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

great thanks...

it scared me since it doesn't look like the other 2 pots... may be i uncovered it when unsoldering the pot

but bad news is the 5k pot seems broken...  I see no reading change when i trim the screw...  >.<

thanks

Hairball Audio said:

Nope that is supposed to be connected.

That's how you make a variable resistor with a potentiometer.

Mike

Click to expand...

I have a problem understand the guide on wiring the attack pot,

the text and picture showing in a way that is some how different with the graph on pins A, B, C...

which one should I follow?

( for  example the green is connecting to pin B in the picture but its on Pin C  on the graph...)

zylvia said:

I have a problem understand the guide on wiring the attack pot,

the text and picture showing in a way that is some how different with the graph on pins A, B, C...

which one should I follow?

( for  example the green is connecting to pin B in the picture but its on Pin C  on the graph...)

Click to expand...

http://mnats.net/1176_reva-d_hairball_wiring_attack_release.html
The photo is correct.

Sorry that is fixed now.

I'm reading 6.5 volts off q10 when it should be around 14. R42 is reading 4.5 volts on the q9 side and 23 volts on the q8 side. I've double checked all the components in the gr control amp and there all correct. I'm getting 9.7 and 29.6volts off the power supply section.
What my unit is doing is passing audio but there is no reduction of gain when I turn the gr on. Any suggestions?

njschultzy said:

I'm reading 6.5 volts off q10 when it should be around 14. R42 is reading 4.5 volts on the q9 side and 23 volts on the q8 side. I've double checked all the components in the gr control amp and there all correct. I'm getting 9.7 and 29.6volts off the power supply section.
What my unit is doing is passing audio but there is no reduction of gain when I turn the gr on. Any suggestions?

Click to expand...

If you're sure your wiring is correct.  Triple check Pad 19, 21 ,22 and 18.  That section has a lot of 4.7K, 470Ω and 47K resistors, make sure you did not mix any up.  That would cause what you're seeing.  Particularity R36, R38, R39.  Cap polarity of course.

If all else fails new transistors in the section, but I would suspect that last.

I spent days to read through the posts here but cannot find thr reason of my problem on my Rev A yet..

I checked the wiring many times and past the 3 steps calibration, Input/output pots working well

but I got 2 problem:

1: GR meter working correctly when I turn on attack pot CW, but I dont hear any effect from the output signal

2: When I turn down the release pot (CW to CCW),  the GR meter  drops from 0 to -10..

is there anyone have experience or idea on these?

thanks...

Hi, i've just finished my 1176 RevA  ;D and i really wanted to thank all of you !   

Of course i've encountered some(a lot !! issues and of course, as it said in the beginning of page 1 of this topic, i've been reading almost the 100 pages to find ways to continue the job. Here are the details, so maybe it will help a few (i hope)

-I thought my first issue was the calibration step 2 when i couldn't null the TP10-TP11 to 0vDC! so i've double checked the Pcb, the wire, everything and found that 2 of the R44 pins were making contact. At this point i tried to uncontact these 2 pins and finally get this contact off....but of course that was not a good idea  .....

-so after that and a lot of forum reading, i realized that i wasn't doing calibration step 1 in a right way. As the "populating Pcb" chapter says i pre calibrated all of the bourns trimmers to 1k and i didn't want to go full CW as the calibration step1 says...once i've done this, guess what ? calibration step 2 was successfull too!!!

-but of course in calibration step 3, this bloody R44 trimmer couldn't make the Vu needle move  and this is the point when i understand that this weird contact between 2 pins of this R44 trimmer is normal  :'((page 109 of the topic i think, thank you zylvia !!)

so this morning i 've soldered a wire to make these 2 pins happy and everything was fine, even the calibration step 3!!

i've been checking the voltages all along the building and calibration process and it has helped me a lot to be almost sure my problem was in the GR Pcb section, around Q12 and Q13 and now that everything is ok, the voltages are too!!

one last thing was a weird noise and Vu peg that my output knob created at 9 or 10 o'clock and i found the answer in mnats faq, just had to get the output wire away from the Pcb....

well, my RevA is fine, took me a week to complete this but i'm really happy, i think i've understood a lot of things doing this for the first time instead of recording or mixing, so....
Thank You Guys  8)

[sub][sub]hope my english is readable....

