Just ordered my bits from Farnell for the disconnecting networks for my power amps.
Components
2 x 35A Bridge Rectifiers (100V)
2 x 10R Resistors (5W)
2 x 0.1uF Ceramic Caps (50V)
I think I know how to wire these up. I'll post pictures and a wiring diagram to illustrate my approach to the safety earth and star ground.
I keen to make sure I get this right.
Components
2 x 35A Bridge Rectifiers (100V)
2 x 10R Resistors (5W)
2 x 0.1uF Ceramic Caps (50V)
I think I know how to wire these up. I'll post pictures and a wiring diagram to illustrate my approach to the safety earth and star ground.
I keen to make sure I get this right.
I haven't used them, and there is no detectable sound at all even with sources connected and volume at half way (and nothing playing of course).
the Disconnecting Network if needed will have an impact on the sound. That is precisely why it gets fitted.
One can add a switch in parallel to the Disconnecting Network to short out the network to make comparisons.
The switch does not need to be able the pass the kA of possible fault current. The Disconnecting Network is still in place and should be capable of doing that job, if assembled correctly with the correct components.
One can add a switch in parallel to the Disconnecting Network to short out the network to make comparisons.
The switch does not need to be able the pass the kA of possible fault current. The Disconnecting Network is still in place and should be capable of doing that job, if assembled correctly with the correct components.
OK. I assume that you mean something like this?
It would be useful to be able to bypass this unless needed. Any hints on the parameters for the switch? How much current should it be able to pass?
It would be useful to be able to bypass this unless needed. Any hints on the parameters for the switch? How much current should it be able to pass?
A current rating according like the fuse that is protecting the circuit should be more than sufficient.
Well, I've got two fuse ratings to choose from....both slow blow. A 2A and a 3A. I was going to go for the 2A first, based on recommendations I've seen.
This would suggest a 2A switch.
This would suggest a 2A switch.
Refresh my memory on the back/forward diode network thing again, it's been awhile , people still do that now? No modern commercial gear that I know does.
PJPro said:OK. I assume that you mean something like this?
It would be useful to be able to bypass this unless needed. Any hints on the parameters for the switch? How much current should it be able to pass?
Bypass ? I would just delete pending anyone (Andrew?) objects strongly. I think this relates to some unlikely double fault transformer safety condition. (ie total meltdown for an approved, tested, modern, and light duty transformer?) china syndrome circuit anyone😀
Most commercial gear is Class II.infinia said:
This circuit can help against ground loops in Class I equipment. As long as there is no hum without it, it is better to skip the circuit and make a direct connection from audio ground to case, thus to PE. The circuit will isolate ground from chassis/PE for line level signals thus avoid a ground (hum) loop through that path. In case if a fault it provides a path to PE for shorts to ground, so that a short-circuit current can flow and blow the fuses. There is no double fault necessary, just a mains wire that comes loose and touches some conductive part in the audio circuit.infinia said:
BTW,
the switch is sometimes referred to as a ground lift switch.
Note, it does NOT break the route for Fault Current to flow to Safety Earth.
Any other implementation of supposed ground lift switch which breaks the route for Fault Current to flow to Safety Earth is potentially very dangerous.
delete the connection between Safety Earth and the remainder of the circuit at your own risk. Face the consequences if you ever kill anyone by doing so.
Those are your decisions and we cannot stop you doing this.
Do not suggest that anyone on this Forum should consider copying that stupidity.
If instead you meant to say "make a direct connection from the circuit to Safety Earth" then say that.
the switch is sometimes referred to as a ground lift switch.
Note, it does NOT break the route for Fault Current to flow to Safety Earth.
Any other implementation of supposed ground lift switch which breaks the route for Fault Current to flow to Safety Earth is potentially very dangerous.
Infinia.
delete the connection between Safety Earth and the remainder of the circuit at your own risk. Face the consequences if you ever kill anyone by doing so.
Those are your decisions and we cannot stop you doing this.
Do not suggest that anyone on this Forum should consider copying that stupidity.
If instead you meant to say "make a direct connection from the circuit to Safety Earth" then say that.
Uhh... I did say that in my previous post ie earth to chassis connection. I'm just objecting to the wacky network that appeared later.
Why do we need class II equipment in a home appliance. The amp will be safe and there will be NO hum without that "china syndrome" network. I'm certain of that, but the fact that a bypass switch is contemplated means that you are not.
What are the labels for the switch?😉 hahaha
Safe/Unsafe
Hum on/ Hum off
ClassII/ClassI
to make it cheap to manufacture.infinia said:
Because we as consumers vote with our feet, we go out and buy the cheapest we can find even though we know it cannot do the job reliably and that it cannot be repaired economically and that it will be obsolete within weeks (because the next series of advertisement will tell us that). We throw the Class11 product in the bin for someone else to dispose of and buy more cheap product in whatever flavour of the month.
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