[BUILD] 1176LN Rev D DIY

[Steventje123456789]

Hello, i recently finished my building of the 1176 rev D. I started at the calibration and came across following problem, step 1 and 2 where not a problem to calibrate but when coming to step 3 i can't get no more than 4 db gain reduction. And when the video of the calibration said : when your drop is lower than -10 db turn up the input pot to lower it to - 10. I did that but it Sems not to work when turning it up the needle Goes to 0 instead of lower. I am in a hope of finding some one who can help me since I would love to start using the compressor.

Kind regards

Steven

 

[andyfromdenver]

Simply wanted to say hi and thanks for making this available.
Ordered all my parts and look forward to the build.



*update*
Completed this evening and calibrated.
Wow!!  Sounds great   thank you mnats and Hairball (and anyone else involved I apologize for not naming)
Wish it were easy to post pics from iPhone here....
I named mine Patrick Squeeze-y...

 

[rjd2rjd2]

Grounding help on my 1176 Rev D build:

when i plug an AC cord into my units, there is a very loud ground hum that is introduced to the output jack. my DC voltages are correct at the PSU, and i have the - lead of C25 tied to the output transformer chassis solder wire, and the rest of the power wiring looks to be right per the build notes. if i lift the output XLR pin 1 from this tie point, the ground gets worse.

any ideas? thanks for the help!

 

[dbonin]

Are you sure you have continuity from all parts of the case (front, sides and back) to ground?
Is there continuity  from the metal case of the input transformer to ground?
There should be no wires that cross over the PCB board (to be safe).

If you have done the above already and everything looks normal,  search back through the rev D thread and you'll find lots of past users with HUM issues and how they solved the problem.

 

[rjd2rjd2]

dbonin-THANKS! solved it. i had checked all of the continuity on grounds, overlooking the XLR input jack to case. once this was solved, i've got a nice quiet wiring. however, i'm still not passing signal, so i'm now going to pursue the probing. question:

should i be signal tracing with the power on, or off? and can i do it both by sending signal to the input AND the output? thanks for the help!!

 

[Echo North]

dbonin-THANKS! solved it. i had checked all of the continuity on grounds, overlooking the XLR input jack to case. once this was solved, i've got a nice quiet wiring. however, i'm still not passing signal, so i'm now going to pursue the probing. question:

should i be signal tracing with the power on, or off? and can i do it both by sending signal to the input AND the output? thanks for the help!!

Power on.  Signal at the input.

 

[dbonin]

I start with power OFF - check that your input signal is making it to the point where the input transformer connects to the main PCB. 
If it is, turn on the unit and start tracing.
Look for the OBVIOUS FIRST - if you are using terminal block connectors, double check that each wire is actually secure. (This is my favorite thing to screw up when I'm in a rush!)
If you have already tried the Q-Bias calibration step already, make sure you have not turned the r59 trimmer so far to the extreme that no signal is passing.  When starting the q-bias step you want to START by setting the trim resistor to allow the maximum amount of signal to pass (ie lowest resistance).

The signal tracing method using a test tone and a speaker really does work.

dbonin-THANKS! solved it. i had checked all of the continuity on grounds, overlooking the XLR input jack to case. once this was solved, i've got a nice quiet wiring. however, i'm still not passing signal, so i'm now going to pursue the probing. question:

should i be signal tracing with the power on, or off? and can i do it both by sending signal to the input AND the output? thanks for the help!!

 

[AusTex64]

I bought a Hairball Rev D build with a GR meter driver problem. I've successfully completed Q bias and meter null calibrations. All looked OK and behaved as expected. (I've built a Hairball Rev A bluestripe kit already).

On the GR meter calibration, I can't adjust the meter to zero with R44.  With max resistance the best I can get is -3db. Jumper is in correct position (trimpot is in circuit). I put a 33K resistor in series with the trimpot, which will get the meter to zero but the meter doesn't accurately show gain reduction when GR is switched in and out of circuit (only goes to -5db when it should be -10dB).

I have the unit set up with 1kHz 0.775VAC input test tone, input/output set to -10db gain reduction when GR circuit is engaged, as per GR cal instructions. Checked all resistors in GR section, they look correct. Checked voltages around transistors per the schematic with recommended voltages, some look a little high (+10%) but pretty close. Replaced Q12 and Q13 with known good 2N3708 with exactly matching HFE (!). Readjusted the GR test conditions to get -5dB gain reduction, when GR is switched into circuit meter goes from -3dB to -8db, so response is linear with 2K R44 at max - just won't adjust up to zero.

