[BUILD] 1176 Rev A - Back to the beginning...

[electrisizer]

I went back and forth, checked wiring, Pcb´s for components, solder joints, voltages referenced to mnats rev a schematics - one faulty voltage at Q4 which measures 4.1V instead of 6.6V?

It seems that we've got similar problems. I've done some looking and it appears that there are several posts of people with a lower than normal voltage on Q4... Still not sure why though.

Do you also have exaggerated needle deflection too? Check out my youtube video in the previous post. What mine is doing in the video doesn't seem normal to me and I'm wondering if your having the same issue.

Yes indeed, the metering in GR mode is behaving the same way, than what is shown in your video....?
Is you unit compressing the audio signal like it should, but just not showing the correct metering?
My unit is only compressing audio signal noticeable when no ratio button is pressed,
if any ratio button is pressed there no compression at all noticeable!? I find this to be very strange, cause it should work the other way round, i guess?

Can anybody tell what a fully working unit is supposed to do, when no ratio button is pressed?

Thanks&regards
Tom

i have the jumping needle too in GR mode... @20 needle jumps to the left, all other buttons needle jumps to the right... it does not affect audio. i think its no fault.

when ratio switch is OFF i have definitley no compression...

 

[electrisizer]

BTW i think this is gonna be my new favorite comp!!! its rocking hard!
thanks to HB and mnats for making this possible 

i made some test files with a rough mix on my desk.
snare and vocals come beautiful...

snare original: https://app.box.com/s/hb28g8f4temmfooqquqh
snare 1176: https://app.box.com/s/208e1ln93gc6oqbh7413

BTW snare was recorded with HB lola pramp


vocals original: https://app.box.com/s/dif9m1wzidiadpbkml21
vocals 1176: https://app.box.com/s/6nhyna0pe5dybegpa123

the only problem - i need some more blue stripes  :-\

 

[hymentoptera]

electricizer, that sounds great! really pulls her voice together, puts it in the mix i guess. she's got a nice voice too!

 

[Pulse River]

Hey everyone,

Thank you for your kind insight, this is my first comp as well as first time posting here.  I searched the previous posts for this same issue and didn’t quite run across the same problem, forgive me if I overlooked it.


I built the Rev A blue stripe,  and the only ratio that works is the 20:1.  (Which sounds fantastic)
The rest of the ratio buttons still pass signal through, although very hot, and quite distorted.  So it sounds more like a distortion pedal than a compressor.

I checked for obvious signs: cold solder joints...etc, even had it in with a pro tech who overlooked the wiring and schematics and it checked out well with him.

Thoughts?????

Thank you so much for any help you can offer

 

[Echo North]

Hey everyone,

Thank you for your kind insight, this is my first comp as well as first time posting here.  I searched the previous posts for this same issue and didn’t quite run across the same problem, forgive me if I overlooked it.


I built the Rev A blue stripe,  and the only ratio that works is the 20:1.  (Which sounds fantastic)
The rest of the ratio buttons still pass signal through, although very hot, and quite distorted.  So it sounds more like a distortion pedal than a compressor.

I checked for obvious signs: cold solder joints...etc, even had it in with a pro tech who overlooked the wiring and schematics and it checked out well with him.

Thoughts?????

Thank you so much for any help you can offer

Something wacky on the ratio PCB?  Maybe a 470Ω and a 47K swapped?  This you quadruple check all of those 10 resistors?

 

[Pulse River]

Hey everyone,

Thank you for your kind insight, this is my first comp as well as first time posting here.  I searched the previous posts for this same issue and didn’t quite run across the same problem, forgive me if I overlooked it.


I built the Rev A blue stripe,  and the only ratio that works is the 20:1.  (Which sounds fantastic)
The rest of the ratio buttons still pass signal through, although very hot, and quite distorted.  So it sounds more like a distortion pedal than a compressor.

