bodega

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #20 on: October 26, 2007, 08:22:21 PM »
Quote from: "peterc"
Your PSU board will need three input connections from the transformer, 2 x AC & 1x GND.

The combined Red/Brown goes to GND & the Green & Blue go to the 2 AC inputs on the PSU board.

Peter


I've spend the better part of the day pouring over different parts of this board (which is really the best thing to happen to DIY, IMO) while working on my 2-ch Green Pre and PSU and this is one part that doesn't make sense to me.

Elsewhere you wrote, concerning the same question:

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


So does that mean that at the point where the Ground from the Xformer enters the PSU you have the 2 wires from the Xformer (in my case anyways: I'm using an Amveco 62043) PLUS a third wire from that spot to the Ground pin on the AC connection mounted in the chassis? That seems strange to me.

Then of course, that AC connector Ground pin (using the Star Ground scheme) would have a connection to all in and out XLR jacks but NOT to the xformer?

Do I follow this correctly? The *electrical* side of audio is a new thing for me... :oops:

Thanks much!
Matthew


peterc

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #21 on: October 27, 2007, 02:46:56 AM »
Mathew

Can you draw a simple diagram? Thx

Peter
If opportunity doesn't knock, build a door.

kato

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #22 on: October 27, 2007, 11:22:52 AM »
Matthew, don't star ground the AC side of the power supply board, just the DC side.   Where you see "AC AC Gnd" on the power supply board, nothing should connect there except the amveco. (please someone correct me if I'm wrong but that's how I've always done it.) You still have to star ground the ground terminal of the IEC power inlet and the DC side of the power supply board.

bodega

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #23 on: October 27, 2007, 02:01:13 PM »
First of all, thanks for the prompt replies.

I think I can sum up my question with: what connects to the AC inlet ground pin?

From what I can tell, it would be:

a) Pin 1 of all XLR inputs and outputs
b) The chassis

However, when I look at this pic:



...it shows three wires going from the transformer to the AC inlet.

According to KingKai, there are just two connections from the xformer:

Quote
Pri: yellow and red to power "neutral"
black and violet to power "hot"


So I guess I'm just unsure of how "Ground" actually gets to the power supply, if it doesn't connect directly with the xformer first.

Does that make sense or should I try to explain it graphically?

3nity

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #24 on: October 27, 2007, 02:17:18 PM »
The power inlet ground joined with the DC ground or 0V and then that was my Star Ground. I did it that way with my Green who's almost complete.

Hope it helps.
Life is a path, death the destination.

bodega

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #25 on: October 27, 2007, 02:22:16 PM »
Quote from: "3nity"
The power inlet ground joined with the DC ground or 0V and then that was my Star Ground. I did it that way with my Green who's almost complete.

Hope it helps.


So, from the "output" side of the PSU (ie. going to the channels) there is one extra wire, which goes from GND to the power inlet ground?

So that GND terminal would have one connection for each channel PLUS a wire going to the AC inlet?

That looks to be a different scheme than the pic above, no?

peterc

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #26 on: October 27, 2007, 02:35:47 PM »
It looks like my preamp...... It is my preamp...

I'll have to check it on MOnday, but it looks like I used the AC inlet as ground. I have actually changed this unit, swapped out the blue transformer for a toroidal unit. I dont think I changed anything further, but I cant recall.

So, in the pic, the star ground is at the AC inlet Gnd pin.

The bare wire buss connects the XLR pin 1's together.

The Green wire from the AC inlet Gnd pin goes to the PSU.

The input XLR Pin1 on both channels goes to the preamp bords via the shield on the blue cable.

I am not sure where the Gnd connects to the chassis, will check the unit.

This preamp is DEAD quiet.

Peter
If opportunity doesn't knock, build a door.

bodega

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #27 on: October 27, 2007, 05:03:10 PM »
Quote from: "peterc"
It looks like my preamp...... It is my preamp...


Yeah - I hope you don't mind being the "textbook" example? :)

Quote from: "peterc"
The Green wire from the AC inlet Gnd pin goes to the PSU.


Ah, but this is where things get confusing for me. It appears that it's not the PSU that connects to the AC inlet Gnd but the transformer, and the Amveco 62043 doesn't appear to have a separate Gnd input.

Quote from: "peterc"
The input XLR Pin1 on both channels goes to the preamp bords via the shield on the blue cable.


Ah, ok! I get that bit now. It looked like you hadn't connected that at all, so (it appeared that) the only Gnd that reached the boards was via the power supply. So, in that pic, between the XLR inputs and the channels you have a red wire, a light blue wire AND the shielding for that (which carries the Gnd), ALL within the darker blue insulation.

Quote from: "peterc"
I am not sure where the Gnd connects to the chassis, will check the unit.


