[BUILD] 1176LN Rev D DIY

[ln76d]

hello DIYers !  ;D

I am building a Dual 1176 with Revision D boards and I have a question about ground. In a single 1176 we take the negative C25 to ground. For my project I use the Mnats PSU board to aliment the 2 PCBs, so I dont use C25 cap on PCBs...
So my question is : how to connect mains PCBs boards to ground ?

Thanks a lot !!

Hi,

i didn't found any information about wiring standard rev D PCB, to ground by connecting it to negative on C25. If You can post some link for this i'll be much appreciate. I'm doing dual rev D too, but with two psu from the basic rev d boards.

I've looked on schematic from mnats external psu, and there's a point for grounding.
I think You should use only this grounding point. For other, than PSU, parts of circuit You have few other grounding points. In sum! If You have an extra points for grounding power supply on basic PCB and You're not using this part of pcb, Your new point of grounding this part of circuit is on external psu PCB designed by mnats.
I hope it's understandable, cause my english sucks
Simple version (i hope) - if C25 (You wrote that) is the point of grounding power supply and You not have this part of circuit - You have nothing to grounding.

 

[germoju]

hello DIYers !  ;D

I am building a Dual 1176 with Revision D boards and I have a question about ground. In a single 1176 we take the negative C25 to ground. For my project I use the Mnats PSU board to aliment the 2 PCBs, so I dont use C25 cap on PCBs...
So my question is : how to connect mains PCBs boards to ground ?

Thanks a lot !!

Hi,

i didn't found any information about wiring standard rev D PCB, to ground by connecting it to negative on C25. If You can post some link for this i'll be much appreciate. I'm doing dual rev D too, but with two psu from the basic rev d boards.

I've looked on schematic from mnats external psu, and there's a point for grounding.
I think You should use only this grounding point. For other, than PSU, parts of circuit You have few other grounding points. In sum! If You have an extra points for grounding power supply on basic PCB and You're not using this part of pcb, Your new point of grounding this part of circuit is on external psu PCB designed by mnats.
I hope it's understandable, cause my english sucks
Simple version (i hope) - if C25 (You wrote that) is the point of grounding power supply and You not have this part of circuit - You have nothing to grounding.

I buided 12x 1176 you have to connect the - of C25 to ground. Take a look here : http://mnats.net/1176_reva-d_hairball_wiring_meter_circuit.html

As I use the Mnats Alternate PSU for my first dual 1176 I dont use C25 anymore.... that's why I wonder where ?

 

[ln76d]

I buided 12x 1176 you have to connect the - of C25 to ground. Take a look here : http://mnats.net/1176_reva-d_hairball_wiring_meter_circuit.html

As I use the Mnats Alternate PSU for my dual 1176 I dont use C25 anymore.... that's why I wonder where ?

I don't doubt on C25 connection, but i didn't found before those information, so thank You for the link!!!!!

As i wrote before (if it was understandable ), i think You should grounding only the point "GROUND" from mnats schematic.

http://mnats.net/files/MNATS_PSU.pdf

 

[germoju]

I know you dont doubt... but my english is not so good too I just wanted to explain you that I'm sure about this information, so you have to do it too

If you got trouble for your build .... tell me and I will help as I can

The GROUND on the PSU schematic goes to CT on the main PCB... So I dont need to ground anything else so you think ?

EDIT :
hummm... on that picture I understand COM from alternate PSU goes to CT of first board which is connectec to CT of the other board and that's all.
POS to AC1 with a bridge to +30V (R87)
NEG to AC2 with bridge to -10V (CR6)

http://mnats.net/images/1176_rev_d_dual_inside.jpg

 

[ln76d]

I know you dont doubt... but my english is not so good too I just wanted to explain you that I'm sure about this information, so you have to do it too

So we both suck on english and we both have good intensions

If you got trouble for your build .... tell me and I will help as I can

Thanks, i'm really appreciate!
For now i've stuck on my dual rev d. I'm waiting for enclosure, i need to draw front panel layout for drilling and engraving and i cannot find in Europe f.... frames for sifam al39 meters I soldered pcb sets, measured every transistor (other parts too - i matched almost everything), so probably  per a month i'll do the rest.
If i find something truly hard for me, i'll write to You

The GROUND on the PSU schematic goes to CT on the main PCB... So I dont need to ground anything else so you think ?