I checked for obvious signs: cold solder joints...etc, even had it in with a pro tech who overlooked the wiring and schematics and it checked out well with him.

Thoughts?????

Thank you so much for any help you can offer

Something wacky on the ratio PCB?  Maybe a 470Ω and a 47K swapped?  This you quadruple check all of those 10 resistors?

I just rechecked all the readings quite a few times,
Most everything looks good:
Although R2 and R3 show a reading of .434 Kohm.......is that too low?

 

[Echo North]

Hey everyone,

Thank you for your kind insight, this is my first comp as well as first time posting here.  I searched the previous posts for this same issue and didn’t quite run across the same problem, forgive me if I overlooked it.


I built the Rev A blue stripe,  and the only ratio that works is the 20:1.  (Which sounds fantastic)
The rest of the ratio buttons still pass signal through, although very hot, and quite distorted.  So it sounds more like a distortion pedal than a compressor.

I checked for obvious signs: cold solder joints...etc, even had it in with a pro tech who overlooked the wiring and schematics and it checked out well with him.

Thoughts?????

Thank you so much for any help you can offer

Something wacky on the ratio PCB?  Maybe a 470Ω and a 47K swapped?  This you quadruple check all of those 10 resistors?

I just rechecked all the readings quite a few times,
Most everything looks good:
Although R2 and R3 show a reading of .434 Kohm.......is that too low?

No that's not an issue.

Test your Pad 21/22 readings.  Read here with Steve_H.  You may have to go back or forward a page or two:
http://groupdiy.com/index.php?topic=29981.1340

Pad 22 should be an AC voltage that changes w/ ratio (feed a 1K, 0dB signal)
Pad 21should be an DC voltage that changes w/ ratio

 

[bieckmusic]

Hi everyone!!

I've been using my 1176 Rev A for almost 3 years and it has worked flawlessly.  Love it!!  However, now, the unit works great for about an hour then develops a buzz/hum, like a bad ground but slightly louder and buzzier.  It's clean for the first 45min to an hour then off to buzz-ville...

any thoughts out there would be appreciated.  I'm going to take a look at it this weekend...

Maybe a bad Filter cap somewhere??

 

[Echo North]

Hi everyone!!

I've been using my 1176 Rev A for almost 3 years and it has worked flawlessly.  Love it!!  However, now, the unit works great for about an hour then develops a buzz/hum, like a bad ground but slightly louder and buzzier.  It's clean for the first 45min to an hour then off to buzz-ville...

any thoughts out there would be appreciated.  I'm going to take a look at it this weekend...

Maybe a bad Filter cap somewhere??

My guess would be something heat related.  Some semi conductor.  Is q6 heat sinked?

 

[preampniak]

First time building an 1176 Rev. A.  I've completed the project per the instructions to the dot....I've been unable to Qbias it correctly.  I'm getting signal passing through the unit but it is considerably lower coming out then coming in.  I'm getting a  1k sine wave reading of 0.775VAC on the input XLR but I'm not able to get anywhere close to 2.75 VAC on the output XLR, even with the input and output knobs up all the way.  If i try to Qbias the Mnats way i'm barely able to get my +4 meter to move when I crank the input up. I've checked for continuity between the grounding and everything, and that is good. Any help would be appreciated.

 

[Echo North]

First time building an 1176 Rev. A.  I've completed the project per the instructions to the dot....I've been unable to Qbias it correctly.  I'm getting signal passing through the unit but it is considerably lower coming out then coming in.  I'm getting a  1k sine wave reading of 0.775VAC on the input XLR but I'm not able to get anywhere close to 2.75 VAC on the output XLR, even with the input and output knobs up all the way.  If i try to Qbias the Mnats way i'm barely able to get my +4 meter to move when I crank the input up. I've checked for continuity between the grounding and everything, and that is good. Any help would be appreciated.

Start by checking your DC voltages:
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Then you need to trace the signal (AC) to see where gets too low.

