Does the circuit require a secondary CT? If so, you need to provide it. If not, you do not need to provide a CT and if one is present you should ignore it and certainly should not ground it. You seem to be fumbling in the dark here. Do you understand power supplies? Who built the one with the faults in it?donovas said:
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so this is the circuit im going by
http://www.diyaudio.com/forums/attachments/analog-line-level/487353d1433781712-tube-ss-preamp-apex-cunterpoint-schematics1.jpg
like i said, the whole machine turns on when i connect the signal ground to earth via back to back resistor.
but as you can see on the circuit, the output is shorted to ground when the relay is not active. could it be the shock im getting is from residual charge in the smoothing cap after the regulator? and the residual charge is unable to drain because i dont have the earth connected.
so this is the circuit im going by
http://www.diyaudio.com/forums/attachments/analog-line-level/487353d1433781712-tube-ss-preamp-apex-cunterpoint-schematics1.jpg
like i said, the whole machine turns on when i connect the signal ground to earth via back to back resistor.
but as you can see on the circuit, the output is shorted to ground when the relay is not active. could it be the shock im getting is from residual charge in the smoothing cap after the regulator? and the residual charge is unable to drain because i dont have the earth connected.
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Oh oh that is not wise ! This is a device that must have its case tied to PE. It has a metal chassis probably (I see you have a wooden case but still there will be metal parts) and lethal voltages anyway so all exposed metal parts must be connected to PE certainly when it is a DIY device. With tube gear it is wise to reference audio GND to PE. The back to back diode system works. It wonders me what there is different in your friends house. I think he has a problem with his electrical system. This way of working without PE is very dangerous. Even in normal state you get shocks, now suppose what happens if a real failure occurs.
This indicates a serious issue in the home of your friend. It seems that PE has a voltage on it in his home. It can be a combination of a failure in your DAC and a failure in the electrical system but in all cases you will have to have a certified electrician look into it. This can be a very dangerous situation for your friend and his family. First have his installation checked and don't use the DAC for now until you know what is wrong in the house of your friend. If that is solved pay then attention to making the DAC PE connected.
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My guess is that earth is floated in my friend's place, and creates an ac loop, effectively making it another ac polarity when i connect the ground wire to it. At my place there is no separate earth wiring (a lot of old places in korea are like that) and instead one ac polarity has more ground potential (i think) so the current is able to drain out into that.
What i plan on doing is
-get a new 110v transformer wound with earth tab (its an ei transformer)
-get a metal plate to mount all the transformers on and earth the plate
-maybe get the 110v transformer center tapped and earth it too?
Hopefully these will do the trick. What do you think?
What i plan on doing is
-get a new 110v transformer wound with earth tab (its an ei transformer)
-get a metal plate to mount all the transformers on and earth the plate
-maybe get the 110v transformer center tapped and earth it too?
Hopefully these will do the trick. What do you think?
At last.
You are finally stating that the the second rule applying to exposed conductive parts does apply!
Why in so many other posts do you insist that we should not be making this Safety connection?
Are you still in the UK?
Then buy a little mains Tester. CPC sell it for under £2.
Just plug it into your socket outlet and read off the lit/unlit lights.
Do this for ALL your socket outlets.
If any do not comply then call in an Electrician to sort out your house wiring.
Do you have a Multimeter?
Measure the voltage difference between the two pieces of audio equipment. clip onto one RCA of item A and clip onto one RCA of item B.
What does the Vac read?
A 5V 3VA DAC with molded mains transformer or a 250V DC tubed device with exposed parts already giving shocks makes some difference. Plus no PE in the home while having problematic high voltage stuff....
English is not my language but if you see how I build my stuff you would understand my point I think. besides that you quote me out of context. I don't say not to connect PE but I do say not to connect with 0 Ohm. There are solutions that still are safe but don't cause a ground loop. I deliberately try to avoid the words "ground lifting" as that might give the wrong impression. I have seen the switches in PE connections on old guitar amps, that is why. These were often called "ground lift" and are forbidden by law.
I always encourage to connect a metal chassis to PE and reference (so not a 0 Ohm) audio GND to PE in power amps and tube devices. In all other devices I don't connect audio GND to PE but I do connect the case to PE if applicable. I find it a challenge to build my own low power stuff without any PE connection and still make it safe but that is my challenge ( I use a medical isolation transformer). Local regulations tell me I don't need to connect GND to PE. We don't connect all low power devices (DACs, DAB+ tuners, preamps) with audio GND to PE as is done in UK made stuff. We don't and we won't. Thankfully the UK does not rule the world with regards to electrical safety.
Clear now ?
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No not clear now.
PE is different from your repeated diatribes to NOT connect the audio ground to the chassis.
Yet in that quoted post you said the opposite.
and in your latest rely you say the opposite yet again
Make up your mind.
Which is it that you recommend?
PE is different from your repeated diatribes to NOT connect the audio ground to the chassis.
Yet in that quoted post you said the opposite.
I don't see that as out of context. You wrote that.
and in your latest rely you say the opposite yet again
Make up your mind.
Which is it that you recommend?
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You are clearly provoking and taking sentences out of context. We don't follow silly UK regulations to connect every device its audio GND to PE and always have ground loops. Simple ! Our regulations differ from yours as we don't have to connect secondary side of a PSU GND with PE with low power devices. Exposed parts are here seen as external parts like knobs, switches etc. Audio GND in the form of a rail or something is NOT seen as an exposed part. Metal cases/chassis are connected to PE unless it is a Class II device then the metal case is not even connected to PE. It is fully legal to build Class II devices yourself here and the rules are not that hard but responsibility is for the builder. Counts for Germany and the Netherlands. Please tell me we are living dangerously and you guys know whats best. You always do.
However, on this international forum, when unexperienced or people with unknown abilities are DIYing tube gear with very high lethal DC voltages I best advise to definitely keep the case connected to PE and reference audio GND to PE for safety. The secondary side of the PSU has even higher voltages than the primary side. Not everyone is experienced enough to see potential dangerous situations or is able to wire up devices a safe way. Not everyone is aware of Class II nor how to do that.
I personally think it is a challenge to design my devices without PE at all with low power devices but I use a medical isolation transformer reducing risks and I know how to do stuff and i am the only one using my devices. IF I use PE at all it is only connected to cases in certain devices as i never connect audio GND to PE but I mostly build low power devices and not power amps etc. What I do with my own stuff is my business.
However, on this international forum, when unexperienced or people with unknown abilities are DIYing tube gear with very high lethal DC voltages I best advise to definitely keep the case connected to PE and reference audio GND to PE for safety. The secondary side of the PSU has even higher voltages than the primary side. Not everyone is experienced enough to see potential dangerous situations or is able to wire up devices a safe way. Not everyone is aware of Class II nor how to do that.
I personally think it is a challenge to design my devices without PE at all with low power devices but I use a medical isolation transformer reducing risks and I know how to do stuff and i am the only one using my devices. IF I use PE at all it is only connected to cases in certain devices as i never connect audio GND to PE but I mostly build low power devices and not power amps etc. What I do with my own stuff is my business.
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Normally there is a set of regulations and rules in a country for building safe electrical installations. Normal citizens have no clue about that, they just use the installations. In your case something is not OK. You are not educated in electricity nor do you know how to find the fault or understand what is wrong. There is nothing wrong with not knowing something that is not your expertise. It is then best to have someone experienced/certified look at what is wrong as it is your safety and that of those that live in the same house.
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