[BUILD] 1176LN Rev D DIY

[the groke]

Hi Tzujan,

It sounds like removing more coating from the back chassis ground point won't help your problem. I think you are saying that you don't have continuity between one side panel and the back panel? But even if you lost continuity between one side and the back panel, I would expect that you would still have it via the side panel's connection to the front panel (which then connects to the other side panel and the back). Did you try just tightening the case screws? The insides of the holes are all stripped of coating. I would expect that those connections are contributing to the overall continuity of the case. Or maybe you aren't measuring at a good point on the problem side?

best,

D

 

[tzujan]

D,

I am planning on creating a better connection by grinding a more direct connection between the offending panel and the back/bottom.  It is strange that I cleaned all the holes out, which helped (down to .8) and I woke up the next morning and it was up to 1.4!  So I will get the dremmel out again and see what I can do.

Thanks!
Brian

[/quote]

 

[the groke]

Weird. You could also just join the sides with a wire lead between a couple of screws (one on each panel) I suppose…

Also, I'm curious, is there any buckling on the front panel of your build? No matter how I adjust/readjust the screws on my chassis, the front panel just does not fit correctly. It's like the screw holes are too close together horizontally on the front panel. Consequently, it buckles out a bit. This is of course the least of my worries since I can't even finish calibrating this thing (I do have a couple 5k pots on order though), but still, I would expect that it should be able to sit flat. My unit is from 2010. Maybe Hairball had it re-machined for later kits? Or maybe all of them do this? Or maybe I'm just an idiot and can't screw things correctly?

 

[tzujan]

There was no buckling on the front, and a little more of the dremmel did the trick.  I was able to test the power supply, and I am now filling the PCB.

 

[the groke]

Hey - congrats on solving your issue, and good luck with your build! Don't mix orange and red wires up…. cough cough…

If Hairball audio is out there, could you possibly comment on my front panel buckling issue? Is my case isolated, or were there other reports of such buckling from the early runs of the kit?

Thanks,

DT

 

[EstockAudio]

Hello all!  I've run into a bit of a debacle...

I've been trucking along on my Rev D 1176 build and got all the way through the wiring with no issues.  Everything powers up and looks great, but I've hit a snag at the Gain Reduction Meter Tracking Adjustment calibration step. 

At step 4, I only get 1.3V at pin 2 and 3 of the XLR out with the input cranked.  I've triple checked my resistor values and my wiring.  Everything seems correct.  I should note that the needle didn't drop when I moved the shorting pin back to "normal" position. 

If

 

[the groke]

Hi. I finally got a 5k trimmer to replace the 2k in R44 today (It's not very easy to get parts where I am). But I still can't get the needle to move back up to -10 in the second part of the meter tracking calibration.  There is some improvement. That is, I can now do the back and forth routine with R71 at least once (I can move the needle up to -10 the first time). But then, after adjusting R71, I run out of room on R44 to bring it back up to -10 a second time.

What on earth is going on? Does this signal that my Q12 Q13 transistors are not properly matched? My kit came with a matched pair, so I never actually tested them. I don't really want to take them out to test, since I will probably kill them with heat in the process.

Or will adding a 5k for R71 help? (I can't see why this would…)

I really hope someone can help me on this - I don't know what to do….

Thanks,

D

 

[Echo North]

Weird. You could also just join the sides with a wire lead between a couple of screws (one on each panel) I suppose…

Also, I'm curious, is there any buckling on the front panel of your build? No matter how I adjust/readjust the screws on my chassis, the front panel just does not fit correctly. It's like the screw holes are too close together horizontally on the front panel. Consequently, it buckles out a bit. This is of course the least of my worries since I can't even finish calibrating this thing (I do have a couple 5k pots on order though), but still, I would expect that it should be able to sit flat. My unit is from 2010. Maybe Hairball had it re-machined for later kits? Or maybe all of them do this? Or maybe I'm just an idiot and can't screw things correctly?

We switched manufactures around that time.  This is the first buckling I've heard of. 

Where are you located?  What is your calibration issue?

Mike

 

[Echo North]

Hi. I finally got a 5k trimmer to replace the 2k in R44 today (It's not very easy to get parts where I am). But I still can't get the needle to move back up to -10 in the second part of the meter tracking calibration.  There is some improvement. That is, I can now do the back and forth routine with R71 at least once (I can move the needle up to -10 the first time). But then, after adjusting R71, I run out of room on R44 to bring it back up to -10 a second time.

What on earth is going on? Does this signal that my Q12 Q13 transistors are not properly matched? My kit came with a matched pair, so I never actually tested them. I don't really want to take them out to test, since I will probably kill them with heat in the process.

Or will adding a 5k for R71 help? (I can't see why this would…)

I really hope someone can help me on this - I don't know what to do….

Thanks,

D

Are your voltages checking out in the GR section?

Did the qBias adjustment go ok?

 

[EstockAudio]

Anybody?  This is driving me bananas!