I own an electronic repair shop and had my best guy look at this today. Third guy to confirm all parts are in their proper places. We even pulled up one end of the resistors in the GR section and confirmed the values. He thinks the problem is the 2N5457 JFETS aren't matched. Your thoughts?

Thank you in advance!

 

[tomas1808]

Is it ok to wire the VU meter backwards? Will the responde be affected?

I am planning on building a stereo 1176 and I want to place the meters opposite to each other like in the Chandler TG1.

http://chandlerlimited.com/wp-content/uploads/2012/12/chandler_tg1_limiter_01.png

Thanks!

 

[Echo North]

Is it ok to wire the VU meter backwards? Will the responde be affected?

I am planning on building a stereo 1176 and I want to place the meters opposite to each other like in the Chandler TG1.

http://chandlerlimited.com/wp-content/uploads/2012/12/chandler_tg1_limiter_01.png

Thanks!

The VU can be wired backwards, it doesn't really have polarity.

 

[Echo North]

I bought a Hairball Rev D build with a GR meter driver problem. I've successfully completed Q bias and meter null calibrations. All looked OK and behaved as expected. (I've built a Hairball Rev A bluestripe kit already).

On the GR meter calibration, I can't adjust the meter to zero with R44.  With max resistance the best I can get is -3db. Jumper is in correct position (trimpot is in circuit). I put a 33K resistor in series with the trimpot, which will get the meter to zero but the meter doesn't accurately show gain reduction when GR is switched in and out of circuit (only goes to -5db when it should be -10dB).

I have the unit set up with 1kHz 0.775VAC input test tone, input/output set to -10db gain reduction when GR circuit is engaged, as per GR cal instructions. Checked all resistors in GR section, they look correct. Checked voltages around transistors per the schematic with recommended voltages, some look a little high (+10%) but pretty close. Replaced Q12 and Q13 with known good 2N3708 with exactly matching HFE (!). Readjusted the GR test conditions to get -5dB gain reduction, when GR is switched into circuit meter goes from -3dB to -8db, so response is linear with 2K R44 at max - just won't adjust up to zero.

I own an electronic repair shop and had my best guy look at this today. Third guy to confirm all parts are in their proper places. We even pulled up one end of the resistors in the GR section and confirmed the values. He thinks the problem is the 2N5457 JFETS aren't matched. Your thoughts?

Thank you in advance!

If the FETs cam from me they'll be matched unless they became damaged at some point or we really messed up.  I believe you ordered new FETs?  Try that and post back if it doesn't fix the issue.

 

[tomas1808]

Thanks!

 

[AusTex64]

I bought a Hairball Rev D build with a GR meter driver problem. I've successfully completed Q bias and meter null calibrations. All looked OK and behaved as expected. (I've built a Hairball Rev A bluestripe kit already).

On the GR meter calibration, I can't adjust the meter to zero with R44.  With max resistance the best I can get is -3db. Jumper is in correct position (trimpot is in circuit). I put a 33K resistor in series with the trimpot, which will get the meter to zero but the meter doesn't accurately show gain reduction when GR is switched in and out of circuit (only goes to -5db when it should be -10dB).

I have the unit set up with 1kHz 0.775VAC input test tone, input/output set to -10db gain reduction when GR circuit is engaged, as per GR cal instructions. Checked all resistors in GR section, they look correct. Checked voltages around transistors per the schematic with recommended voltages, some look a little high (+10%) but pretty close. Replaced Q12 and Q13 with known good 2N3708 with exactly matching HFE (!). Readjusted the GR test conditions to get -5dB gain reduction, when GR is switched into circuit meter goes from -3dB to -8db, so response is linear with 2K R44 at max - just won't adjust up to zero.

I own an electronic repair shop and had my best guy look at this today. Third guy to confirm all parts are in their proper places. We even pulled up one end of the resistors in the GR section and confirmed the values. He thinks the problem is the 2N5457 JFETS aren't matched. Your thoughts?

Thank you in advance!

If the FETs cam from me they'll be matched unless they became damaged at some point or we really messed up.  I believe you ordered new FETs?  Try that and post back if it doesn't fix the issue.

Got the FETs today and installed them, did not fix the problem. Guess it's time to check every component in this build. Any ideas where to start?

FWIW, I don't think this is Hairball's fault, it's the "tech" that built it. Just regretting buying this thing, much better idea to just build my own. The bluestripe kit I built worked perfectly from the start.

 

[Echo North]

You could try hitting all of the solder joints in that section to try and eliminate a cold joint.

Which voltages are a little high?

