Elements between PCB-GND and Mains Earth in SolidState Power Amps - How to Calculate? - Page 3 - diyAudio
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Old 18th June 2012, 03:16 PM   #21
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Quote:
Originally Posted by AndrewT View Post
Post8
thank you. This slang term is probably not the most common in the english language and thus it was new for me.
Google provides except this thread this URL:
Understanding Star Grounding
Dynaco-Doctor Forum
by follow topic it was call "Ground loop Isolator":
Is Gainclone Direct Coupled? Appropriate Preamp?
Quote:
Originally Posted by AndrewT View Post
Post 1
The pic shows the Audio Ground connected to the Safety Earth via a Disconnecting Network of 100r//0u22F.

TEST that arrangement.

I bet
1.) the Disconnecting Network blows up.
2.) that the mains fuse may remain intact.
3.) that if the mains fuse remains intact that the potentially fatal result will be MAINS voltage on the Chassis.

Tief, you have made a grave mistake placing that dangerous schematic on the Forum where every Member can see it.

Please ask to have the dangerously wired pic removed before someone gets killed.
What happens, if the diodes from the pic in post #31 about
Is Gainclone Direct Coupled? Appropriate Preamp?
are not in use, and for the cap only a very small 63V version and for the resistor only 1/8 watts?
If there is a failure, the resistor fired up and the cap explodes (this I observe in several cases - very often by both first Cyrus integrated amps).
But I don't understand, why now the safety requirements are violated. The mains earth is still connected with the metal envelope. Only the PCB-GND isn't now connected with the metal envelope, which serves as a shield against electrical interference.
The only unwanted effect is an audible hum. Isn't it?
Also by shorting of that cap. Now one hear a GND loop hum. Also in this case the mains earth is still connected.
What do I overlooked?

Nevertheless the diodes in this topology seems to be a good solution; until now I know this diode topology by using for a DC Filter - go to
dc filter

Last edited by tiefbassuebertr; 18th June 2012 at 03:37 PM.
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Old 18th June 2012, 03:34 PM   #22
Joschl is offline Joschl  Germany
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What is exactly the problem with the picture in post#1?
The connection to the power inlet is not shown, ok.
But I guess we all connect P1 directly to the chassis. And the pic in post#1 just shows the network between P1 power ground. Two different storys?
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Old 18th June 2012, 03:47 PM   #23
AndrewT is offline AndrewT  Scotland
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The FAULT current cannot flow from Audio Ground to Chassis and thence to PE, because Tief has blocked the route with a 100r resistor.
That resistor will limit the Fault current to ~230Vac/100r ~ 2.3Aac until it blows up. The fuse is unlikely to blow and the Audio Ground will now be sitting at 230Vac until someone touches the speaker terminal or the input terminal or some other bit of connected equipment that is not "earthed".
Once the Fault current route has broken, the equipment becomes a death trap.

Tief should never have posted that schematic on a public Forum. Tief is behaving irresponsibly by leaving the dangerous schematic on this Forum. He was told, but he did not accept advice and here we are thirteen days later and still the dangerous schematic is showing for fools waiting to copy and kill themselves.
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Old 18th June 2012, 03:51 PM   #24
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by tiefbassuebertr View Post
.................... until now I know this diode topology by using for a DC Filter - go to
dc filter
This has NOTHING in common with the DC blocker that can reduce transformer hum due to non symmetric AC waveforms.
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Old 18th June 2012, 04:12 PM   #25
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This is all very exaggerated. A straight connection from the IEC sockets PE pin to the chassis and from there a 10 Ohm/5W resistor paralleled with 100nF 275V X2 rated capacitor connected to audio GND will do the job as mentioned before. Don't use 100 Ohm. And certainly do not connect audio GND to PE directly if you like your equipment to sound good.
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Last edited by jean-paul; 18th June 2012 at 04:21 PM.
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Old 18th June 2012, 04:31 PM   #26
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Quote:
Originally Posted by AndrewT View Post
Tief should never have posted that schematic on a public Forum. Tief is behaving irresponsibly by leaving the dangerous schematic on this Forum. He was told, but he did not accept advice and here we are thirteen days later and still the dangerous schematic is showing for fools waiting to copy and kill themselves.
Why you don't understand, that the circuit from attachement in my post #1 comes not from me ??? - go to
Decibel Dungeon GC w/LM3875
From there I have upload that file.

