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

[scott2000]

unit is completely warmed up.

I read this is important because q12 and q13 are sensitive to temp drift and this is why there is a zero adjust for after everything is calibrated.... like you can put your finger on either one and see the meter move,,,,from here...

http://mnats.net/1176_FAQ.html


but if you're not all buttoned up then I can imagine some hokey ground stuff or interference going on????

it was relatively high with 2,8vac.

Supposed to start with .775v at input....not sure why it was high before........ that and the Qbias trim set to ccw or zero.....you may want to test the legs to make sure.........    it's weird because the new version calibration says to start with qbias wide open......

i lowered it to .775 but now i don't get only veeeery little meter movement and i can't even get to zero db by using the adjust trimmer.

like I mentioned, the Hairball method of Qbias is slightly different and doesn't look at the meter yet.....
nput = "24" mid rotation
Output = "24" mid rotation
Attack = full CCW (switched to off position)
Release = full CW
Compression ratio = 20:1
Meter mode = "GR"
Q-bias adjustment = full CCW
Shorting pin in "normal position"  connecting the two pins closest to Q13


Apply a 1 KHz O dBu signal to the input and confirm with your DMM between pin 2 and 3 of the input XLR.  Now move your DMM to the output XLR and measure AC between pin 2 and 3.  Adjust the output control to read +11dBu (2.75 VAC) on your DMM at the output. Slowly turn the Q-bias adjust (R59) CW until a drop of 1 dB occurs, and your DMM reads +10 dBu (2.44 VAC).  This places your gain reduction FET Q1 slightly into conduction.


Then it goes onto the meter calibration........ I think you need a hybrid approach of sorts but who knows....... what gets me is why it isn't working for you the other way....maybe there is a problem but, try the other method too just to make sure ...I think it's safe.....

Calibration

Calibrating your compressor is a crucial step to ensure its proper operation.  There are several ways to complete the four calibrations and I'll provide the way we like to do it here at Hairball, but also present an alternative method shown in the MNATS calibration videos.  Both work well, it's really a matter of preference and equipment.

https://www.hairballaudio.com/blog/resources/build-guides/calibration

I think you should try getting the voltage drop  in the first step then see what you can do next.......obviously pad 22 needs to be jumped to ground when instructions mention attack pot off/ccw.....


oh and swap those 6.8 to where the tants are at 19 and 20....I think it matters.......


just remember when you go to the following  step ===== meter circuit null==== you'll need to move the jumper at r44 to continue....

then you'll put it back for next step and remove 22 to ground jumper...etc...

Hopefully you can get past first step without issues but we'll have to see..

 

[weiss]

thanks man. i think that's gonna take some time. have to order the tants. i'm gonna report back!

 

[scott2000]

Just swap the tants from c3 and c23????

don't need them there

http://library.hairballaudio.com/images/2013/12/IMG_0538.jpg

 

[weiss]

oh yeah. sure. must have mixed it up :

 

[damiangiannis]

Hello all ...Decided to experiment with this project on a slow pace so i have some start up questions...

I 'm tempted to self-etch mnats boards from his site files. Is it a two layer or one ? I see there are a bottom and top layer apart from the layout ...is it importants to etch both sides ? I don't see any tracks/paths on the top layer ...is it there just for the solder points ?

Another question i have is if i could use a daven t-pad attenuator (600:600 20steps/2db)? I 've sourced some for a ua 176 i 'll make in the future . Knowing that the 1176 is an altered version of the 176 i thought they might share the same attenuator .

Gongrats to all the people involed on making this project a reality ! 

 

[scott2000]

If you are planning on DIY even the boards,etc,,, maybe look around at other sites too.....???


I'd like to get involved one day as well and have been lurking a while trying to learn but, at the end of the day, I'll most likely get a couple of boards from Hairball and go that route since there is a lot of support here and on the Hairball site..... and they're pretty inexpensive and look like quality which is nice...

I think you are correct that there are only the solder pads and designations on the top layer of the boards though..... but I personally really don't know much... The pictures everywhere seem to point to just one side.....

All of these threads are loaded with info so maybe a search would have something....