EDIT :
hummm... on that picture I understand COM from alternate PSU goes to CT of first board which is connectec to CT of the other board and that's all.
POS to AC1 with a bridge to +30V (R87)
NEG to AC2 with bridge to -10V (CR6)

http://mnats.net/images/1176_rev_d_dual_inside.jpg

I'm glad that You posted this photo link.
My fault! I forgot, that  should go three wires +/CT/-.
I've looked only on mnats external psu schematic.
For me at this picture it goes like this:
- ground from external pcb to main (enclosure) ground
- from first pcb "CT" point to main ground
- from other pcb "CT" point to main ground

Shame that toroid cover those connection, but if looking on green wires bendings and solder point - there goes three wires.

 

[germoju]

yes you're right !

COM, CT (pcb1) and CT (pcb2) are linked to a star ground behind the toroid

 

[zekester]

Thanks for the history of support on this board, incredibly great kit from Hairball, and mnat's excellent reference material! Just completed my first 1176, did a little troubleshooting and got it calibrated. It sounds great and I am actually a little bummed I am done with the project.  Y'all are awesome!

 

[AMaziad]

Just completed my first 1176, did a little troubleshooting and got it calibrated. It sounds great and I am actually a little bummed I am done with the project.  Y'all are awesome!

Do what I did, build a Rev A.  8)

 

[tof]

Hi everyone, i've finished a unit and it works fine(voltages are ok calibration too etc...) except a lowcut appears, is anyone had the same issue??
Any advices??!!
I tried something with balanced and unbalanced output but still the same!
thanks for any help

 

[ffarrell]

HI all:


I've stuffed most of the resistors and low lying parts on these bad boys then I spent most of last night going over this thread that I'm replying to right now without finding out definitive answers to the question below. 

sorry if this has been covered somewhere in this thread.


1. If I want to use the Hairball ( Avel Lindberg 2X25 30VA dual primary/secondary toroidal) power transformer can I just parallel the power outs to the 2 different 1176 D boards with on board power?

2.  I went through forty 3707 last night to sort them into common piles.  measured between 421-429 or  431 - 438.  I measured with a radio shack DDM so i know they are super close .  Is the higher rated one better to use?

thank you
fvf

 

[Echo North]

Hi everyone, i've finished a unit and it works fine(voltages are ok calibration too etc...) except a lowcut appears, is anyone had the same issue??
Any advices??!!
I tried something with balanced and unbalanced output but still the same!
thanks for any help

Do you have the orange and yellow tied together on the output transformer?

 

[Echo North]

HI all:


I've stuffed most of the resistors and low lying parts on these bad boys then I spent most of last night going over this thread that I'm replying to right now without finding out definitive answers to the question below. 

sorry if this has been covered somewhere in this thread.


1. If I want to use the Hairball ( Avel Lindberg 2X25 30VA dual primary/secondary toroidal) power transformer can I just parallel the power outs to the 2 different 1176 D boards with on board power?

2.  I went through forty 3707 last night to sort them into common piles.  measured between 421-429 or  431 - 438.  I measured with a radio shack DDM so i know they are super close .  Is the higher rated one better to use?

thank you
fvf

1. Not sure never tried it.  Give it a go, should work.  Just use a proper fuse to avoid any disaster.

2.  Shouldn't matter.

 

[tof]

Do you have the orange and yellow tied together on the output transformer?
[/quote]

Yes i did(but in case i will recheck this)
Thanks

 

[Echo North]

Do you have the orange and yellow tied together on the output transformer?

Yes i did(but in case i will recheck this)
Thanks
[/quote]

Also make sure you have the output transformer wires in the correct spot and that they are seated correctly if using screw headers.  Keep in mind that the earlier Rev D boards had a different output transformer layout.  If your headers are covering the silkscreen, download the PDF from the mnats rev D site that matches YOUR version of the PCB.  It's written on the PCB and make sure your wires in the right place.

