All things G1176 - the new "repost" thread.

[romeojesus]

no..no ground enforcement yet...
but i am going to add that, too!

christian

 

[Apache5]

Hi guys . My unit seems to run all ok (exept vumeters that i havent yet). Im trying to find the better place for the toroid with no hum. I put on with IN and OUT full CW, without signal IN. Im scoping the output signal direct to my scope. I only see a small signal of 100Hz with a 25mV positive periode of 2ms, and 10mV of 500 KHz hig frecuencies. When I move the toroid arround the signal stays without changes... Its that ok? or I must put in some signal to view the hum problems? i never did a test of that and I dont know how I can do it exactly.... :?

Thanks

Arnau

 

[gyraf]

You will find VERY little difference in hum when moving the toroid transformer around. The trick with moving powersupply transformers around is for standard EI-core transformers that has way higher stray field.

Somewhere here there is a thread about this topic..

Jakob E.

 

[Apache5]

ahh...! thanks Jacob :grin: i look for that thread... I supose that I can place the toroid where I like without diference with hum, cant I?
thanks

Arnau

 

[gyraf]

yep - but still keep it as far away from the pcb as possible..

 

[al_p]

[quote author="romeojesus"]this turns down the hum A LOT...really
[/quote]

cool. thanks for trying that. :thumb:

 

[hitchhiker]

hi,

I've just completed a G1176 and no problems .

I'm using a 1:1 output tranny and getting my +4 output level with the output control in the top 30% of it's adjustment.

There is a hum though.

I'd like to try the cut that Christian did.I'm wondering,
what are the best methods of cutting the trace?

cheers,
Lance

 

[jrmintz]

When cutting the ground trace should the reinforced ground wire be cut as well at the same place?

 

[gyraf]

Seth,

Yes.

Cut the ground at the same spot as the PCB.

 

[jrmintz]

Thanks, Jakob.

 

[hitchhiker]

I decided to try a cut of the trace in a different spot.

My idea was to distance the output transformer ground from the power supply and keep it tied to the input/output cables.

1) cut trace at small point under C15 (cap to in of output tranny)

2) cut on an angle near pin 3 con of output tranny past pins 4&5 to edge
of board leaving equal meat of ground plane each side of cut.

so the ground point of tranny is not close to PS

Result is very quiet. The hiss is far louder than hum.
If I turn up output to full, I still can't really hear a hum .
I have to max my IN fader and Master fader (of console) to hear a 60 cycle hum.

I could see that if I was to properly install this into a box it could be pretty much dead quiet.

BTW I have not connected shields on in/out cables or reinforced the ground plane with the 14 guage wire.

cheers,
Lance

 

[gyraf]

Lance,

Good!

Would it be possible for you to post a drawing of the points in question?

Jakob E.

 

[hitchhiker]

hi Jakob , I just responded to you in the other thread. maybe we should

drop the other thread?

I only have graphics of the board in a PDF.
If you direct me to a pic I'll give it a try.

Lance

 

[hitchhiker]

found one...drew the cuts but I don't know how to post it :?

Lance

 

[daArry]

lance, if u email me it I'll host n post here...

 

[stoff]

This is my first post here on the new Lab...
I have built 4pcs. of G1176. All work fine since the first time powering up!
@ this point I would like to say MANY THANKS to Jakob and all Others for this greate project :thumb:
However all 4pcs. has the hum problem. I was a little bit fustrated. After along time to try different GND solution without sugcess is this solution!!

from Lance:
1) cut trace at small point under C15 (cap to in of output tranny)

2) cut on an angle near pin 3 con of output tranny past pins 4&5 to edge
of board leaving equal meat of ground plane each side of cut.

Now I have 200% NO hum!!!!!! :grin:
I can high recommend this GND solution!!!

I have also the shields on I/O cables floated and the reinforced the ground plane with the 14 guage wire is done.

I'm so happy now :grin: Jupiee!
thanks to all
Stoff

 

[hitchhiker]

3rd time lucky

now I need a drink,

cheers, :sam: :guinness: :sam:

Lance

 

[stoff]

thanks Lance! :thumb:

You are the MAN OF THE DAY or better YEAR!!
take a drink of my bill
:guinness: cheers :sam:
Grz stoff

 

[al_p]

good work guys.
:green: :sam: :guinness:

 

[hitchhiker]

stoff, thanks for giving the cuts a test.

daAry, good of you to offer hosting,thanks. But it was time for me to learn how to post a pic.


Jakob, could we try revision #8 with ;

1) pin chages for BD 139/140 type outputs

2)grnd trace cut ,location(s) of your choice

3)maybe most people want the out tranny reworked for 1:2.
I'm good with the way it is.
(I have a 1:1 in place and will likely try out the original 2:1 )

cheers,
Lance