I try to do the calibration again, and I may need to make sure how can I set the "Q-bias adjustment = full CCW"? ( Q-bias calibration)

since I would break the adjust pot if I over rotate according to the guide?

zylvia said:

I try to do the calibration again, and I may need to make sure how can I set the "Q-bias adjustment = full CCW"? ( Q-bias calibration)

since I would break the adjust pot if I over rotate according to the guide?

Click to expand...

Listen carefully while turning and as soon as you hear a click, stop turning

Unit7 said:

zylvia said:

I try to do the calibration again, and I may need to make sure how can I set the "Q-bias adjustment = full CCW"? ( Q-bias calibration)

since I would break the adjust pot if I over rotate according to the guide?

Click to expand...

Listen carefully while turning and as soon as you hear a click, stop turning

Click to expand...

Zylvia, the click method will feet with bourns trimmer (i had to change R44 trimmer with another brand and it doesn't click)
if you put tour DMM on pin2 & 3 of the output XLR, AC volt, you will see the voltage going up if you turn the trimmer. don't be scared it will be like 6 or 7 V! Once the voltage don't move, that's it, it is full CCW.

thanks  Unit7 and French

how about "connecting the two pins closest to Q13"?

I connected the pad 22 and 16  according to the guide video, is that the same thing?

it can be done by simply turn the attack pot off (Full CCW) ?

zylvia said:

thanks  Unit7 and French

how about "connecting the two pins closest to Q13"?

I connected the pad 22 and 16  according to the guide video, is that the same thing?

Click to expand...

zylvia said:

it can be done by simply turn the attack pot off (Full CCW) ?

zylvia said:

thanks  Unit7 and French

how about "connecting the two pins closest to Q13"?

I connected the pad 22 and 16  according to the guide video, is that the same thing?

Click to expand...

Click to expand...

Did you solder the 3 pin header and it's jumper just close to r44 ?
You just have to move the jumper to activate/ desactivate it...
On when jumper is close Q13
Off when jumper is far from Q13

zylvia said:

I spent days to read through the posts here but cannot find thr reason of my problem on my Rev A yet..

I checked the wiring many times and past the 3 steps calibration, Input/output pots working well

but I got 2 problem:

1: GR meter working correctly when I turn on attack pot CW, but I dont hear any effect from the output signal

2: When I turn down the release pot (CW to CCW),  the GR meter  drops from 0 to -10..

is there anyone have experience or idea on these?

thanks...

Click to expand...

IF you know your resistor color-codes by heart, check all resistors, carefully, one by one, and check them all twice.

Many times problems like to this turn out to be misplaced resistors. Even if you think you've got them right, check them again.

Also, check your voltages again using the voltage sheet "1176REVA_125_VOLTAGES.pdf". If any are way out, they you're on to something and narrowing it down.

Zylvia that really sounds like a wiring problem to me.

Mike

Agreed. Perhaps post high res photos, w/ good lighting, of the wiring in and out of the release pot, etc. Maybe something obvious will stand out to one of us.

I know people say pics don't help, but a good number of problems have been spotted or at leat narrowed down this way.

thanks everyone, i think i misunderstood the QBias test  in some point,  i got the compressed signal now,  and release control works well

next will be the attack time control, seems not effect execpt on and off now, sounds like only have the fastest attack when i test with some kick signal...  ( ratio control working good)

will keep working on it

zylvia said:

thanks everyone, i think i misunderstood the QBias test  in some point,  i got the compressed signal now,  and release control works well

next will be the attack time control, seems not effect execpt on and off now, sounds like only have the fastest attack when i test with some kick signal...  ( ratio control working good)

will keep working on it

Click to expand...

Attack on the 1176 is 20-800 MICROseconds (0.00002 - 0.0008 seconds).  Pretty hard to hear unless you're using something very fast to compress like a kick or snare.

Hey All!

I have just built a Hairball 1176 Rev A. Build/Calibration went smoothly.

My problem is when running signal through the unit the output is very thin. Spectral analysis shows a low end roll off from 200Hz at about 6dB per oct.
The output freq. is the only symptom. Compression works and sounds great (when I eq the low end back in).

I have checked the Mnats voltages and all except for Q4 are correct.

G: 1.91
S: 4.07
D: 13.32

Could this be a faulty J309? Could it be responsible for the bass roll off?

Thanks!
-Bob