[BUILD] 1176LN Rev D DIY

ah, i missed read the first post about the noise.  i thought it was from something that wasn't right and that was leading to overly normal high output.

as for calibration, i re-did steps 1 and 2 and can get very close to 3 being right on.

on step 3, with the attack on, seeing 0.775 on the out, the neddle hits the 0 in '10' but i can't get it to the line.  i run out of trimmer.  it feels like i just need a tiny bit more.

denov said:

ah, i missed read the first post about the noise.  i thought it was from something that wasn't right and that was leading to overly normal high output.

as for calibration, i re-did steps 1 and 2 and can get very close to 3 being right on.

on step 3, with the attack on, seeing 0.775 on the out, the neddle hits the 0 in '10' but i can't get it to the line.  i run out of trimmer.  it feels like i just need a tiny bit more.

Click to expand...

Make sure you are not trying to do the adjustment all in one go.  Start with both centered. and anticipate how they interact.  Some time you have to adjust R44 past or short of 10, knowing that then adjusting the zero will center it.

Mike

Hairball Audio said:

Make sure you are not trying to do the adjustment all in one go.  Start with both centered. and anticipate how they interact.  Some time you have to adjust R44 past or short of 10, knowing that then adjusting the zero will center it.

Click to expand...

oh, i've tried that...  i've tried at least  6 times now.

when i start getting close turning up either R44 or the front panel trimmer both seem to move the needle in the same direction.    to get it as close as i have it i have the R44 almost max CW and front panel max CW.

before I start adjusting the trims I need to repeat steps 4 and 5 a couple times to get the in out out voltages to be correct. 

FIXED

It was the Q bias adjustment. The pot was not centered before the adjustment and it was causing too much gain reduction - after correcting the Q bias, I now have full GR functionality.....

Until I was switching between ratios and turning the unit on and off during tracking/zero adjust and the 1176 will no longer power on. It's dead. I turned it off, then hit the 4:1 from the 20:1 switch and then turned it back on and that's when it died.

I'm freaking out man.

Hairball Audio said:

justinheronmusic said:

No Gain Reduction at 20:1 Ratio

Stuck on 3rd Calibration step. Tried searching through the forums and I can't seem to find any clear solution to this issue, there are also a lot of dead links and the GroupDiy search isn't working (I think it's a website issue)

With attack fully CW:
I've got GR/Voltage drop at the output XLR with Ratio @ 4:1
As I move up the ladder, I get less and less GR/Voltage Drop.
At 20:1 Ratio I have absolutely no voltage drop/GR at the XLR output

I can do all the other calibration steps, it's just this meter issue revealed that there isn't any GR at 20:1 so I know something is wrong. Where should I be looking? What should I be checking?

Click to expand...

The threshold decreases as you go from 4 to 20 so your GR will decrease.  Keep in mind ratio is not overall compression.  Can you get compression at 20:1 if you increase the signal and output?

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You turn GR on and off (via the attack) for the measurement.  Not the unit itself.

Check your fuse.

Mike

After the tracking and zero adjust calibration using the attack knob, I powered the unit down. The next day I powered it on along with everything else in my studio. Thats when I noticed that the zero adjust was way off from when I calibrated it. Hence me turning it on and off several times and switching between ratios - then nothing - no power. Just me with my head in my hands feeling like a complete failure of a human being.

Swapped fuse for fresh fuse - nothing. Tested a new fuse for continuity based on your instruction to previous posters, popped it in, and switched the ratio from 4:1 to 20:1 before powering on, and then let it rip. Good to go. Everything is solid and working properly. Finished up calibration, gain reduction sounds fantastic; another 1176 built and ready to make some art!

I read pages 234-238 and it helped me shine some light on the fuse issue. The 250mA seems to be working for now, but I'm going to order the 400mA just to avoid future issues with it. Sorry to be reposting issues that were already addressed.

I hadn't realized that the meter is heat sensitive, and that the calibration is best done about 45 minutes after powering on. Haha, then after it powers on it takes a little while for that meter to stabilize.

Hairball Audio said:

You turn GR on and off (via the attack) for the measurement.  Not the unit itself.

Check your fuse.

Mike

Click to expand...

denov said:

i can get calibration steps 1 and 2 done.  i run out of trimmer for step 3.

the sound is coming from board. if i press on the pcb with a screw driver he sound goes away.  what did i mess up?

Click to expand...

Your soldering.

gswan said:

Your soldering.

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Also go over where wires are making a mechanical connection to the PCB (where wires connect to terminal blocks).

But, yes, most likely solder joints. 