Feed a 1K 0dB signal into the input.  Set your controls mid way, no GR, and test the signal referenced to ground at the XLR pin 2, + in t-pad, +out tpad, + either side of the input transformer, + at PCB input (it's going to go down a lot through these steps, less than 0.1 VAC at the PCB that's normal), - side of C7, and positive of out XLR.

What are your readings?

Mike

 

[preampniak]

First time building an 1176 Rev. A.  I've completed the project per the instructions to the dot....I've been unable to Qbias it correctly.  I'm getting signal passing through the unit but it is considerably lower coming out then coming in.  I'm getting a  1k sine wave reading of 0.775VAC on the input XLR but I'm not able to get anywhere close to 2.75 VAC on the output XLR, even with the input and output knobs up all the way.  If i try to Qbias the Mnats way i'm barely able to get my +4 meter to move when I crank the input up. I've checked for continuity between the grounding and everything, and that is good. Any help would be appreciated.

Start by checking your DC voltages:
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Then you need to trace the signal (AC) to see where gets too low.

Feed a 1K 0dB signal into the input.  Set your controls mid way, no GR, and test the signal referenced to ground at the XLR pin 2, + in t-pad, +out tpad, + either side of the input transformer, + at PCB input (it's going to go down a lot through these steps, less than 0.1 VAC at the PCB that's normal), - side of C7, and positive of out XLR.

What are your readings?

Mike

it reads .595 (referenced to ground at the XLR pin 2, + in t-pad, +out tpad, +) It reads .777 on the input to transformer and .595 on the output of transformer. .595 at the PCB input.  It reads .594( - side of C7, and positive of out XLR.)

 

[Echo North]

First time building an 1176 Rev. A.  I've completed the project per the instructions to the dot....I've been unable to Qbias it correctly.  I'm getting signal passing through the unit but it is considerably lower coming out then coming in.  I'm getting a  1k sine wave reading of 0.775VAC on the input XLR but I'm not able to get anywhere close to 2.75 VAC on the output XLR, even with the input and output knobs up all the way.  If i try to Qbias the Mnats way i'm barely able to get my +4 meter to move when I crank the input up. I've checked for continuity between the grounding and everything, and that is good. Any help would be appreciated.

Start by checking your DC voltages:
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Then you need to trace the signal (AC) to see where gets too low.

Feed a 1K 0dB signal into the input.  Set your controls mid way, no GR, and test the signal referenced to ground at the XLR pin 2, + in t-pad, +out tpad, + either side of the input transformer, + at PCB input (it's going to go down a lot through these steps, less than 0.1 VAC at the PCB that's normal), - side of C7, and positive of out XLR.

What are your readings?

Mike

it reads .595 (referenced to ground at the XLR pin 2, + in t-pad, +out tpad, +) It reads .777 on the input to transformer and .595 on the output of transformer. .595 at the PCB input.  It reads .594( - side of C7, and positive of out XLR.)

How are your DC voltages in the amp sections?

 

[preampniak]

First time building an 1176 Rev. A.  I've completed the project per the instructions to the dot....I've been unable to Qbias it correctly.  I'm getting signal passing through the unit but it is considerably lower coming out then coming in.  I'm getting a  1k sine wave reading of 0.775VAC on the input XLR but I'm not able to get anywhere close to 2.75 VAC on the output XLR, even with the input and output knobs up all the way.  If i try to Qbias the Mnats way i'm barely able to get my +4 meter to move when I crank the input up. I've checked for continuity between the grounding and everything, and that is good. Any help would be appreciated.

Start by checking your DC voltages:
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Then you need to trace the signal (AC) to see where gets too low.

Feed a 1K 0dB signal into the input.  Set your controls mid way, no GR, and test the signal referenced to ground at the XLR pin 2, + in t-pad, +out tpad, + either side of the input transformer, + at PCB input (it's going to go down a lot through these steps, less than 0.1 VAC at the PCB that's normal), - side of C7, and positive of out XLR.