Please keep posting on your progress.... I'm interested in this.....

Good luck!

 

[damiangiannis]

I will surely make an order from hairball as this project can't be done without one...propably some boards too...it just that i'm intruiged to try etching them my self and put my self on a manufacturing learning curve ...As for the solderpoints i'm a little confused because of the too much black on the top layer ...from what i can understand the black means that this area is going to be copper (after etching)...I now lean that the black top layer must be silkscreened for the soldermask ...Only this makes sense to my head.

Any comment on the Davens or Shalco attenuators ? I saw a post on the (old) stereo link topic which a member mentioned about the davens ...

PS. I hope my posts aren't off topic , meaning that they aren't directly relative to the hairball kits  . I'm assuming this topic is generally refering to 1176 rev.A builds.

 

[scott2000]

...As for the solderpoints i'm a little confused because of the too much black on the top layer ...from what i can understand the black means that this area is going to be copper (after etching)...I now lean that the black top layer must be silkscreened for the soldermask ...Only this makes sense to my head.

makes sense to me.....

PS. I hope my posts aren't off topic , meaning that they aren't directly relative to the hairball kits  . I'm assuming this topic is generally refering to 1176 rev.A builds.

I definitely wouldn't say off topic at all!! Totally related.  It just seems to me like, once people are generally finished with their  builds, they sort of move on to other things and leave their questions and answers here in the threads for others to learn from, and aren't really visiting these particular threads looking to help others if that makes sense....

The Hairball kits seem to have more action as far as responses because more are building them and the info is pretty organized on the support pages....

Most of the obscure stuff is here somewhere too but, a bit more difficult to round up from my experience.....

I'm interested in it all too so feel free to update your progress......

Hopefully someone else will have some info for you too.... I know the search function here can be tricky sometimes so make sure you try different key words and orders to better your chances at finding something...... I find that searching Google with Groupdiy included in the topic can bring up stuff here easier than the actual search function here ...lol

like this popped up totally unrelated to the thread but some relevance???

https://groupdiy.com/index.php?topic=2192.0

Good luck!
.....

 

[weiss]

Hey scott,

so i did exactly as you told me, changed the tantalums and then tried the two different versions of qbias adjustment. but i can turn the trimmer R59 as far as i want, the output voltage doesn't decrease. there must be something wrong with that trimmer ???

 

[scott2000]

Did You check resistance of trimmer???? from wiper to either side as well????

They definitely don't like being spun past where they should stop so, could be damaged ....??

 

[weiss]

Did You check resistance of trimmer???? from wiper to either side as well????

They definitely don't like being spun past where they should stop so, could be damaged ....??

seems broken. i get a total resistance of 1k between wiper and one let, the other leg to wiper shows 0hm..
no way of changing resistance. i'll replace that one

 

[scott2000]

seems broken. i get a total resistance of 1k between wiper and one let, the other leg to wiper shows 0hm..
no way of changing resistance. i'll replace that one

That's a good find...one more troubleshooting item crossed off the list hopefully... Just measure the resistance before installing new one. Mike says it's best to set it to the middle when installing so you know which way to rotate it when calibrating...... I'd still probe it just to make certain when you get there..... try not turning it too far next time...lol

One of my buddies and I used to have a saying when we did stuff that wasn't good.....
"Don't ever do that"

I still need to figure out that meter switch deal...

Can anyone answer:

if the rotary meter switch is set to GR off, should pad 22 show continuity to ground?????

 

[weiss]

That's a good find...one more troubleshooting item crossed off the list hopefully... Just measure the resistance before installing new one. Mike says it's best to set it to the middle when installing so you know which way to rotate it when calibrating...... I'd still probe it just to make certain when you get there..... try not turning it too far next time...lol

One of my buddies and I used to have a saying when we did stuff that wasn't good.....
"Don't ever do that"

I still need to figure out that meter switch deal...

Can anyone answer:

if the rotary meter switch is set to GR off, should pad 22 show continuity to ground?????

yeah!  ;D ;D i'm gonna replace that and maybe also the other trimmers (who knows..)
i get the feeling, Rev A is dead 

 

[scott2000]

Hmmm...Yes on the GR off 22 being grounded ????? :-\

And yours does not???

but pad 22 from meter board shows continuity to main pcb pad 22?

