how do I lift/not lift earth

[frank2395]

My mono blocks are to dificult to get into, 40 screws in total and work ok so I want to leave the amps alone;

My earth loop breaks when I lift one earth to amps.

I want to keep both chassis corectly earthed.(not one corect and other through an IC)

What can I put into my earth line that will allow it to flow when there is an emergancy but break the loop under normal curcumstances.

I can break into my earth wires (power cords) and but a box into the lead with components.

Can I put a rectifier (diodes) or a thermistor (inrush) in series with the wire to break the loop but give me protection

Will this work and or other sugestions please.

 

[kilowattski]

No, unfortunately any ground loop breaking device (thermistor or opposing parallel diodes) should be inserted between your signal ground and chassis ground, inside your chassis. The connection between earth and your chassis must remain unimpeded for safety's sake.

 

[frank2395]

I was hoping that would NOT be the answer, Thanks for your knowledge, I will just have to do the amps

 

[dnsey]

Why not lift the earth on one (or both) of the signal inputs?

 

[frank2395]

cables are non screened, negative carries signal return and is needed

 

[pinkmouse]

Try it, you might be suprised!

 

[frank2395]

Attention Kilo and Pink Thank you ....but

Thanks so far.....but
the amps are silent without the loop,

Thanks Pinkmouse I think it is preferable to leave the return as apposed to using a long and possable dirty earth as my return (your opinion please)

Mr Kilowattski, is it better to have my earth interupted by the diodes or thermistor (to break loop) than to have no earth safety at all (your opinion please)

 

[kilowattski]

Frank,

I like the diode approach because the chassis can never have more than a 0.7 volt difference of potential from ground. Go to the passdiy.com website and look at the Zen IV .pdf file. You can see how it is implemented by looking at the power supply schematic in the Zen IV .pdf file.

 

[frank2395]

Mr. Pass and Mr Kilowattski

Mr Kilowattski,
Thank You,
following on from your comment in relation to mine:

I will break the earth wire in my power lead and insert a rectifier 35 amp +- in~~ out.

The amps will not be touched

Is there an advantage in http://sound.westhost.com/earthing.htm
method with a resistor and capacitor, I will not be having the conection to the chassis as he has but only have this circuit in the power cord

your opinion Mr K and please also Mr pass if you read this

 

[kilowattski]

Frank,

Negative on that one. The chassis must make direct connection to earth ground. If the path is interrupted, even by diodes you have a safety issue. The diodes must go between your amplifier ground and the chassis. Here is the diagram.

 

[jh6you]

Kilowattski

Your example of internal circuit and wires looks never touching the chassis in any case. If so, why the ground line is to go to the earth...?

Regards
jH

 

[kilowattski]

JH,

Does this make it a bit clearer?

 

[jh6you]

Yes.

But, I mean if any current carrying material does not touch the chassis, I could safely touch the chassis with no earthing, could't I...?

Regards
jH

 

[kilowattski]

JH,

Absolutely, but without the chassis connected to earth there are some seroius safety concearns.

 

[frank2395]

Thanks Mr Kilo,
let me put this to you

many sugest and do lift there earths or use a cheater plugs thus no safety

is this not worse than the diodes only in the earth line where some safety is still there (I am trying to keep an avenue of safety rather than lifting all together and only breaking the loop under normal operating conditions)

also your opinion re the extra resistor and cap in the sugested circuit

 

[kilowattski]

Thanks Mr Kilo,
let me put this to you

many sugest and do lift there earths or use a cheater plugs thus no safety

is this not worse than the diodes only in the earth line where some safety is still there (I am trying to keep an avenue of safety rather than lifting all together and only breaking the loop under normal operating conditions)

also your opinion re the extra resistor and cap in the sugested circuit

Using the diodes is absolutely safe because your chassis is directly grounded to earth and the potential between your chassis and your power supply ground can never be more than 0.7 volts, but this should be enough enough to break your ground loop. I don't think the capacitor and resistor solution is particularly safe either. They used to manufacture radios and amplifiers like this in the old days and if the capacitor shorts you have a tremendous shock hazard. They stopped using that method years ago because of the hazard it posed. Nelson Pass uses this scheme in the Zen IV power supply. On higher power amplifiers and tube amplifiers the supplies can be 80 volts and up. If the chassis is not grounded and your power supply is isolated from ground, and God forbid, one of your power supply wires touches the chassis, the chassis could float at whatever voltage the power supply is. If you happen to touch the chassis at that time, wamooo! You would get a healthy shock. This is serious stuff. Here in the US, any product with a metal chassis that is not connected to earth would never recieve a Underwriters Labs certification and probably not be on the market for long. IMHO anyone who defeats the connection between chassis and earth ground is foolish because there are safer ways to deal with a hum problem, even on a commercial product. I know this is not what you want to hear, but if you used a cheater plug to disconnect earth ground from your chassis, the risk is yours, and if something were to happen, you only have yourself to blame.

 

[frank2395]

therefore....

Mr Kilo,
therefore let me sum up from best to worst.

amplifier has star ground conected to earth conected to chassis (sealed and untouched in the next sinarios)

a) power cable from power supply has full earth conected from power supply to IEC amplifier socket

Power plug -----------------------------------(earth)------amp socket

SAFE AND CORECT

b) power cable earth has diodes in line with power supply and IEC amplifier socket

Power plug------------(diodes)------------(earth)----------amp socket

SEMI SAFE AND NOT TOTALY CORECT

c) power cable has no earth conection
UNSAFE AND NOT CORECT


I am hoping I can use b

 

[AudioFreak]

Re: therefore....

I am hoping I can use b

No.

 

[kilowattski]

Frank,

Choice "B" should be power cable earth ground wire connects directly to the chassis and back to back diodes connect between your power supply ground and the chassis. I suggest you use a 35 amp, 600 volt bridge as your diodes.

 

[frank2395]

ok I have tried everything to convince you otherwise but to no avail

I have been despirate to use b with the diodes just breaking the earth wire but you will not let me.

I did not want to open my amplifiers and connect diodes between earth with chassis and star ground but you leave me no choice.

You are all a bunch of Bas......s but I love you

Thanks all for your appreciated help and advice and I will open the amps.