BTW - I have inform the moderator "SY" from AUSTIN/Texas and ask for instructions to remove this attachment.

Quote:
Originally Posted by AndrewT View Post
This has NOTHING in common with the DC blocker that can reduce transformer hum due to non symmetric AC waveforms.
This I know.
Nevertheless - the topology from diodes of both (DC blocker and the so called "Disconnecting Network") is the same, even if the purpose is completely different.

Last edited by tiefbassuebertr; 18th June 2012 at 04:37 PM.
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Old 18th June 2012, 04:33 PM   #27
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Don't bother. The drawing is good for the discussion about possible side effects. Please note that regulations differ in various european countries. Here devices under 5 VA don't need to be earthed, in Germany 230V AC wiring may be inside plastering without PVC piping which is forbidden here etc. etc. One union but not in electricity. This while we are all connected to the european grid. It seems that in countries where building reliable equipment is difficult most attention is paid to safety regulations Just kidding.

Metal chassis should be connected to PE. That is where the primary concern is. Ground Fault Circuit interruptors will do their job in the aforementioned unrealistic "death trap" scenario. PE was invented to protect us from touching live conductors/wiring/cases under voltage.
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Last edited by jean-paul; 18th June 2012 at 04:52 PM.
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Old 22nd June 2012, 11:35 AM   #28
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Several URLs I have found in this matter by the term "safety earth"

Earthing Your Hi-Fi - Tricks and Techniques
Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
Resistor-GND
a resistor to ground?
Safety Question Concerning GND Loops
Safety question concerning ground loops
Poweramp Starground and mains earth
Poweramp starground and mains earth
connecting audio ground to Safety Earth
connecting audio ground to Safety Earth
Testing low current diodes for fault current survivability
Yet another 3886 gain clone!
Ground Loops Tech Notes
Ground Loops
Breaking The Loop
Solving Computer Audio Problems
GND/Earth Wiring Management by Power Amplifiers - what is the royal Way
GND/Earth Wiring Management by Power Amplifiers - what is the royal Way
http://valvewizard2.webs.com/Grounding.pdf
http://blueguitar.org/new/articles/o...round_loop.pdf
Balanced Connectios by Audio (Jensen)
http://www.aes.org/sections/pnw/pnwr...lock_pnw05.pdf
Star-earthing and "3rd party" Naim power supplies
Star-earthing and "3rd party" Naim power supplies - pink fish media
Mains and Chasis Star Grounding in AKSA 100?
Mains and Chasis Star Grounding in AKSA 100?
Hum on Avondale NCC200 derivative amp
Hum on Avondale NCC200 derivative amp
Starground and mains earth at Gainclone
Building a Gainclone chip amp power supply.
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Old 23rd June 2012, 04:49 PM   #29
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Checkout this also
Quick guide on Grounding
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Old 24th June 2012, 09:24 AM   #30
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Quote:
Originally Posted by OnAudio View Post
Checkout this also
Quick guide on Grounding
Thank you for this URL. Because there are many different headlines to the same topic, there must actually be a lot of more threads here on diyaudio than the previously mentioned from the last two posts.
Here are another examples.
What means ground lift?
Is Gainclone Direct Coupled? Appropriate Preamp?
http://www.diyhifi.org/forums/viewto...=2003&start=15
Gainclone HUM, THUMP problems - The solution
Power Amp build bits - guidance required...

Last edited by tiefbassuebertr; 24th June 2012 at 09:37 AM.
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