 

[tof]

Hi echonorth and thanks for your concern.
Well every wires from my output transfos are in the right place and are soldered to the board directly like it is said in the mnats pdf(ver 2.2)and the wrirng page.
Do you think it's only a transfos problem or could it be from a capacitor or anything else!??
Anyway thanks again

 

[Echo North]

Hi echonorth and thanks for your concern.
Well every wires from my output transfos are in the right place and are soldered to the board directly like it is said in the mnats pdf(ver 2.2)and the wrirng page.
Do you think it's only a transfos problem or could it be from a capacitor or anything else!??
Anyway thanks again

I highly doubt it's a transformer issue.  Those are very very rare.  The only possibility is that the polarity is flipped in the main out winding.  Try reversing the 5002 secondary (blue and red).

Double check your wiring, specifically the input section, output pot and output transformer.

If you're using anything extra in your signal chain (like a patchbay) don't use it.  Take anything extra out for trouble shooting.

 

[tof]

I have already flipped the output polarity yesterday,i also tryied to cut off the ground from input and outout xlr sockets but nothing changed, output wiring is ok input wiring too,the output pot is wired like in the mnats pages.
the measure and the music through the unit  are from  the output of my souncard.
The sound is ok and pretty good as i expected except of course this shelve in the low range.
My PS voltage are +29.65v and -9.75v all the others voltages in the meter driver and controlamp are pretty close and sometimes matches with the mnats values.
In the preamp stage it's the same and in line amp i have the value on the collector on Q5 and Q6 wich differ from nearly 1V for Q5 and 2V for Q6 compared to mnats!Is this a problem?
On black wire i read 29.6v on brown 26.8v on whitblack 2.34v on whitered 2.27v.Everything looks correct ??
I attached a picture from my measuring!
Do i have to swap something in the primary wiring?????
Thank you very much for yor reply

 

[Echo North]

You could move through the circuit and see where it's happening.  Maybe try a input a 0dB 1K signal on the in an adjust the output so you get 0dB out (compressions off).  Now note your AC voltage with a DMM at + in of the PCB, output pot wiper, output transformer brown and pin 2.  Now switch to 100hz and measure those again.  See at which point the voltage its lower to isolate where the cut is happening.

This is SHOULD work...I hope.

Mike

 

[tof]

Ok,let's see if i understand you,you mean applying a the siganl (1000 then 100Hz)direct on the board pin (+ and -) then measuring between the pin( +in) on the board and the wiper and then the brown and then the output pin 2?  if i'am correct there is a little tiny loss(like 0.02v) on the brown on the wiper they match on the output there's a gain of + 0.23v !
I don't have any good equipment at home for measurement i'll try out something tomorrow with a friend who have generator scope etc...
Do you think it's the first time with this problem i've looked some threads and didn't find any similar!?

Thanks again Mike for helping me!

 

[Echo North]

Not really like that.  It's a simple dirty test.  The 1176 has a fairly level frequency response in the audio band (+/- a couple dB's).  What you're doing is taking a decent DMM (one that can measure AC up to 1K) to see where the loss is.  The AC is the signal.

Apply a 1K signal to the input xlr.  It doest really matter what the output is set to, just don't touch it after you start testing. Put the common of your DMM on ground and set it to AC.  Now check the AC between the + in of the PCB and ground, then the wiper of the output pot and ground, then the brown (primary) of the 5002 and ground and then blue (secondary) and ground.  Not all the voltages but don't worry what they are.

Lets makes some up (again don't worry if yours don't match I'm making these up):

+ on input: 0.15 VAC
Wiper: 3VAC
Brown: 4VAC
Blue/Pin 2: 0.15VAC

Now you change the frequency to 100 Hz.  You should get basically the same voltages.  If the input + is significantly lower (more than a few dBs) you're losing the low end between the XLR and the PCB (T-pad/Tx).  If it's at the wiper, you're losing it in the first amp stage and so on....

Mike

This will isolate where the issue is.

Mike