Little Help Finishing my Green Pre

[clister01]

Hey Everyone,

Thanks for reading. I've got my green pre almost all done. Soldered all the channels, switches, LEDs, XLR connections now it just comes to wiring up the PSU and grounding stuff. If you've got a minute I could use a little clarification on some of the issues I'm having.

1) Grouding issues. Now I think I have a very basic understanding of why things need to be grounded (been reading through the METAs) but I've got a few small questions. Peter was saying in some past posts how he grounds pin 1 I think it is on the XLR connectors. Now my question is pin 1 on the XLR outputs is not connected to anything so I'm thinking I just wire up pin 1 on those and ground it to the chassis. But pin 1 on the input XLRs gets connected to the PCB. So how do I go about grounding that? Or does the PCB take care of it somehow? Is there a connection from the PCB to the chassis ground that I'm not seeing?

2) The power switch. Where/how do people wire this up? I picked up a switch with an LED built in to it from digikey (part number CKN2064-ND). I'm guessing that it's wired between the PSU PCB and the channel PCB but the number of connectors on the switch don't correspond to the number of wires coming into it. I've got 4 connections coming from the terminal blocks on the PSU. +48V, -15V, +15V, Ground. So what goes right to the PCB and what goes to the switch then to the PCBs? I've included some pics at the bottom of this post if anyone can point anything out I've missed.

3) When wiring the toroid to the PCB (I'm using digikey te62043-nd) i've wired the brown and red wires together and then wired them to the ground input on the PCB. Sounds right?

4) Is there anything else besides (I'm assuming) grounding the XLRs to chassis ground that I should be grounding to the chassis? Any connection from the PCB? From the PSU? Thanks so much..

Just getting ready to plug everything in and have it blow up so wooo! Thanks for any help! Peace

switch - http://www.CameronLister.com/pics/DSC00713.JPG
toroid/PSU - http://www.CameronLister.com/pics/DSC00707.JPG
PCB - http://www.CameronLister.com/pics/DSC00715.JPG
XLR/PCB - http://www.CameronLister.com/pics/DSC00714.JPG
[/img]

 

[dissonantstring]

hi clister01,
1) From Peter C. in the Green Pre META pages:

"What I did for my 8 Channel was this :

Connected all the pin 1 of the input XLR together with a solid piece of tinned copper wire. Connect that to the mains star ground

Connected all the pin 1 of the output XLR together with a solid piece of tinned copper wire. Connect that to the mains star ground

The PSU connector will supply the ground to the individual channel boards. The PSU ground will go to the mains star ground.

Pretty quiet unit."

Peter

2) Your power switch is not going to the PCB. Answered this question here:
http://www.groupdiy.com/index.php?topic=5839&postdays=0&postorder=asc&start=105

3)correct. the other two colors (green and blue?) should go to the AC connection to the PSU.

4) The AC inlet ground pin should be grounded to the star ground along with the XLR pin 1 connections.

clister01 wrote:
>>Just getting ready to plug everything in and have it blow up so wooo!

now where's the fun in that? :grin: every person in diy has to have something go "poof" or have some of the magic smoke released or you don't learn. :wink:

hope this helps.
-grant

 

[clister01]

Right. I read that but I was still confused. Is pin one of the input XLR connected to BOTH the PCB and star ground or just to the ground? Thanks!

-Cameron

 

[dissonantstring]

[quote author="clister01"]Right. I read that but I was still confused. Is pin one of the input XLR connected to BOTH the PCB and star ground or just to the ground? Thanks!

-Cameron[/quote]

yes, pin 1 of the XLR would be connected to both the PCB and the star ground. i just run the connecting wire from the PCB mic input (middle conenction) to pin 1 of the XLR and continue the wire to the 4th lug which connects to the star ground. as long as all the grounds connecting to the chassis end up at one point (the star ground). i string all the pin 1s of the XLR connectors together with one wire and connect that to the star ground.

 

[OddHarmonic]

Actually, in Peter's case (and mine, since I followed his lead) The XLR Pin 1 is NOT connected to both the PCB and the star ground. That would void the star ground. If you look carefully at Peter's pics, you will notice that he does not wire Pin 1 from the input XLR to the PCB. The three pin connection to the PCB only has two wires being used, hot (pin 2) and neutral (pin 3). That is what I would reccommend doing.

Andrew

[quote author="clister01"]Right. I read that but I was still confused. Is pin one of the input XLR connected to BOTH the PCB and star ground or just to the ground? Thanks!

-Cameron[/quote]

 

[dissonantstring]

[quote author="OddHarmonic"]Actually, in Peter's case (and mine, since I followed his lead) The XLR Pin 1 is NOT connected to both the PCB and the star ground. That would void the star ground. If you look carefully at Peter's pics, you will notice that he does not wire Pin 1 from the input XLR to the PCB. The three pin connection to the PCB only has two wires being used, hot (pin 2) and neutral (pin 3). That is what I would reccommend doing.

Andrew
[/quote]

hmm, never noticed that. i connected mine and did have a slight hum which i corrected by grounding the output. my unit is dead quiet now. maybe that's why i had the hum in the first place.
why is there a pin 1 connection from the pcb mic input on V14 pcbs?
-grant

 

[peterc]

why is there a pin 1 connection from the pcb mic input on V14 pcbs?
-grant

Basically covering all the bases. Depends on how one would want to wire the boards, the above way is my preferred method.

There was also a recommendation to wire both the XLR pin1's & PSU ground to the case, & the star ground to the case, seems to work as well. I've not tried that one tho'.

Peter

 

[dissonantstring]

[quote author="peterc"]

There was also a recommendation to wire both the XLR pin1's & PSU ground to the case, & the star ground to the case, seems to work as well. I've not tried that one tho'.

Peter[/quote]

Ah, that's what I did. Seems to work for me. Thanks for clearing that up peter! :thumb:
cheers,
grant