And ground from meter board shows continuity to ground on main pcb???

Are there different switches used for the different boards???.... I noticed the original rotary meter board is a bit different than the newer one with respect to the ground pad.......

Either that or you have something broken or goofy somewhere

 

[scott2000]

May have to just trace where your power is goofed...??

Maybe the voltage select switch was messed with??? I'm not sure how that's wired up so, just a wild guess....

Keep us updated....

 

[HosaMogami]

May have to just trace where your power is goofed...??

Maybe the voltage select switch was messed with??? I'm not sure how that's wired up so, just a wild guess....

Keep us updated....

This is the older version with no voltage select switch. At first I thought the lamp blew a fuse, but I checked that and that was fine. I had more so I tried to replace it but it didn't do anything. I almost feel like the power transformer went bad somehow. Seems crazy to me though.

 

[scott2000]

Kids..lol

I left my  son in my truck while I went outside to talk with someone.........left a leatherman in the cup holder......

Still haven't gotten around to replacing  the sliced vinyl.... :-\

I guess you just need to find out where the power stops getting through....... shouldn't be too hard to find the issue....but yeah, sounds weird..... Maybe a missing link to the story.....

 

[MiamiBoy]

How many test points are there, on the latest Rev A board?
i wanna solder all the test pins in.

Thx

 

[vrrs]

Hi there. I have a Hairball 1176 REV A version 1.2.5 that I am trying to diagnose as to why it isn't working. I have made it through the first two stages of calibrating but run into a wall on the last step: meter calibration mode.

I am having a helluva time getting the GR circuit to show me a 10 B drop.  I am able to get the incoming 1 kHz tone (at .775 VAC) and set the output level using the output knob to get 0 VU on the meter while in +4 on the meter selector. 20:1 ratio is selected.  I have the attack fully on and the GR circuit on. When I switch the GR circuit on and off, I get a momentary 2 dB of GR but it quickly resets back to 0 VU. I can't get the 10 dB level difference with the GR circuit in.

The other tell tale feature of my problems is that I can trim the output to give me the 0.774 VAC to measure on my DMM at the output of the compressor but when I have to move the input up to get 2.44 VAC at the output I can only get 1.4 VAC when maxing the input out


What am I missing?

Cheers!
Elliott

 

[Echo North]

Hi there. I have a Hairball 1176 REV A version 1.2.5 that I am trying to diagnose as to why it isn't working. I have made it through the first two stages of calibrating but run into a wall on the last step: meter calibration mode.

I am having a helluva time getting the GR circuit to show me a 10 B drop.  I am able to get the incoming 1 kHz tone (at .775 VAC) and set the output level using the output knob to get 0 VU on the meter while in +4 on the meter selector. 20:1 ratio is selected.  I have the attack fully on and the GR circuit on. When I switch the GR circuit on and off, I get a momentary 2 dB of GR but it quickly resets back to 0 VU. I can't get the 10 dB level difference with the GR circuit in.

The other tell tale feature of my problems is that I can trim the output to give me the 0.774 VAC to measure on my DMM at the output of the compressor but when I have to move the input up to get 2.44 VAC at the output I can only get 1.4 VAC when maxing the input out


What am I missing?

Cheers!
Elliott

Likely a GR amp issue if you can't get proper GR. 

You'll need to run through the troubleshooting guide, specifically testing TP21 for DC, and TP22/CR2 for AC.  TP21 and TP22 are pads 21 and 22 on your PCB. If you have terminal blocks covering the designations, you can reference this doc to see what the PCB looks like under the blocks.

http://mnats.net/files/1176REVA_125_DOCUMENTATION.pdf

You can see 21/22 at the bottom of the PCB.

Trouble shooting doc is here:
https://www.hairballaudio.com/blog/resources/post/fetrack-troubleshooting-guide

Post your findings for #3,4, and 5.  They probably a little lower than what is posted but let's look at those first.

Mike