 

[dbonin]

Quick RATIO button test to make sure you are getting the right values from your ratios before you wire everything up.
The values will be different for a rev D, but you get the idea!  It's a simple check that can save you a headache later.
ratio button resistance test
After placing resistors and soldering the radio buttons to the board, test the resistance between pads 6 and 4 while cycling through the four radio buttons
REV  A
ratio  Ohms
20:1  47.2k
12:1  115.5k
8:1  171.4k
4:1  227.3k

http://youtu.be/YyR4vZIDNb8

 

[Herbert]

Problems with calibration step 1

I´ve send a 1khz 0,775 VAC in and just got around 30m VAC at the xlr ouput no matter how much I did on the pots.
When I move the T-Pad,the signal on the input xlr changes around 0,03 VAC.

I checked the signal after the input transformer with t-pad fully CW and just got 0,435 VAC

When sending audio signals in,I can only hear high frequencies.

After that,I recognized that 3/4 of my resistors showing really bad values on the main pcb - Instead of the power section where I get a really precise 30V DC and -10V DC rail.

so....something went wrong...

...I guess that it´s not only the resistors....

Idea: I´ve caused some terrible feeedback during the calibration,maybe this was too much....

 

[AusTex64]

<You could try hitting all of the solder joints in that section to try and eliminate a cold joint.>

Good advice. I retouched every solder joint in the GR section, and also removed the GR "0" set trimpot and tested it too, works fine, reinstalled. Even confirmed continuity between every soldered connection in the GR meter driver!

<Which voltages are a little high?>

I'm getting 11.37VDC instead of 10.56VDC on Q11. Since the meter is driven by a differential voltage, all that seems to matter is the differential between X and Y.
The GR meter voltages are +/-10% out in several places with R44 in circuit, but look perfect when it's not in circuit (null mode). And I'm able to null the meter perfectly.

I'm starting to suspect the problem is not in the GR meter driver, but the voltage Q11 is being sent by the GR control amp via R56. What voltage should I be seeing at R65 or Q11 when in GR mode with no input? Just to be 100% sure, I went through the meter null and Q bias adjustments again, confirmed they are all done correctly. Seems like I have to turn up the input pretty high to get -10dB GR with a 0.775VAC 1kHz test signal. It's on 9 (in between 6 and 12). Did the exact same test on my bluestripe. I'm getting -10dB GR with the input on 17. Output on both units is almost the same (48).

I've confirmed all the resistors in the GR control amp and meter driver are correct. Have not checked out the ratio board though. I can't find a drawing of that PCB or a pic online unstuffed, so I can see what the values are supposed to be on the PCB. That would be very handy at this point.

Any other ideas where I should look? Thanks!

 

[rjd2rjd2]

OK-first off, thank you guys SO much for helping us all out with our 1176s!

so i got both of mine working, and passing signal. i got thru the 1st two steps of calibration, however, i'm not having problems. 2 questions:

1-if i sweep my release pot from L to R, i get a huge sweep on the meter. even at GR, it will sweep from full L to pegged in the red. is this normal?

2-in step 3, when i disengage the comp(i've got the attack pot "off" function; should i be doing the 22 pad jumper to ground thing as well?), and the input level is set to 0, i get NO drop in DBs on the meter. it stays at 0. what am i doing wrong here? no combination of pad 22 jumper and comp disengaged will show a drop of 10db, not even 2db!

thanks again for the help, getting close!!!

 

[Mr.Franky]

Hey guys,


I just finished building a Rev D a few days ago. It worked perfectly ofr about 2 days, but now when I fired it up, the VU meter light bulb doesn't seem to work. The sound still sounds the same though. Nothing else weird going on so I suspect it's just the light bulb? How can this get broken by just sitting there? Would there be something wrong with my wiring? I would suspect not.. How can I fix this? Add 2 colored leds at the back of the VU meter?


Thanks in advance! I'll be buying some more kits in the near future for sure!


Mr.Franky

 

[Echo North]

OK-first off, thank you guys SO much for helping us all out with our 1176s!

so i got both of mine working, and passing signal. i got thru the 1st two steps of calibration, however, i'm not having problems. 2 questions:

1-if i sweep my release pot from L to R, i get a huge sweep on the meter. even at GR, it will sweep from full L to pegged in the red. is this normal?

2-in step 3, when i disengage the comp(i've got the attack pot "off" function; should i be doing the 22 pad jumper to ground thing as well?), and the input level is set to 0, i get NO drop in DBs on the meter. it stays at 0. what am i doing wrong here? no combination of pad 22 jumper and comp disengaged will show a drop of 10db, not even 2db!

thanks again for the help, getting close!!!

1.  No that's wacky.  You should see a little movement but not that much.

2. When you switch the attack pot to GR off you are putting pad 22 to ground.  No need to do it again.

Do you have the shorting pin back in the normal position?