DCB1 Build

[omishra]

did not understand this about let go grounds.
Any diagram ?

Its simple. I merge grounds of all input left channel from all sources. Carry merged single left ground directly to buffer input. But switch selection only among live wires.
Same for right channel. Buffer merges both channel ground to power supply ground. So no mixing of ground current as power supply ground remains in middle.

 

[jls001]

@Om: when you say merge "grounds" of all left inputs, do you mean the return leads or the shields of the cables?

Also can you please explain further how you isolate the PS ground and signal ground?

Thanks in advance.

 

[omishra]

I will post picture from my B1. Please wait.

 

[jls001]

Made a few improvements to the internal wiring:

Added:
1) power supply earth grounded to equipment chassis. The earth wire was already extended to the R Core transformer, but the earth was not extended to transformer chassis itself as transformer chassis is isolated. So power supply earth was essentially not grounded to chassis. Grounding the power earth to chassis is a good safety practice.

2) OPS PSU ground isolated from chassis ground, while allowing surge current to safely drain off.

3) re-did the return wirings of the three input channels by clubbing all left channel return leads, and not passing it through the source selector switch as I had done earlier. Ditto right channel return leads.

Shields of all signal carrying wires were already grounded to chassis at source end only and kept floating at the destination.

PS: I would like to thank Cranky for guiding me and putting up with my endless questions

 

[manniraj]

That ground isolation circuit is it essential or a direct ground connection to the chassis also is fine.

 

[jls001]

It's better to have the isolation circuit instead of a direct chassis connection.

 

[magma]

First off
You need to understand
That we diyers take things to an extreme level because we can

A proffesional amp maker never use such a ckt since his RCA barrels are simply grounded to the Chasis do as to follow safety regulations

But we
The fanatics that we are mange to use washers and actually isolate the RCA barrel from the cab

So yes manniraj
Most amp makers just connect to Chasis ground directly

They do not have hum issues since they don't have a bunch of wires running around
There's no pickup
Everything I.e all connections are in a printed ckt board

In fact they wouldn't dream of using a two core shield wire at all

A ground reference is important to all ckts

The small ckt shown by josh basically raises the ground by 0.7v or so

 

[quad]

PS: I would like to thank Cranky for guiding me and putting up with my endless questions

"Now that's a name I've not heard in a long time. A long time".

 

[keith_correa]

The small ckt shown by josh basically raises the ground by 0.7v or so

To do this, you just need a diode to chassis. This is not all that circuit does. Check here on what it is for.

 

[magma]

Sir

I wouldn't implement something not knowing fully about it

 

[keith_correa]

Sir
I know exactly what it does
But I didn't know anyone cared for a detailed explanation

I wouldn't implement something not knowing about it b

If you don't explain in detail, how will anyone know whether it would be useful [for them to implement, maybe]? That is why I posted the link so that everyone could read it and decide if it would be useful to them to implement - now or later. And I don't care if most don't care for a detailed explanation - some one out there will care - that is enough reason for details.

 

[omishra]

What Joshua did is correct though it is extra precaution. Now using that loop breaker circuit raises any voltage. No I don't think so. Please read why I am saying so.

There are two different power sources and consumers. 1. Mains which is references with earth ground potential. So you are supplying live wire and neutral. But clean earth ground also supplied for safety which sink any leakage from mains. Thus saving other parties. Power transformer or SMPS is consumer here. All points human touches and mains live goes needs to be earthed.
2. Your local power supply is referenced with transformer center tap or power bank zero reference. This is where all circuitry sinks electronic charges. Actual consumer for this are all circuits.
Can you mix above two grounds? Yes and No.
Yes when earth ground is clean and very low resistance path. It helps syncing induced noise.
No when earth ground is coming from longer distance, shared by multiple equipments and high resistance. This is highly polluted ground and puts unwanted noises into low power ground. You get artifacts in audio output.
Now why to use separate ground for each signal. I call it return path for signal. Ideally when signal passed through wire they flow charges and equal amount of charges returned with supplied return path. This is complete path. No gadget work without complete closed path.
This flowing charges go to sink quickly. But if you merge two grounds aka return paths before ps reference then they come along other flow of charges from each other. Now current depends upon potential of return path which was now having different due to other signals return current. So you obstructed signal path and thus signal.
So we purists think in this way.
I experienced this while designing phono. Small signal easily affected. So PCB keeps separate return paths till big sink called ground.

