Electrical Shock from Casing

Guys,

When I touch the screw on the casing of my tube buffer, I got an electrical shock. It light up when I test with a test pen. Have you guys ever encountered this before ? Is it power leaking ? Would it harm the equipment that I connected to ?

How to solve this ?

There are two possibility, assume your tube buffer is normal. May be your system are not connect to earth or your electric power supply polarity is reverse( neutral & hot is reverse)

kkthen wrote:There are two possibility, assume your tube buffer is normal. May be your system are not connect to earth or your electric power supply polarity is reverse( neutral & hot is reverse)

kkthen,

I suspect no grounding to the earth. Any idea how to do that ?

hi sskong...astro decoder also sometime will cause the problem...

fizi wrote:hi sskong...astro decoder also sometime will cause the problem...

I'm not connected to astro.

Which tube buffer are you using?

clone MF x10-D

My friend's Yaqin tube buffer does only give humming sound after it has warm up, once you touch the casing, it will goes off.

kkthen wrote:There are two possibility, assume your tube buffer is normal. May be your system are not connect to earth or your electric power supply polarity is reverse( neutral & hot is reverse)

This is true. trust what is said here.

It is some form of current leakage, due to the device not being grounded. What you do is you look for a screw where you can tap a short piece of wire. Then you hook up the other side to the earth terminal of a plug. Just earth the device somehow and you should be OK.

kakibook wrote:

kkthen wrote:There are two possibility, assume your tube buffer is normal. May be your system are not connect to earth or your electric power supply polarity is reverse( neutral & hot is reverse)

This is true. trust what is said here.

that is SOOOO not true. a reversed neutral hot will neither fix nor contribute to the missing-earth problem.

mugenfoo wrote:

that is SOOOO not true. a reversed neutral hot will neither fix nor contribute to the missing-earth problem.

Yes you are right. reversed neutral hot will cause current leakage only for some two pin plug electric equipment only. example marantz cd63se, when connect it with reverse polarity but don't switch on the player, if you try to use test pen to touch the rca output, you will find out the test pen will light up. But with correct polarity, current leakage problem will be solved, that is why people say wrong polarity will cause system sound bad. Actually the current leakage spoil the sound quality. But some player like sony dvd player , current leakage problem will happen either the polarity is correct or wrong, only one way is being grounded.

this topic has been discussed before. again and again, old topics are discussed.

kakibook wrote:this topic has been discussed before. again and again, old topics are discussed.

Ever considered that maybe this is because in the spirit benefiting the newcomers, facts needed to be stressed over and over again. Just like a teacher in a classroom.

kkthen wrote:

mugenfoo wrote:

that is SOOOO not true. a reversed neutral hot will neither fix nor contribute to the missing-earth problem.

Yes you are right. reversed neutral hot will cause current leakage only for some two pin plug electric equipment only. example marantz cd63se, when connect it with reverse polarity but don't switch on the player, if you try to use test pen to touch the rca output, you will find out the test pen will light up. But with correct polarity, current leakage problem will be solved, that is why people say wrong polarity will cause system sound bad. Actually the current leakage spoil the sound quality. But some player like sony dvd player , current leakage problem will happen either the polarity is correct or wrong, only one way is being grounded.

Using a test pen is empirical at best. A better home-DIY way is to MEASURE the flux leakage with a simple voltmeter set to measure AC volts. The correct polarity would be such that the measured voltage from the RCA's negative output to the home wall socket EARTH pin gives the LOWEST READINGS.



(and I will explain this phenomenon in a totally scientific and simple way for everyone to understand the reason behind the results)

All transformers are not perfectly wound (winded). There would be an optimised way (or polarity) such that all the electromagnetic field (generated from the AC source) from the primary coil would be inducted into the secondary coil.

At the correct polarity, the transformer is deemed to be operating more efficiently as more electrical energy from the primary coils is transferred to the secondary coil. The remainder of whats not transferred would translate into heat, and electrical leakages to chassis ground.

So when the transformer is connected with the right polarity, there is less leakage into the chassis ground. The voltmeter would read a lower AC voltage between the chassis ground (or the RCA jack's negative point) and true earth (your home wall plug's earth connection). If wrong polarity (actually not exactly wrong, but less optimal) would mean that less juice from the primary coil gets sent to the secondary coil, and there are more losses to chassis ground and more heat build-up in the transformer metal cores (actually ferrite or laminated steel or iron cores; the lamination being to reduce "Eddy" currents which are bad).

So perhaps the Marantz has a more "fussy" transformer. Whereas the Sony transformer is more polarity agnostic. But even for the Sony transformer, there would be one polarity which would yield better performance (& eventually better sound quality) vs a flipped polarity.


obi-wan-kenobi: "Use the force (voltmeter) Luke, use the force (voltmeter)!"

It is some form of current leakage, due to the device not being grounded. What you do is you look for a screw where you can tap a short piece of wire. Then you hook up the other side to the earth terminal of a plug. Just earth the device somehow and you should be OK.

If using abovementioned method to a preamplifier, one must be aware that the power amplifier is grounded as well, else if the power amp has leakage, the current will flow thru the RCA to preamp and into ground, you will have badly oscillation and might cause damage to the power amp as well as the speaker itself..

wabun wrote:

It is some form of current leakage, due to the device not being grounded. What you do is you look for a screw where you can tap a short piece of wire. Then you hook up the other side to the earth terminal of a plug. Just earth the device somehow and you should be OK.

If using abovementioned method to a preamplifier, one must be aware that the power amplifier is grounded as well, else if the power amp has leakage, the current will flow thru the RCA to preamp and into ground, you will have badly oscillation and might cause damage to the power amp as well as the speaker itself..

But must be careful not to over-ground too much. otherwise it can create a ground-loop and this results in hum and the voltages differences can flow in nasty paths or even oscillate within the ground-loop. Ground-loops can also colour the sound because the loop would have a resonance at certain AC components. This would compromise the amp's linearity.

Best is to have a "Star-topology" ground. Especially if the pre-amp's outputs signal ground is floated. Then adding additional DIY grounds might cause hum. Again, its very equipment specific.

WongKN wrote:It is some form of current leakage, due to the device not being grounded. What you do is you look for a screw where you can tap a short piece of wire. Then you hook up the other side to the earth terminal of a plug. Just earth the device somehow and you should be OK.

Guys,

Problem solved as per WongKN advise. Thanks.

Since you got that added earth wire in place now, suggest for you to unhook it temporarily at the chassis end, and then use a voltmeter (set it to measure AC volts) to measure whats the voltage difference from the unhooked wire to the chassis. Do this again with the AC plug connection flipped.

Then choose the AC plug position where you would read the LOWEST voltage. You may then re-hook back the earth wire onto the chassis to remove the "electric shock" problem.