Stereo 1176 support - Mnats/Hairball

[tonycamp]

There was another member doing true bypass boards with a built in psu.  That is what I put in mine.

This is the one Dan is talking about.

http://www.groupdiy.com/index.php?topic=44049.0

 

[dandeurloo]

Yep!  That is the one.  I think I powered it differently then using the on board PSU.  I can't remember I would have to take my comps out of the rack and look. 

 

[eparg]

Thanks for pointing me in the right direction for the relay! Will begin building later this week 

 

[mltamisin]

OK, so the PSU connection.... if you're facing the main PCB board so you can read the legending (AC, CT, AC), is the right negative and the left positive? Don't want to fry anything.

Figure it out: It's the opposite of what I thought. Lucky I didn't fry anything.

 

[dribro]

hi guy's

How about this one? and it is suitable for various projects. You only have to fit parts accordinly to your supply. I'm gathering parts for my gssl's and the dual 1176.

 

[mltamisin]

Wow, these meters are super bright! I see why the 840 ohm resistor was used. Gonna add some resistance to these.

 

[germoju]

Hi,

here is my Dual 1176 in a a Purusha case (very small !)
Take a look : http://flic.kr/s/aHsjGfrsE3

Everything looks good... same compression response on channel A & B, sounds good etc.
Today I can hear (sometimes...) a noise "hummm" begin at maybe 90 or 100 Hz with some octaves.... The noise comes and disappear.... sometimes he's here 5 secondes, sometimes he's here 3 minutes and gone....
I dont know what's this s##t !
Here is an exemple : http://youtu.be/Isni2B59dE4

Someone has an idea ??

 

[mltamisin]

I reworked the wiring and noticed my +30v rail was slightly high. As I was adjusting R7 (variable trim 5k) I may have fried something. Saw some smoke and R4 & R6 looked fat a bulged out so I replaced them and also installed fixed value resistors in R3 (2.7K ohm) and R5 (840 ohm) instead of the 5k trimmers in case they went out too. Now my rail is reading +35v! 5k trimmers measure out fine. Something else has to be burnt out. Maybe a diode? Would that be visible?
I reordered new 5k trimmers. Can I make a breadboard circuit with 30v and -10 test points to trim out this guy before I connect it to the main PCB? I really don't want to trim out the voltage while it's in circuit.

 

[dacapitan]

When using the external PSU I noticed http://mnats.net/psu.html is using the G1176 board and the Jumpers do not match the parts on M.NATS 1176 rev D 2.2 PCB

I noticed germoju has CR7 going to <+30V (R87) and CR10 going to -10V (CR6)

Is this correct?

I have not been able to find any explicit answer to this.... but I have noticed the question come up, unanswered.

Thanks

 

[hymentoptera]

Hi,

here is my Dual 1176 in a a Purusha case (very small !)
Take a look : http://flic.kr/s/aHsjGfrsE3

...

not sure what's causing the humm, maybe something external, like computer monitor, or...

I just wanted to say that your dualie looks good. I like how the boards are stacked, I was wondering myself if that was possible in a 2RU enclosure. Hope you get the hum issue sorted out soon!

 

[eparg]

When using the external PSU I noticed http://mnats.net/psu.html is using the G1176 board and the Jumpers do not match the parts on M.NATS 1176 rev D 2.2 PCB

I noticed germoju has CR7 going to <+30V (R87) and CR10 going to -10V (CR6)

Is this correct?

I have not been able to find any explicit answer to this.... but I have noticed the question come up, unanswered.

Thanks

I believe you can wire directly to the test points (+30,-10,gnd) without having to jump anything. I could be wrong. Best to check the schematic to be sure. Also verify (beep) with a multimeter.

Hope that helps.

 

[germoju]

Hi,

here is my Dual 1176 in a a Purusha case (very small !)
Take a look : http://flic.kr/s/aHsjGfrsE3

...

not sure what's causing the humm, maybe something external, like computer monitor, or...

I just wanted to say that your dualie looks good. I like how the boards are stacked, I was wondering myself if that was possible in a 2RU enclosure. Hope you get the hum issue sorted out soon!

