Please can you give a look to this Preamp Grounding - Merlin's Medium Gain Pream

[kagliostro]

To fit in a Geloso G1 1020 A I've draw a Layout for the Merlin's Medium Gain Preamp




The Board is obligated to be two rows (Eyelets) and tall 40mm


Pots and Sockets are (and must remain) on the same side of the Board (as in Hoffman Stout)





I think (read Hope) it is correct (the shield of the shielded cable is deliberately connected to pin #3 of V1a - a trick I learned here into the forum)

What I'm asking you for, is if the Ground Scheme is correct for you

Many Thanks for any consideration and/or advice

Franco

[sluckey]

Ground looks good. Pots are wired backwards.

[kagliostro]

Ciao Steve Grazie

Pots are wired backwards.

 

I was looking to this (Number 3 on the left) 



and not to this 




I'm definitely on confusion 


Franco

[sluckey]

The pots in your layout are viewed from the back side and they are wired backwards. The volume pot with the numbered lugs is viewed from the shaft side.

[pdf64]

Rather than a dedicated common line for the controls back to the input, I think Merlin’s methodology would take the common from a control to the cathode of the following stage.

[kagliostro]

Thanks Steve & pdf64

@ pdf64

I've translated what you are saying bu not sure about what you mean

Be patient, can you try to explain me one other time ? (with other words)

Many Thanks

Franco

[pdf64]

Sorry, I meant to clarify.
So the common lug of the gain pot should be wired directly to the common leg of the 2k2 2nd stage pin8 V1 cathode resistor.

And the common terminals of the bass and volume pots should be linked and wired to the common of the following stage (power amp?).

And further apologies for your translator, I use the term ‘circuit common’ or ‘common’ rather than ‘ground’.
I dislike using the term ‘ground’ because I see it causing confusion / conflation between the concepts of ‘circuit common’ and the safety earth chassis connection.

[tubeswell]

Keeping the ground returns physically grouped to be as close as possible to the relevant filter cap node, with only one point of contact to the chassis for the entire ground buss, is good system IMHO YMMV

[kagliostro]

Many Thanks pdf64 & Tubeswell

@ pdf64

Now all is more clear, the thing enlighted me is the explanation about the use of the term Common

and I can follow your explanations in the right way

Obviously also here we have a distinguish Terra e Massa (Ground and Mass), they aren't the same thing but usually speaking we talk about to put (to connect) to ground meaning a common connection on the circuit

@ Tubeswell

In my Layout I tried to connect all at a single point to the chassis, near the female Jack intake, the input female jack intake will be an insulated model

Something like this


About the remaining of the circuit the idea is to don't modify the original of the Geloso connections also if may be the board will be completely rebuild and listen to the amp before to apply other mod

Thanks Again

Franco

[kagliostro]

Better this time ?





Thanks

Franco

[pdf64]

Better this time ?

Did you attach an amended layout? It’s just that I can’t see any difference 

FYI your layout has the input grid stopper at 100k, rather than the 10k schematic value.

[kagliostro]

Ciao pdf64 Thanks

Did you attach an amended layout? It’s just that I can’t see any difference 

Be patient

This is the Layout on the first post of this thread


And this is the Layout attached to post #9


Do you see any difference ? I see it (at input corrected 100p connection and reversed connections on pots)

This is the schematic (no mod on it, it stay the same)


---

FYI your layout has the input grid stopper at 100k, rather than the 10k schematic value.

I see a 10K resistor (Brown-Black-Orange)

What do you see here ?




Do you see they are Brown-Black-Orange & Brown-Black-Yellow on your monitor ?

Thanks Again

Franco

[sluckey]

I was using a laptop when I made those 3 watt resistors. The "3" band looked very orange. But on my desktop computer the "3" band looks gold. I never went back to change that. The controversial "orange" band is the main reason that I switched from the pretty color coded resistor shapes to a single color with the value written on the resistor body. No more confusion!   

[kagliostro]

This days also the guy that has the 1020 A readed on his monitor 100K instead of 10K and ... also I was thinking to swap to numbers valued resistors instead of color valued resistors (same problem two times in the same week isn't to be underrated)

Thanks Steve

Franco

[kagliostro]

Me stupid, pdf64 was surely looking to the ground sistem not the whole Layout

Franco

[sluckey]

Franco, I've updated my Power Resistors shapes library. Orange should now look more like orange. Save the attached and replace your current "Power Resistors.vss" file. *.vss files are probably located in your "Documents\My Visio Shapes" folder.

[kagliostro]

Oh, Many Thanks Steve

Which a kind present

Franco