That would be great. I'd be kinda curious to see a pic, if it's feasable....

bodega

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #28 on: October 28, 2007, 12:47:56 AM »
And... actually... on a less theoretical level:

I've finished the PSU and my output voltages are -23.4v/0v/+23.4v/49v. Am I correct in thinking that's total overkill for powering a Green? :)

My cap voltages are -23.4 on both negative caps and +23.4 on both positive caps, instead of +/-21.5v and +/-15v, respectively.

Makes me think of this post:

Quote
i ordered an extra PS pcb from peter, as i'm going to use it to push 24v for another project(i'm sure i'll post a couple times about it). from what i gather all i'll need to chage is a resistor rating. i can figure that out. what i'm wondering about is the 48v. the green pre design uses 15v and a voltage tripler to garnish the 48v. with 24v, i'll need a voltage doubler. is the curcuit much different?


I guess I should have a look at those resistors?

peterc

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #29 on: October 28, 2007, 04:44:48 AM »
What are the voltages before & after the regulators?

Peter
If opportunity doesn't knock, build a door.


kato

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #30 on: October 28, 2007, 09:47:48 AM »
Quote from: "bodega"

I've finished the PSU and my output voltages are -23.4v/0v/+23.4v/49v. Am I correct in thinking that's total overkill for powering a Green? :)


That is overkill. Don't connect power to the preamp board until you've sorted that out or you'll fry your IC's!

Make sure you switch your multimeter to DC instead of AC when measureing at the regulated/DC side of the PSU board. That may sound obvious but it's a common mistake and will give you crazy readings. (I had that problem.)

I've also been thinking more about the pic of Peter's preamp that you posted. The only explanation I can think of is the IEC ground is connected to the blue case as a shield and wouldn't apply with a regular toroid.

bodega

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #31 on: October 28, 2007, 10:04:35 AM »
How silly, I just realised that I swapped the middle 317 and the 337 so I'll obviously have to fix that.

Since I'd already written it out, here are the voltages as measured by me (recommended measurements in brackets) for future newbies that make that mistake:

along the top
+23.7v (+21v)
+46.8v (+42v)
+69.7v (+63v)

before and after the regs
-23.4v (-21.5v)
+23.4v (+21.5v)
-23.4v (-15v)
+23.4v (+15v)

Edit: swapped the regs and, sure enough, everything is looking pretty good on the PSU front. Now on to the one channel I've built....

Kato: I didn't make the AC/DC mistake this time, but I certainly have in the past.  :oops:

bluezplaya

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #32 on: January 22, 2008, 04:06:13 PM »
Peter, I am having trouble determining what value cap goes on the PSU board because it is printed on the board but not labeled on the layout .gif file. And being that the solder holes are in the way, it is hard to determine. It is the non polarized cap just to the right of the LM317 and the 10uf/63v caps. Can you verify what that is?

Thanks,
Adam
Alabama is the only state in the country where the tooth fairy had to file for unemployment.

peterc

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #33 on: January 23, 2008, 01:06:29 AM »
Adam

I dont have a PCB to hand right now, but I pretty sure that it's a .1uF (100nF) cap. I've just checked & it is.

If you go to www.twin-x.com  & search for peterc album, there is an overlay & BOM there.

Regards
Peter
If opportunity doesn't knock, build a door.

CJ

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #34 on: January 23, 2008, 04:15:32 AM »
OK, Mars Mariner, invention of the ****** toroid,


col mc lymnan, JPL,

first correct ans gets buck
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

kato

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #35 on: January 23, 2008, 11:14:32 AM »
Quote from: "peterc"

If you go to www.twin-x.com  & search for peterc album, there is an overlay & BOM there.


BOM lists 1000uF rated at 10v.
Is this enough?

peterc

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #36 on: January 23, 2008, 01:47:08 PM »
10v is too small, should be 25v or 35v.

Peter
If opportunity doesn't knock, build a door.

kato

Toroidal hook-up (Green Pre) -- Please Help --
« Reply #37 on: January 23, 2008, 05:05:21 PM »
Quote from: "peterc"
10v is too small, should be 25v or 35v.

Peter


I put 50v in those spots.
I was mostly alerting people that that BOM is skedanked.
(I assume you didn't make it.)
It also specifies an electrolytic in the .1uF spot.

I'll just pipe down and post my mouser order from several months ago. That might actually be helpful.

dig it:
271-220-RC
271-2.2k-RC
271-8.2k-RC

647-UVZ1H102MHD (or 647-UVZ1H102MHH)
647-UVZ1J100MDD
647-UVZ2A470MPD1TD

581-BF014E0104J

583-1N4007-B
583-BR31
512-LM337T
512-LM317AHVT


 

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