All things G1176 - the new "repost" thread.

[Zee1usa]

Hello Dean ,



Dean Wrote:

Zee1usa has a board with the solder mask, and it appears that he used #12 wire and just tacked it in several places(~8?) around the perimeter where I'm assuming the solder mask was scraped/sanded/filed off.

Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

Dean


No, I did not try it without the Extra perimeter ground wire
I should have, just to see if it would have been ok.

I was thinking ..why not add extra protection. sometimes
even you are trying to improve for the better, it may not be?
I dont think removing the perimeter wire would help any, but
you just never know.

Here is a pic of the perimeter ground on my second G1176
which I am finishing up now.

Z

 

[orson whitfield]

[quote author="deanp920"] So, what wire did you replace with #12?[/quote]

Well the wire I was using before was pedestrian hookup wire :roll: .

Rob Flinn,

Please keep us informed as to the results of your cut near the meter lamp connection when you get to monitor on a better board/situation. I would like to try this too.

 

[deanp920]

deanp920 wrote:
So, what wire did you replace with #12?


Well the wire I was using before was pedestrian hookup wire .

Sorry Orson, I didn't word my question very well. I was trying to determine if it was indeed the perimeter ground wire that you replaced with #12 wire.

Z,

No, I did not try it without the Extra perimeter ground wire
I should have, just to see if it would have been ok.

Oh well, it's no big deal. Surely someone else will come along and let us know sooner or later. Rob Flinn, are your boards from Gustav?

was thinking ..why not add extra protection. sometimes
even you are trying to improve for the better, it may not be?
I dont think removing the perimeter wire would help any, but
you just never know.

I would tend to throw my guess in the same direction. That is a nice looking ground buss.

I'm a bit curious here; on mine, I continued the heavy ground wire all the way to the chassis lug. What did you do Z? Orson?

Dean

 

[Zee1usa]

Hey Dean,

Dean Wrote:

I'm a bit curious here; on mine, I continued the heavy ground wire all the way to the chassis lug. What did you do Z?



I took a 4 inch 18awg from corner of perimeter ground wire
to chassis lug. So to answer your question..No I did not continue
the heavy wire to the lug.

Thanks Dean,

Z

 

[Rob Flinn]

Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

I tried it straight & for me it had a hum issue !

 

[Zee1usa]

Hello Rob,

[quote author="Rob Flinn"]Just how did you do it, Z? Also, Z, did you ever try Gustav's board without the extra ground wire to see if it had an inherent hum issue?

I tried it straight & for me it had a hum issue ![/quote]


I did not try Gustav's board without the extra ground plane.
From what i gather around here, it can help the hum issues.

To add a perimeter ground wire like I did you need to:

1) Get a 12 or 14 awg solid copper wire. I used some leftover wire from an
electrical wiring installation.

2) Bend it into shape around the perimeter as I did in the picture.
You will need to be very careful not to block the screw holes that the pcb mount on.

3) Around the perimeter of the pcb you will notice about 6-8 ground points that you can solder to. you will need to strip the insulation where they will be soldered to the pcb perimeter. You will need to tin the copper wire in the bare spots that you stripped.

4) Solder the wire on which is tricky with just two hands. Sometimes
I put a long solder wire from my mouth, soldering iron in the other and needle nose pliers in the ohter (to hold the hot wire colse to the pcb
until solder cools). Easier said than done.

5) have a :guinness: or :sam: (Two)

:green:

Z

 

[kdawg]

I too am suffering from the hum. But I think I forgot to ground the centre tap, so I'll try that. But is this weird: I have major 60 Hz hum except when I set the OUTPUT knob to around 4! Then it's almost dead quiet.

Here's what I've tried so far (besides the centre tap grounding):
1. Moving toroid - no difference.
2. Isolating 1/4" TRS jacks from chassis - no difference.
3. Removing power jack ground - no difference
4. Unplugging VU meter light - slight difference in hum sound, but same level.
5. This is a dual unit, I tried disconnecting the 2nd channel altogether - no difference.

I have the input ground to chassis, then chassis to outlet. Output ground is shield grounded to PCB only.

I do have Chef's mod on it. No perimeter ground, Gustav rev 7 (?) boards. I'd really like to NOT have to do this if possible, I have 6 boards!

Other than that, unit works great... even stereo linking works w/pin 7 switch.

 

[Rob Flinn]

I too am suffering from the hum. But I think I forgot to ground the centre tap,

The centre tap should be connected to the ground on the circuit board, which in turn is grounded through the input connection to the chassis

 

[orson whitfield]

[quote author="deanp920"] Sorry Orson, I didn't word my question very well. I was trying to determine if it was indeed the perimeter ground wire that you replaced with #12 wire. [/quote] No it wasn't it was the other wires. I am trying to find a place to host pics so I can post them here.

 

[Zee1usa]

Hello Orson,

[quote author="orson whitfield"][quote author="deanp920"] Sorry Orson, I didn't word my question very well. I was trying to determine if it was indeed the perimeter ground wire that you replaced with #12 wire. [/quote] No it wasn't it was the other wires. I am trying to find a place to host pics so I can post them here.[/quote]



www.photobucket.com

 

[orson whitfield]

Okay , here is a closeup of the pins #3 jumpered with the brown wire (perimeter of PCB) soldered to the middle of the jumper wire. Also, there is a wire (also 12 guage) going from there to the bolt fastening the IEC in to the chassis (star ground). Also there is another 12 gauge wire coming from the mains in ground to this point aswell. So there are four connections happening at this point all leading straight to star ground. I remember someone at the old forum showing me pictures of this setup.

http://tinypic.com/1kwup

http://tinypic.com/1kx9h

 

[Zee1usa]

Orson,

You probably already know this, but just in case.

