[BUILD] 1176LN Rev D DIY

[JuniusRecordingCo]

Q#

E Measured

E Target

E %

C Measured

C Target

C %

B Measured

B Target

B %

11	-0.78			-0.86	-0.9	95.6%	4.61	10.56	43.7%
12	-1.46	-1.52	96.1%	1.89	9.28	20.4%	-0.85	-0.9	94.4%
13	-1.48	-1.63	90.8%	5.35	9.75	54.9%	-0.95	-1.04	91.3%

Wild. Well, make sure you are measuring voltages in GR mode. That will change Q12 and Q13.

I also bought my mouser kit in August of last year.

Yep. Meter is in GR mode. What's the VDC supposed to be at R79? I read 29.32VDC on one side (makes sense: it's connected to the 30VDC rail), and 4.70VDC on the other side.

I've got meter movement in all ratios modes now; despite the low voltage in Q11, 12 and 13, I'm going to try re-calibrating and see what happens.

 

[critterkllr]

So it's got to be something on the meter board, right? But I'm a little worried about the gain staging, too. Seems like there's an awful lot of gain available at ouput (I've almost always got it turned way down), and compression doesn't start until a lot of input is provided.

I've also noticed that the output gain seems to change a lot between 6 and 7 on the release knob. I don't know if this is normal, but it's not like this at all in my plugins.

make sure you have the correct pots for output and release - moving  the release knob should not change output voltage - after changing release, the output voltage should settle (after a few seconds)  to about the SAME value whether fully cw or ccw.

The pots are the correct value. They were the alpha pots from hairball. I also just triple checked all of the wiring and reflowed the solder joints.

 

[critterkllr]

Q#

E Measured

E Target

E %

C Measured

C Target

C %

B Measured

B Target

B %

11	-0.78			-0.86	-0.9	95.6%	4.61	10.56	43.7%
12	-1.46	-1.52	96.1%	1.89	9.28	20.4%	-0.85	-0.9	94.4%
13	-1.48	-1.63	90.8%	5.35	9.75	54.9%	-0.95	-1.04	91.3%

Wild. Well, make sure you are measuring voltages in GR mode. That will change Q12 and Q13.

I also bought my mouser kit in August of last year.

Yep. Meter is in GR mode. What's the VDC supposed to be at R79? I read 29.32VDC on one side (makes sense: it's connected to the 30VDC rail), and 4.70VDC on the other side.

I've got meter movement in all ratios modes now; despite the low voltage in Q11, 12 and 13, I'm going to try re-calibrating and see what happens.

My voltages for R9 show 9.5 and 29.31. Previously, I had similar voltages to you, but something was shorting out the tracking trimpot. After that was cleared up and it sat powered for an hour, everything moved to the correct voltages.

 

[JuniusRecordingCo]

OK. Maybe I had a short in the Attack knob. After moving it a bit, suddenly I have 9.72VDC at R79.

Things are now going along OK: I'm seeing the meter react as I switch the Attack in and out. But, is it possible to have the Ratio board wired backwards? I'm getting more GR (both at the meter and at my DMM) at 4:1 than 20:1. I've checked the leads from the Ratio Board to the MB, and they're correct. Is this a function of the differing thresholds per ratio?

With input set to show 2.436VAC at the output pins 2 and 3 while Attack is fully off, when setting Attack to full on, I get:

20:1 - 1.58VAC
4:1 - 1.05VAC

Weirdly, these values creep up over time. Just a few seconds later, and I'm reading 1.79VAC and 1.09VAC respectively.

At 1.8VDC, the instruction to "readjust the output level control for “0dBu” if necessary" turns into a vicious circle. Lowering the output to reach 0dBu when engaged means I have to raise the Input to get +10dBu when not engaged. I just never see a full 10dB drop. I go from 2.444VAC to 1.820VAC at the outputs with a 20:1 ratio.

 

[critterkllr]

Well, I think I figured out the problem. I somehow managed to mix up 15 and 17 from the output pot. I looked at that wiring so many times it's ridiculous. I also remember specifically telling myself that the connections are not in numerical order before I connected them. This would explain why compression was going down while the output was going up.

Edit: That appears to be it! I left my signal generator at work, so I can't verify calibration just yet, but it is sounding as it should. So, if compression goes down while you raise the level, the output pot is probably miswired.

 

[dbonin]

Things are now going along OK: I'm seeing the meter react as I switch the Attack in and out. But, is it possible to have the Ratio board wired backwards? I'm getting more GR (both at the meter and at my DMM) at 4:1 than 20:1. I've checked the leads from the Ratio Board to the MB, and they're correct. Is this a function of the differing thresholds per ratio?

This is the expected behavior.    This UA blog is excellent and it describes typical features and how they behave (it's for their plugin, but most of the content applies to an actual clone)
http://www.uaudio.com/blog/1176-collection-tips/

I like this page that clearly explains the fixed ratio and why 4:1 compresses more than 20:1 
http://www.axtsystems.com/index.php?option=com_content&view=article&id=54:1176lnratios&catid=34:1176ln&Itemid=62

and of course, the jbl site's version of the manual explains it all as well:
http://www.jblproservice.com/pdf/vintage%20jbl-urei%20electronics/urei-1176lnmanual.pdf
Cheers,
Don

 

[critterkllr]

And the calibration process went smoothly! The compressor sounds and functions great. Thank you Mnats, Hairball, Ed Anderson and GroupDIY for making this possible! This weekend I'll spend some time comparing it to the Warm Audio 1176.

 

[electron monkey]

I am now at the calibration stage, power supply runs perfectly.  Hairball kit

Problem is I had to resolder some of the trim pots, in the first Q biasing pot stage of the calibration and the pot seems to be quite erratic.  One minute I'm getting a good 2.75 on the output voltage, then trying to tinker with the trimpot and suddenly it will drop to 0V, giving it a wiggle will also make the voltage jump around, so could it be heat damage or me turning it way to much.

None of these trimpots (they are the Vishay T93YA202KT20 ones from the Hairball BOM) have a full CW or CCW position and spin indefinitely.  So either I turned it way too much or in the extremely fidgety desolder and resoldering I have damaged the trim pot with too much heat. 

Either way they seem like they need replacing, are there any easy alternatives as Farnell here in the UK don't exactly deal with small orders.

 

[dbonin]

I am now at the calibration stage, power supply runs perfectly.  Hairball kit

Problem is I had to resolder some of the trim pots, in the first Q biasing pot stage of the calibration and the pot seems to be quite erratic.  One minute I'm getting a good 2.75 on the output voltage, then trying to tinker with the trimpot and suddenly it will drop to 0V, giving it a wiggle will also make the voltage jump around, so could it be heat damage or me turning it way to much.

None of these trimpots (they are the Vishay T93YA202KT20 ones from the Hairball BOM) have a full CW or CCW position and spin indefinitely.  So either I turned it way too much or in the extremely fidgety desolder and resoldering I have damaged the trim pot with too much heat. 

Either way they seem like they need replacing, are there any easy alternatives as Farnell here in the UK don't exactly deal with small orders.

These trim pots are difficult to break in my experience - pull one out, test the resistance with your DMM leads on a middle and outside leg  and give the trimmer a spin and observe the change in resistance.
If you see the resistance range somewhere in the range of 10 ohms to 2.2 M  - there are approx 21 turns (+/- 2)  to go from one extreme to the other.

Some of the more expensive trims pots produce a "click" sound when they reach a limit while others simple get "tighter" and harder to turn as they near the extreme limits of their turn position.

Cheers!
Don

 

[electron monkey]

I am now at the calibration stage, power supply runs perfectly.  Hairball kit

Problem is I had to resolder some of the trim pots, in the first Q biasing pot stage of the calibration and the pot seems to be quite erratic.  One minute I'm getting a good 2.75 on the output voltage, then trying to tinker with the trimpot and suddenly it will drop to 0V, giving it a wiggle will also make the voltage jump around, so could it be heat damage or me turning it way to much.

None of these trimpots (they are the Vishay T93YA202KT20 ones from the Hairball BOM) have a full CW or CCW position and spin indefinitely.  So either I turned it way too much or in the extremely fidgety desolder and resoldering I have damaged the trim pot with too much heat. 

Either way they seem like they need replacing, are there any easy alternatives as Farnell here in the UK don't exactly deal with small orders.

These trim pots are difficult to break in my experience - pull one out, test the resistance with your DMM leads on a middle and outside leg  and give the trimmer a spin and observe the change in resistance.
If you see the resistance range somewhere in the range of 10 ohms to 2.2 M  - there are approx 21 turns (+/- 2)  to go from one extreme to the other.

Some of the more expensive trims pots produce a "click" sound when they reach a limit while others simple get "tighter" and harder to turn as they near the extreme limits of their turn position.

Cheers!
Don

Great.  With that ruled out I also found there was likely a short on the Output knob, redone that and now getting 0.3V CCW to 0.6V full CW on the output knob with an input of 0.775V. 

Q bias pot is altering this slightly when turning, so the problem seems to be somewhere else.

 

[electron monkey]

Major problem now, seems the metal ring of Pad 6 on the ratio board has just completely peeled off just from having the cable on it from the output knob.  $3.50 for a replacement and $50 shipping.  Ridiculous.

 

[critterkllr]

Major problem now, seems the metal ring of Pad 6 on the ratio board has just completely peeled off just from having the cable on it from the output knob.  $3.50 for a replacement and $50 shipping.  Ridiculous.

For a pad? Just connect the cable straight to the switch. Or if it connects to a resistor instead, jump it on the back of the PCB with a wire.

 

[electron monkey]

Major problem now, seems the metal ring of Pad 6 on the ratio board has just completely peeled off just from having the cable on it from the output knob.  $3.50 for a replacement and $50 shipping.  Ridiculous.

For a pad? Just connect the cable straight to the switch. Or if it connects to a resistor instead, jump it on the back of the PCB with a wire.

I'll hunt out a schematic, hopefully something is exposed.

 

[critterkllr]

Major problem now, seems the metal ring of Pad 6 on the ratio board has just completely peeled off just from having the cable on it from the output knob.  $3.50 for a replacement and $50 shipping.  Ridiculous.

For a pad? Just connect the cable straight to the switch. Or if it connects to a resistor instead, jump it on the back of the PCB with a wire.

I'll hunt out a schematic, hopefully something is exposed.

Or just look at the traces on the PCB and test for continuity with a DMM. Correct me if I'm wrong, but it looks like it just connects to the resistor right next to the pad. If so, you can just solder straight to the resistor or use a clipped lead to jump it on the back of the PCB.

 

[electron monkey]

Major problem now, seems the metal ring of Pad 6 on the ratio board has just completely peeled off just from having the cable on it from the output knob.  $3.50 for a replacement and $50 shipping.  Ridiculous.

For a pad? Just connect the cable straight to the switch. Or if it connects to a resistor instead, jump it on the back of the PCB with a wire.

I'll hunt out a schematic, hopefully something is exposed.

Or just look at the traces on the PCB and test for continuity with a DMM. Correct me if I'm wrong, but it looks like it just connects to the resistor right next to the pad. If so, you can just solder straight to the resistor or use a clipped lead to jump it on the back of the PCB.

I have an older black PCB but yes from the schematic it connects to the resistor easily.  I hate that though, the rest of the boards haven't failed me yet.

 

[electron monkey]

Edit: Nevermind, found a short on the attack knob. 

 

[electron monkey]

Just got this unit finished. 

Finally found one last intermittent short on the output knob and what not which was causing major calibration headaches.  Works like a charm now,  after all that I somehow want to make another one.

 

[Tedrummerx]

Hey guys,

So I'm working on a rev d that currently passes an audio signal but has no sign of compression. When checking voltages at the gr control amp, Q7-Q10 all have high voltages(around28-29vdc) at each the C,E,B.

Has anyone run into a similar case who can point me in some direction?

Thanks!

 

[critterkllr]

Hey guys,

So I'm working on a rev d that currently passes an audio signal but has no sign of compression. When checking voltages at the gr control amp, Q7-Q10 all have high voltages(around28-29vdc) at each the C,E,B.

Has anyone run into a similar case who can point me in some direction?

Thanks!

Do you have the right value for R51? I would verify all of the resistor values in that section first, then start going through voltages from the psu through the GR section with the schematic handy.

 

[probablyhenri]

Hi,

I'm building my first DIY project ever and have no experience with electronics. I built the power supply of the Hairball 1176 Rev D today and checked every step twice. When i measure the voltages by placing the common lead on the CT of the power connector and the other lead on the -30V mark (near R87), the result is correct. But when I measure at the -10V mark (near CR6) I get a reading of 0,777V DC.

Does anyone know what could cause this incorrect result? As I said, i'm completely new to this, so I have no experience with troubleshooting electronics... Hope you guys can help.

Thanks in advance!