Thanks... Case is 225 mm large... That´s really small and i had to test a lot of PCB position to reduce the "hummmmm"
that's maybe something external... I hope so... I passed so many times on that machine !!!

 

[germoju]

When using the external PSU I noticed http://mnats.net/psu.html is using the G1176 board and the Jumpers do not match the parts on M.NATS 1176 rev D 2.2 PCB

I noticed germoju has CR7 going to <+30V (R87) and CR10 going to -10V (CR6)

Is this correct?

I have not been able to find any explicit answer to this.... but I have noticed the question come up, unanswered.

Thanks

I believe you can wire directly to the test points (+30,-10,gnd) without having to jump anything. I could be wrong. Best to check the schematic to be sure. Also verify (beep) with a multimeter.

Hope that helps.

Yes yes ....
you can plug directly to +30 and -10 without jumper cause you come from the PSU Board witch gives you the +30V / - 10V.... And that a better solution to avoid jumper...

 

[dandeurloo]

Did you remove the paint behind the switches and pots so they make solid contact to ground?  You don't want them to float. 

Many people have built stereo 1176's into my cases with no noise.  The project is great in a 2u.  My guess is something ground related. 

 

[germoju]

Did you remove the paint behind the switches and pots so they make solid contact to ground?  You don't want them to float. 

Many people have built stereo 1176's into my cases with no noise.  The project is great in a 2u.  My guess is something ground related.

Yes I did remove paint between switches and pots...
Thanks

 

[dacapitan]

When using the external PSU I noticed http://mnats.net/psu.html is using the G1176 board and the Jumpers do not match the parts on M.NATS 1176 rev D 2.2 PCB

I noticed germoju has CR7 going to <+30V (R87) and CR10 going to -10V (CR6)

Is this correct?

I have not been able to find any explicit answer to this.... but I have noticed the question come up, unanswered.

Thanks

I believe you can wire directly to the test points (+30,-10,gnd) without having to jump anything. I could be wrong. Best to check the schematic to be sure. Also verify (beep) with a multimeter.

Hope that helps.

Yes yes ....
you can plug directly to +30 and -10 without jumper cause you come from the PSU Board witch gives you the +30V / - 10V.... And that a better solution to avoid jumper...

Thanks so much for the reply - noted!

I also noticed CR7 & CR10 lead to the AC terminals - hence the reason for jumping from CR7 to <+30V (R87) & CR10 to -10V (CR6) - this is best, in case you are set on using the terminal blocks.

Excuse my n00bish questions (I am a n00b)...... with regards to the LED ratings on MNATS Little PSU ... what are the minimum Voltage and Current ratings required.... I dont want them to burn out!

 

[germoju]

hey !

for the LEDs I used 3mm with resistors values 390R for R1 and 1k5 for R2 

 

[dandeurloo]

Yes I did remove paint between switches and pots...
Thanks

I had lowend noise before I did this and it fixed it for me.  I would say try using a alligator clip and connecting it to star ground and then try testing the pots and switches again and see if the noise drops or changes at all.  Just to be sure to rule it out.  Other wise does it make a difference if the top is on or off of the case?

 

[germoju]

I got a good continuity test between pots, switches and ground...
I will try what you told me...

my ON/OFF switch : http://www.banzaimusic.com/DPDT-on-on-Toggle-15A-250V.html

Other wise does it make a difference if the top is on or off of the case?
I have to test it again cause actually the machine is racked... I will unrack soon to verify...

Today I tested continuity with knobs 's screws. I got 0,4 ohm maximum...
only ratio knobs are 1,9 and the other 1,4 ohm. I will fix this soon...
I can see the noise louder on channel B than the channel A...

 

[dandeurloo]

I just looked at your photos again.  It looks like your wiring to your power switch isn't shielded.  That could be the problem specially if the second channel is noisier then the first.  Try removing it from the front panel and pulling the wires away from the other wiring.  Then carefully check for noise again.  You may need to shield that wiring and so it dumps noise to the star ground and not into your audio.  I do that for all my builds now.

If you do, then I recommend covering the shield with something like shrink wrap.  Then if the power wires break they don't make contact to the shield, and then to the chassis, and then you.