Becareful not to get any metal shavings, metal dust or any thing like that
on your circuit board of your G1176. It can cause a short. I have seen this happen too many times on accident in other electronics devices
being damaged by this.

Cheers.

Z

 

[orson whitfield]

Yeah I know. Now that they are there what is a good way to get rid of them?

 

[Zee1usa]

[quote author="orson whitfield"]Yeah I know. Now that they are there what is a good way to get rid of them?[/quote]


Compressed Anti static spray air in a can from Radio Shack or Office Depot etc. maybe some alcohol on a anti static Q tip?


Z

 

[Zee1usa]

TWINS!!

check em out...

http://www.groupdiy.com/index.php?topic=218&start=30


They are hum free and sounding nice! :thumb:


Z

 

[deanp920]

Hi Orson,

I'm having trouble seeing your pictures..."page cannot be displayed", etc.


Z,

TWINS!!

check em out...

http://www.groupdiy.com/index.php?topic=218&start=30


They are hum free and sounding nice!

That is good to hear!
But I can't see the pics.

I'm just not wired to deal with computers! :roll:

EDIT: Ok, Z, now your pics are there. Yes, those are very nice looking.
Dean

 

[deanp920]

Orson,

Okay , here is a closeup of the pins #3 jumpered with the brown wire (perimeter of PCB) soldered to the middle of the jumper wire. Also, there is a wire (also 12 guage) going from there to the bolt fastening the IEC in to the chassis (star ground). Also there is another 12 gauge wire coming from the mains in ground to this point aswell. So there are four connections happening at this point all leading straight to star ground. I remember someone at the old forum showing me pictures of this setup.

http://tinypic.com/1kwup

http://tinypic.com/1kx9h

Now I see your pictures.

Does this arrangement fix the hum on your G1176? If so, then great...don't change a thing.

However, it concerns me a bit to see you using #12 wire everywhere except for the perimeter ground wire on the PCB...the one place where it is most needed, based on the evidence presented in this thread and on my own G1176's. My guess is that if you had soldered #12 around the PCB and ran that out to the chassis lug along with the AC mains ground, that would be all you'd need.

BUT, like I said, if what you have works, leave it alone.

pins #3 jumpered

Are you talking about XLR pins? :shock: Pins number 3 on the input and output XLR's carry half of the balanced signal and should NOT be jumpered and tied to ground, unless you want the input and output to be permanently UNBALANCED. Pins 1 on the input and output XLR's are the only ones you can legitimately jumper(only if that helps fix the hum); they should already be connected to their corresponding ground pads on the PCB, via the sheild on each cable connecting each the jack to the PCB.

Dean

 

[orson whitfield]

[quote author="deanp920"] Does this arrangement fix the hum on your G1176? [/quote] No not completely.

[quote author="deanp920"]...it concerns me a bit to see you using #12 wire everywhere except for the perimeter ground wire on the PCB...the one place where it is most needed, based on the evidence presented in this thread and on my own G1176's. My guess is that if you had soldered #12 around the PCB and ran that out to the chassis lug along with the AC mains ground, that would be all you'd need. [/quote] I would have rather used #12 AWG but it is very difficult to do given it's thickness.

[quote author="deanp920"] BUT, like I said, if what you have works, leave it alone. [/quote] Well, the hum , as I have said before, is lower a small bit but still there.

I guess I should try to tack on the #12 AWG wire and see if that helps. I am afraid of damaging components though. It takes a little longer to heat up this thick wire and therefore increases heat transfer.

[quote author="deanp920"] Pins number 3 on the input and output XLR's carry half of the balanced signal and should NOT be jumpered and tied to ground, unless you want the input and output to be permanently UNBALANCED. Pins 1 on the input and output XLR's are the only ones you can legitimately jumper(only if that helps fix the hum)[/quote] Well, I have never tried my G1176 powered up wihtout this ground scheme. I can't remember who but someone posted a pic of this scheme I have. I was just following direction. MY BAD I meant to say pins #1 are jumpered NOT #3. Since I don't have a shield connected to the ground pad on the PCB perhaps this is ok.

[quote author="deanp920"] they should already be connected to their corresponding ground pads on the PCB, via the sheild on each cable connecting each the jack to the PCB. [/quote] Next time I'll try this.

 

[kdawg]

*good info here*

Ok - I was able to test out Gustav's Rev 7 boards with and without perimeter wire.

Results:
No perimeter wire - BAD hum, changes strangely with output level control.

Perimeter wire (did not attach to chassis, just a loop around ground solder points) - hum is almost completely gone! Only noticeable at really high output volume, which is louder than I'd ever go w/Chef's mod in place.

So I am extremely thrilled, finally have 6 channels working!

 

[Zee1usa]

Great to hear KDAWG!

This is good info for the others with the hum issue. :thumb:


Wish I had (6) G1176 :wink: