc connected, 100V

Unlike Boxerfan, I'm not connected to Starhub coax since I'm on FibreTV.

Offline Esquire

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Re: Eliminating electric shocks from your receiver
« Reply #7 on: September 06, 2019, 10:12 »
My system has current leakage especially when my feet is wet.
Can I ground it as in the picture below?




Offline pcking

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Re: Eliminating electric shocks from your receiver
« Reply #8 on: September 06, 2019, 11:53 »
Better not to ground it to phono.
Just choose a screw on the chassis and ground to AC earth of the same power point that this device is connected to.
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Offline watchdog

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Re: Eliminating electric shocks from your receiver
« Reply #9 on: September 06, 2019, 12:33 »
This is quite a common problem, especially when everything connected is two pin type. My Mac Mini used to zap the hell out of me when I touched it. Problem was traced back to the LCD monitor. 90V ! My friend passed me one of those grounding USB cables that connects to the earth prong of an AC outlet - problem solved.
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Online jerome_the_lang

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Re: Eliminating electric shocks from your receiver
« Reply #10 on: September 25, 2019, 22:24 »
I try to ground all my audio components wherever possible, either with a short wire inside the component, or externally, from the components' back panel into an adjacent ground receptacle.

For those hesitant about performing invasive soldering to do grounding inside your components, let me share with you some recent experiences doing external grounding.

A while ago, I was able to play around with a dealer's setup. Tried grounding their integrated amplifier first, and then the cd player. Both times we noticed audible differences. With just the amp grounded, soundstaging height increased by nearly a metre, the spaces between sound images cleared up and became less hazy, and consequently, imaging became better delineated, more pin point and more focussed. The soundstage became slightly more recessed further back behind the speaker baffles (if the speakers had been positioned further out from the wall, we are pretty sure the soundstage might recessed in towards the back further more). Overall, there is a weightier foundation to the music and we could listen at much louder volumes than before without getting fatigued.

When we tried grounding the cd player, the effects were the same, but not as pronounced as when the amp was grounded. However, when we lifted the grounding cable on the cd player off the carpeted floor, we then heard the same degree of improvements. It seems that the grounding cable we used can be very reactive with the materials that it came into contact with!

The grounding cable we used is a thinny video rca cable  (typically came supplied with cheap dvd players) that had been checked for signal flow directionality.

The source end was plugged into one of the unused rca input terminals of the amp and the other end was stripped and it's shield was connected to the ground pin of an uk ac plug (with both live and neutral pins removed) and plugged into the wall.

When this was done, straight away we noticed that the feeling of that perennial "buzz" on the front metallic faceplate of the amp was gone. (To feel the buzz, use the back of your finger.)

When the ground cable was unplugged, the buzz feeling (which is parasitic electric leakage current) came back.

Unplugging the ground, we noticed that the soundstage collasped immediately.

I briefly compared the ground cable plugged into Line1 input terminal vs Rec Out terminal, and i thought i can hear some differences, but I'm not 100% sure. It was very subtle.

The ground cable to the cd player was connected to the coaxial output terminal.

Cheap tweak that yield very big sonic improvements!

 

« Last Edit: September 25, 2019, 22:30 by jerome_the_lang »
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Online jerome_the_lang

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Re: Eliminating electric shocks from your receiver
« Reply #11 on: September 25, 2019, 22:35 »
It's easy to do this external grounding. No soldering involved.

I suggest to use a cheap coaxial/video rca cable that has a thin insulator jacket.

I think the thinner the cable jacket (dielectric) the less capacitance it adds to the cable.

Check the correct signal flow direction of this video cable.

Once you have determined the source end, it will be required to be plugged from the audio component you wish to be grounded.

The cut off the rca plug at the destination end. Strip the cable jacket for about 1 - 2 cm. Gather all the strands of shielding cables and twist them. Cut off the positive conductor core.

Connect the shield cable to the ground pin of an ac plug.

Both the live and neutral pins must be discarded (important).

Connect this ac plug to an adjacent ac receptacle with only the ground pin.

Try to make sure this grounding ac receptacle is the nearest to the component that you wish to ground.
« Last Edit: September 25, 2019, 22:37 by jerome_the_lang »
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