VALab 23 step Attenuator Ground Wiring

[Thebb]

Hoping to get some help on this topic on the site.

After reading that installing this attenuator after I have done the stock attenuator install could be a hassle (since I would need to rewire everything to adjust for the longer wire lengths needed for the VALAb), I decided to do this upgrade from the start.

My PCB board came installed upside down but was able to figure out which hole is what from contacting the vendor.  I'm assuming wires from the RCA jack go into the input connections and the wires to the grids of the input tube go from the output (using same color wires per side).  What I have my doubts on is on the ground wiring. I have two ground connections on the attenuator.  One for each channel (L/R). 

So these are my questions

1) Where should I connect the black wire coming from the RCA jack grounds?
2) Which channel ground should I connect to 3L?
3) Which channel ground should I connect to TRS phone jack?
4) Do I need wire and solder both of my ground holes in the attenuator together?

Also, since this requires longer wire lengths for these connections, is the wire included in the kit enough for these additional lengths or should I run out and get some extra wire?

Any help/input is appreciated!!
Thanks.

 

[grausch]

With the Crack, you can actually ground both left and right channels in the same together. Thus, there is no difference between left and right channel ground once you have done that. I used JamieMcC's crack build as a template for mine, but either of our build logs should show the connection. You will see a short wire connecting the two middle tabs on the pcb.

Once you have connected the 2 grounds, test them with your multimeter, and you should find that both channels are grounded together. Thereafter, it does not matter how you connect your ground wires, you can use any of the of the ground holes (entire outside circle, both top and bottom) for your ground connections. Choose whichever is more convenient for you. My RCA ground went to the top ring as I could keep my braiding together longer, 3L came off the bottom ground closest to it, and I can't remember where my TRS ground came from. I chose somewhere that allowed for proper routing.

I had more than enough wire to rewire with the attentuator. I don't think I needed to even reuse any of the wire I removed when removing the volume pot.

 

[Thebb]

Hey grausch,

Would you happen to have pictures of your wiring?
Thanks.

 

[grausch]

Have a look at my build log. There is a nice pic where you can see all the wiring on the VALab.

http://bottlehead.com/smf/index.php?topic=6597.msg67906#msg67906

 

[Thebb]

So, if I understand correctly, basically connect the two grounds together with a small black wire.  Then I can connect the black wires as per the manual, connecting to any of the dots on the attenuator PCB Board in the circular edge?

EDIT: from your pictures I am not seeing the wire that goes from the attenuator to T3L ?

 

[soundsgood]

I have a Valab and the cb was upside down also. All the ground wires connect to the two solder pads between in/out. I was unable to fit more than one wire into the solder pads, so i soldered a small bare wire hoop to L/R ground pads and soldered the ground wires to the hoop.

 

[Thebb]

I attached an image of what I have so far.

Note: My black wire from the RCA jack grounds is still not connected, and I have not made the connection to 3L and to the "S" TRS jack.

 

[grausch]

Thebb,

When I removed the volume pot, I did not desolder the wire at 3L as it was pretty tough to reach. I then found a spot where I could ground this on the attentuator at one of the holes close to the top plate. Just to clarify this is on the side of the attentuator that actually goes into the top plate. However, I could have used any of the ground holes. My choice was made as I did not want to remove the wire from 3L and could not increase its length to reach the top of the attentuator.

Soldering that wire was tricky, it took several tries until I was happy. Perhaps removing the attentuator from the top plate could have made this easier, but I never tried that. I prefer having the minimum amount of moving parts when I solder and that meant soldering with it mounted.

 

[Thebb]

If I solder a piece of bare wire to the ground in the circular area, make all three connections there, solder and trim off any excess leads. Would that be an effective way of dealing with this?

 

[grausch]

Sorry, I don't follow what you mean with bare wire to ground. The circular rings are both ground for each channel. Once you link the two grounds as you have done, all the outer ring holes are ground.

Thus, you can use any of the holes in either of the outer rings for your ground connections. Again, I am not sure what is meant with the bare wire idea, but you should have plenty of holes to choose from, thus I would use those.

Edit: I guess I see the problem you are running into. There are several solder joints on your outer rings that have 3 of them very close together. If you look at your photo, you will see it on the left and right rings in the same line as your ground wire. Those middle solder joints should have been open, but it looks like VALabs made a mistake there. If you look at my picture you should immediately see the difference. Each ground wire is in its own hole.

I am guessing that you are running out of physical holes to place your ground wires in. You can either try and remove the solder on those joints, but when I was working on it, my temperatures had no impact on those joints at all. Another option would be to see if there are any open ground holes close to the top plates. If you have any there, see if you can get a ground in there.

I can now see why you are considering a hook-up wire, however I do not like the idea of having too many loose wires. It should work, but you would need to ensure that it is properly attached. I would prefer attaching it at 2 points. One potential way might be to remove the sleeving of the wire you used to connect the 2 grounds (the short black one) and use that for all of your ground connections.

 

[Thebb]

Yes, I see what you mean now.  No wonder I was a bit lost.

Thanks for pointing that out.  I will try to remove the solder from the covered ground holes.  If not, removing the nut and checking for any open ground holes on the top plate side shouldn't be too much of a hassle.

Thanks again.