Shielding signals by Gaussian surface around signal wires is extra precaution but doesn't harm. Twisted signal and return paths also stop leakage into surrounding as magnetic and static fields of reverse flowing currents cancel each other.

Ground loop is already explained by Rod Elliot.
Please forgive me for all above details as I can not explain more simple way.

 

[prasen_b]

I have started my DCB1 build and run into a problem. I am using a R-core transformer of rating 15-0-15 30VA. I am connecting the red, black and green primary wire to live, neutral and earth on the IEC socket. When connected to mains I am getting only 0.24 volts between the white and the blue secondary wires. Is my wiring correct?

 

[saikatbiswas82]

I have started my DCB1 build and run into a problem. I am using a R-core transformer of rating 15-0-15 30VA. I am connecting the red, black and green primary wire to live, neutral and earth on the IEC socket. When connected to mains I am getting only 0.24 volts between the white and the blue secondary wires. Is my wiring correct?

Did you check whether the transformer works properly? I.e. when connected to mains, are you getting > 15v on the multimeter against white - blue (any) wires in the secondaries?

Sent from my Nexus 5 using Tapatalk

 

[omishra]

I have started my DCB1 build and run into a problem. I am using a R-core transformer of rating 15-0-15 30VA. I am connecting the red, black and green primary wire to live, neutral and earth on the IEC socket. When connected to mains I am getting only 0.24 volts between the white and the blue secondary wires. Is my wiring correct?

Your transformer is not connected properly to mains or fuse blown ib IEC socket, if any.

Sent from my E6 using Tapatalk

 

[prasen_b]

Did you check whether the transformer works properly? I.e. when connected to mains, are you getting > 15v on the multimeter against white - blue (any) wires in the secondaries?

Sent from my Nexus 5 using Tapatalk

I checked with mains directly. I am getting around 0.24 volts across the white and blue secondaries. Seems to be an issue with the transformer.

 

[saikatbiswas82]

I checked with mains directly. I am getting around 0.24 volts across the white and blue secondaries. Seems to be an issue with the transformer.

I am afraid the transformer may be faulty. Contact the seller.

Sent from my Nexus 5 using Tapatalk

 

[jls001]

Simple test - check continuity of primary winding using multimeter. It shouldn't be open or zero.

Repeat for secondaries.

If it's short or open, transformer is faulty. Since this is a step down, primary winding resistance should be higher than secondary. The two secondaries must have equal, or nearly equal coil resistance.

If there is a fuse in the IEC socket, do check that too for continuity. But first check if you've inserted the fuse or not.

 

[omishra]

Show top of transformer, you have 2 secondaries. Means 1 blue pair and one white pair. Correct? And you are measuring across either blue or among white.

Sent from my E6 using Tapatalk

 

[prasen_b]

Simple test - check continuity of primary winding using multimeter. It shouldn't be open or zero.

Repeat for secondaries.

If it's short or open, transformer is faulty. Since this is a step down, primary winding resistance should be higher than secondary. The two secondaries must have equal, or nearly equal coil resistance.

If there is a fuse in the IEC socket, do check that too for continuity. But first check if you've inserted the fuse or not.

I am assuming you are asking me to check the resistance across the primary wires (i.e between red and black wires) for finding whether if its open or short. The fuse is fine. I also checked by directly connecting to mains.

Show top of transformer, you have 2 secondaries. Means 1 blue pair and one white pair. Correct? And you are measuring across either blue or among white.

Sent from my E6 using Tapatalk

I have three wires in the secondary blue-white-blue. Its a 15-0-15 30VA transformer. So I am measuring voltage between the blue wire and the white. I get similar voltage between both the blue-white pairs. I believe all DCB1 builds have sourced the R-Core from the same place.