Hello all!  I've run into a bit of a debacle...

I've been trucking along on my Rev D 1176 build and got all the way through the wiring with no issues.  Everything powers up and looks great, but I've hit a snag at the Gain Reduction Meter Tracking Adjustment calibration step. 

At step 4, I only get 1.3V at pin 2 and 3 of the XLR out with the input cranked.  I've triple checked my resistor values and my wiring.  Everything seems correct.  I should note that the needle didn't drop when I moved the shorting pin back to "normal" position. 

If

 

[Echo North]

Anybody?  This is driving me bananas!

Hello all!  I've run into a bit of a debacle...

I've been trucking along on my Rev D 1176 build and got all the way through the wiring with no issues.  Everything powers up and looks great, but I've hit a snag at the Gain Reduction Meter Tracking Adjustment calibration step. 

At step 4, I only get 1.3V at pin 2 and 3 of the XLR out with the input cranked.  I've triple checked my resistor values and my wiring.  Everything seems correct.  I should note that the needle didn't drop when I moved the shorting pin back to "normal" position. 

If

Double check your GR OFF wiring.  I had it messed up in my guide until yesterday.  It's right now.  With GR OFF pad 22 should be connected to black, you can test this with an ohm meter.

If that is wrong fix and recalibrate your Qbias.

 

[Echo North]

If your GR off is ok, did your bias go well?

 

[EstockAudio]

If your GR off is ok, did your bias go well?

The Q-Bias step went fine.  Step three is where things got quirky.

 

[Harpo]

At step 4, I only get 1.3V at pin 2 and 3 of the XLR out with the input cranked.

Maybe misreading your post, but transformer output is floating balanced. Your output is between XLR-pin 2 and pin3 (not between pin2 and 0V or between pin3 and 0V or whatever else reference). XLR-pin1 is connected to chassis/shield in the shortest possible way and is not involved in your measurement.

 

[the groke]

Are your voltages checking out in the GR section?

Did the qBias adjustment go ok?

Hi Mike,

yes, my qBias was successful once I fixed the red/orange wiring mix up on my transformer.

My voltages are in the right ballpark in the meter driver section.

Could it be the matching (or lack thereof) for Q12 and Q13?

We switched manufactures around that time.  This is the first buckling I've heard of. 

Where are you located?  What is your calibration issue?

Mike

It's not extreme buckling, but it definitely is not flat. I can send you a picture if you like.

I am located in Sweden…

Thanks,

DT

 

[Echo North]

If your GR off is ok, did your bias go well?

The Q-Bias step went fine.  Step three is where things got quirky.

With the input and output at 12 o'clock and GR OFF.  what are you seeing between XLR output 2 and 3 feeding a 0dB signal into the input?  You should see something like 10dBu ish which would be about 2.25V AC.  If you continue to crank the output to max you should see as much as 10V.  If increasing the input lowers it your GR OFF in not working. 

Otherwise your gain stage is messed up and we'll start exploring down that road.  Start by checking agains the schematic with voltages on the MNATS site.

Mike

 

[Echo North]

Are your voltages checking out in the GR section?

Did the qBias adjustment go ok?

Hi Mike,

yes, my qBias was successful once I fixed the red/orange wiring mix up on my transformer.

My voltages are in the right ballpark in the meter driver section.

Could it be the matching (or lack thereof) for Q12 and Q13?

We switched manufactures around that time.  This is the first buckling I've heard of. 

Where are you located?  What is your calibration issue?

Mike

It's not extreme buckling, but it definitely is not flat. I can send you a picture if you like.

I am located in Sweden…

Thanks,

DT

It's possible that the hFE is so off on the transistors that they can't calibrate.  I would suspect something else though especially if you tried a larger 5K trim pot.  Q12 and Q13 are not matched,  Q1 and Q10 are.

Are you seeing a 10dB drop at the output XLR?

 

[Echo North]

Yes please send me a pic of the metal weirdness.

 

[the groke]

Thanks  - I will take the pic later today.

I'm confused about this:

Q12 and Q13 are not matched,  Q1 and Q10 are.

In the 1176LN_REVD_V2.2_DOC.pdf it claims that Q12 and Q13 are the matched pair. I don't even think that Q1 and Q10 are the same transistor.

"7 2N3707 TRANSISTOR BIPOLAR Q5,Q7,Q8,Q9,Q10,Q12,Q13 Q7-Q10 HFE >250;Q12-Q13 MATCHED
OR SUB 2N5088 – USE ALTERNATE
BASE PADS ON PCB. REFER
TO DATASHEET FOR PINOUT"

Maybe it's different on one of the other versions????

 

[Unit7]

Thanks  - I will take the pic later today.

I'm confused about this:

Q12 and Q13 are not matched,  Q1 and Q10 are.

In the 1176LN_REVD_V2.2_DOC.pdf it claims that Q12 and Q13 are the matched pair. I don't even think that Q1 and Q10 are the same transistor.

I'm 99% sure Mike meant Q1 & Q11