I thought I had bought the right rotary switch for the VU meter mode but while figuring out how to wire it to gyrafs meter board I realised it needs to be 4P3T and I instead got a 2P3T. In The schematic it looks as though it's a 2P3T but gyrafs meter board has traces for a 3rd pole. I've been looking at the board and schematic trying to figure out what the extra traces are for. To me, according to the schematic it looks like you have the X Y signal coming from what I think is the output/input XLR which is regulated by the resistors to either show +4 or +8 dBu and the GR position which I think just displays nothing.
I've read that the mnats version just has this switch set to GR/bypass/Vu or something like that which I think would incorporate the GR off switch usually located on the attack pot. Can anyone clear this up for me?

trashcanman said:

I thought I had bought the right rotary switch for the VU meter mode but while figuring out how to wire it to gyrafs meter board I realised it needs to be 4P3T and I instead got a 2P3T. In The schematic it looks as though it's a 2P3T but gyrafs meter board has traces for a 3rd pole. I've been looking at the board and schematic trying to figure out what the extra traces are for. To me, according to the schematic it looks like you have the X Y signal coming from what I think is the output/input XLR which is regulated by the resistors to either show +4 or +8 dBu and the GR position which I think just displays nothing.
I've read that the mnats version just has this switch set to GR/bypass/Vu or something like that which I think would incorporate the GR off switch usually located on the attack pot. Can anyone clear this up for me?

Click to expand...

X and Y is just the output signal from pin 2 and pin 3 of the output XLR. Its the raw audio output AC, and yes it goes through a 3.6K for +4 and an 8.2K for +8.  You don't really need both, most people never you either, they just stay in GR mode.

GR/bypass/Vu is GR metering, GR OFF (usually on the attack), and +4 (or +8).

Mike

Where should the meter be when I go into 'brit' mode (all 4 in)? 

I have built 2 units, one slams all the way to the right, the other goes +2.  the one that slams won't calibrate right for the GR reduction (i only get -9db, before running out of  trimmer), the one that goes to +2 calibrate perfectly.

denov said:

Where should the meter be when I go into 'brit' mode (all 4 in)? 

I have built 2 units, one slams all the way to the right, the other goes +2.  the one that slams won't calibrate right for the GR reduction (i only get -9db, before running out of  trimmer), the one that goes to +2 calibrate perfectly.

Click to expand...

Should slam right.

i'm seeing ~14v on the collectors of Q12-13.  clues to what to look at or for?

dbonin said:

Make sure you don't have the output and release pots swapped - if they ARE swapped you will typically get through the first two calibrations but not be able to do the final meter calibration.  Ask me how I know this.  :
To check the pots AFTER they are wired up  and attached to the face plate, just set your dmm to measure resistance and put your test leads on the middle wiper and one of the outside wipers - turn the knob all the way to each extreme and note the largest resistance reading for each of the pots.  The OUTPUT pot should read close to 250 k if it is the correct pot.  NOTE!...  to test this properly, disconnect the output pot from where it is wired to the PCB (if using terminal connects) - if you are hard wired to the PCB your resistance will read LESS than 250k on the pot at the highest setting. That's normal.  If you are wired up completely and you measure 250k on the output pot you have the WRONG POT on the output.

Click to expand...

Hi there. I'm coming back to finishing my Rev D off after letting it sit for a while. It seems to work, but the release knob seems to not be working. Searching, I found this post and I tested the pots. They LOOK exactly the same. They even have the same number stamped on them (384; not sure if that number means they are the same, though....)

Anyway, I tested them and I want to make sure I did the test correctly. I did not disconnect anything. I joust checked the max resistance on each pot. The pot that is currently in the release position got a reading of 239.9k. The pot in the output position got a reading of nearly 269.6k.  If I am understanding what you wrote here, my pots are in the wrong positions. Are these readings telling you that?

Thanks!

Commander Fluffypants said:

Hi there. I'm coming back to finishing my Rev D off after letting it sit for a while. It seems to work, but the release knob seems to not be working. Searching, I found this post and I tested the pots. They LOOK exactly the same. They even have the same number stamped on them (384; not sure if that number means they are the same, though....)

Anyway, I tested them and I want to make sure I did the test correctly. I did not disconnect anything. I joust checked the max resistance on each pot. The pot that is currently in the release position got a reading of 239.9k. The pot in the output position got a reading of nearly 269.6k.  If I am understanding what you wrote here, my pots are in the wrong positions. Are these readings telling you that?

Thanks!

Click to expand...

There is a 270K R is parallel across it so that's going to slug the pot.  Check the value on your C22 cap and solder conditions. Also importantly check all your attack release wiring.

denov said:

i'm seeing ~14v on the collectors of Q12-13.  clues to what to look at or for?

Click to expand...

The voltages in the schematic are with the unit properly calibrated so you'll see messed up voltages if there is an issue anywhere in the small GR Amp circuit.  Check every component and every solder joint in the GR AMP. Check all the wiring connections to and from it.

Mike

Hairball Audio said:

There is a 270K R is parallel across it so that's going to slug the pot.  Check the value on your C22 cap and solder conditions. Also importantly check all your attack release wiring.

Click to expand...

Everything seems cool, except:

My release pot is 250K and my output pot is B5M.

Those are switched, aren't they?

Commander Fluffypants said:

Everything seems cool, except:

My release pot is 250K and my output pot is B5M.

Those are switched, aren't they?

Click to expand...

Ya that's your problem.

Hairball Audio said:

Ya that's your problem.

Click to expand...

Finding it was the hard part. Fixing it will be easy. This is what I get for buying a partially built one off of Gearlsutz...

Thanks, Mike!

Hello,

I'm very happy because my 1176 works well, there is compression and levels run ok.

There's just the needle that does not indicate the Gain Reduction  :-\ (part 3 of calibration)
Can you help me locate where the problem may lie?

Thanks,