What are your readings?

Mike

it reads .595 (referenced to ground at the XLR pin 2, + in t-pad, +out tpad, +) It reads .777 on the input to transformer and .595 on the output of transformer. .595 at the PCB input.  It reads .594( - side of C7, and positive of out XLR.)

How are your DC voltages in the amp sections?

+29.8, -9.6

 

[hymentoptera]

preampniak, Mike wants you to check all of these voltages one by one, and look for any that are very wrong
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Not just the supply rails. All of them. They should all read within about 10% of the highlighted volts. All voltages are read with black lead from multimeter clipped to negative side of main power supply smoothing capacitors.

 

[preampniak]

preampniak, Mike wants you to check all of these voltages one by one, and look for any that are very wrong
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Not just the supply rails. All of them. They should all read within about 10% of the highlighted volts. All voltages are read with black lead from multimeter clipped to negative side of main power supply smoothing capacitors.

ok...i'm getting a very low signal at Q3 in the signal preamp section...i'm getting 220mv and 7.71v it should be 6.13v and 13.74.  on Q4 i'm getting 1.9v and 14.6v it is supposed to read 6.6v and 13.72....everything else checked out fine.

 

[hymentoptera]

preampniak, Mike wants you to check all of these voltages one by one, and look for any that are very wrong
http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

Not just the supply rails. All of them. They should all read within about 10% of the highlighted volts. All voltages are read with black lead from multimeter clipped to negative side of main power supply smoothing capacitors.

ok...i'm getting a very low signal at Q3 in the signal preamp section...i'm getting 220mv and 7.71v it should be 6.13v and 13.74.  on Q4 i'm getting 1.9v and 14.6v it is supposed to read 6.6v and 13.72....everything else checked out fine.

Q3: What BJT did you use here (3707, 3708, 5088?), different transistors have different pinouts which is why there's 4 holes there instead of three. And did you test the hfe first before installing? what was the hfe? I'm guessing it's hot enough, so maybe an issue with collector resistor R14 (should be 22k, red red black red brown), and check R16 and make sure it's 100k(brown black black orange brown). Did you test all resistors as you installed them? If all resistors and solder joints nearby look good, maybe pull Q3 and try another transistor there.

Q4: I would immediately suspect an incorrect resistor here since this FET is essentially held open a certain amount by the nearby voltage divider nets. R24 and R25 should be 15M (brown green black green brown) and 3.3M (orange orange green gold) respectively, and R26 should be 33k(orange orange black red brown). If these and thier solder joints and the fet's soldering looks good then maybe you got a dud fet?

 

[musicalsl]

Heya. I'm after some help from this amazing forum.

Doing a Rev A build,

I'm going through calibration and when trying to zero my GR meter, with my probes on R74, I can't get R75 to reduce R74 to 0volt.
R75 is having an effect on the vu needle, but not on the voltage of R74
R74 just sits on 0.46

Cheers

 

[Mr.Franky]

Hey,

My build is still not working correctly. My unit sounds very distorted in either GR mode or not. Searched for issues myself, found nothing. Brought it in with a pro tech, who can't seem to find anything wrong. All voltages seem to match the values on the mnats voltage file.


Any ideas please?
Regards,

EDIT: THE FIX FOR MY PROBLEM IS ON Reply #2263

 

[hymentoptera]

Anybody ever try to lower the value of C17 (1uF) or perhaps C19 and C20 (6.8uF), perhaps with a switch to select between normal and LP, to filter out low frequencies in the sidechain?

If so what range of values should work?

Or is this something that needs to be handled actively and not with simple coupling caps?

I've seen pictures of 1176 units with a normalled (switching) jack on the front which apparently allows tapping of the sidechain on an insert basis, presumably with tip/ring carrying send and return or vise versa.

Thoughts? Experience? All comments welcome. -hy