[BUILD] 1176LN Rev D DIY

[germoju]

hi,

sorry I'm LOST !
I made an other PCBoard and result is the same. Sound is OK, but no compression. I dont know what you do that I dont. I dont know where to search...

I changed the Attack pot and his wires... NO CHANGE.
The calibration is Ok for the step 1 and 2. but step 3, when you open compression, I dont loose any dB...

I dont know what to do now !!! Please someone has an idea ??

Some news pictures : http://flic.kr/s/aHsjyjg8WT

I filmed the calibration problem...=> http://youtu.be/UyxpICYOmNQ

Am I right ??

 

[Edward]

hi,

sorry I'm LOST !
I made an other PCBoard and result is the same. Sound is OK, but no compression. I dont know what you do that I dont. I dont know where to search...

I changed the Attack pot and his wires... NO CHANGE.
The calibration is Ok for the step 1 and 2. but step 3, when you open compression, I dont loose any dB...

I dont know what to do now !!! Please someone has an idea ??

Some news pictures : http://flic.kr/s/aHsjyjg8WT

I filmed the calibration problem...=> http://youtu.be/UyxpICYOmNQ

Am I right ??

I don't know if it matters but i left R44 in circuit when the doing calibration step one. In other words leave the jumper in while doing step one.


/E

 

[germoju]

I don't know if it matters but i left R44 in circuit when the doing calibration step one. In other word leave the jumper in while doing step one.

thanks... I did it.... but that the same....

 

[sr1200]

yeah, step 1 should have the jumper IN, also... did i see you zeroing the meter with the front panel adjustment? 44 is for the tracking adjust, and 71 is for the 0 adjust (right?)

I know it would be really late your time, but if you can skype later on tonight maybe we can look at this together... i had the SAME issue with my second unit.  I would need to see some close up pics of certain areas of the board though.

 

[Echo North]

He re-built a new board and has the sames issue, which would lead me to believe it's an off the board issue.  I'm thinking the ratio board or attack/release pot or associated wiring.

Having the jumper in/out should not effect the Q calibration I would not think.

When you switch between ratio's in GR mode does your meter jump a little?  It should.

 

[germoju]

Third...

If you put the new PCB in the same box it would indicate.

1. Something wrong with the wiring
2. Something wrong with an off the PCB part (Attack/Release Pot or Ratio PCB).  Examine the ratio PCB for shorts or cut traces.
3. You're not measuring the GR (lack of) properly.

Hope this helps!

Thanks AGAIN !!!
I dont understand => "Examine the ratio PCB for shorts or cut traces"
nd I dont understand => "You're not measuring the GR (lack of) properly"
what that's mean please ?

 

[Echo North]

Put your AC meter on the output XLR (pin 2 and 3).  Feed a large signal into the input and increase the input in GR mode.  See if the voltage drops.  That would show your GR is working and it's a meter calibration issue.

If it does not drop, I would suspect the things in my previous post.

 

[Echo North]

Check the ratio PCB, the one on the ratio push switches, for any damage.

To test if the GR is working (and just not showing on the meter) see my post above this one.

 

[Echo North]

Also, using your meter, test to make sure that GRN on the ratio PCB has continuity to pad 22 on the main board and NO continuity to BLK (ground) when in GR mode.

 

[dbonin]

in a recent 1176 rev d BOM shipment I recieved 2 100v .22uF 10% film caps - they go in C9 and C22, both in the preamp section.
The WIMA cap is polyester film .47 cents for one
the Kemet film is $2.11 for one

Is there a best place for one or the other?  would WIMA caps work in both?  I assume there is a special place for the expensive Kemet?

Thanks!
-Don

 

[pittsburgh]

I'm having an issue with test voltages, and a question on output voltages from the secondary from the transformer.

I'm getting +10, when I should be reading -10 @ CR6, and I'm reading -30 @ R87. Why would these two voltages be inverted?

More suspicious is the output marked red on the secondary of the transformer reads 6VAC, while my yellow output is reading 30VAC. Is this right?

 

[Echo North]

Do you have your meter "common" lead on the ground or center tap and the other lead on the test point? 

 

[ILOVE1176]

in a recent 1176 rev d BOM shipment I recieved 2 100v .22uF 10% film caps - they go in C9 and C22, both in the preamp section.
The WIMA cap is polyester film .47 cents for one
the Kemet film is $2.11 for one

Is there a best place for one or the other?  would WIMA caps work in both?  I assume there is a special place for the expensive Kemet?

Thanks!
-Don

Hi Don, I believe I recieved the same BOM order as you. My senses led me to believe that its simply the same part made in a different country and that it would not matter where which one was place.... I inserted the larger white part at C9. (It confused me too)

If I am in-correct please correct me guys.

Hope this helps.

Kind Regards

 

[germoju]

When you switch between ratio's in GR mode does your meter jump a little?  It should.

yes ... take a look at 6:20 => http://youtu.be/UyxpICYOmNQ

 

[Echo North]

Yes that's normal.

Did you check your AC output voltages with compression on and a test signal to see if it's reducing?

 

[germoju]

Also, have you looked at the MNAT schematic with typical voltages added?

http://mnats.net/files/1176REVD_VOLTS.pdf

Check your GR Amp section.

yes I did.

_IGP5004 par volcanovap, sur Flickr

Q1 =  G -0,39v  - S 0v      - D 0v
Q2 =  1 0,55v  - 2 1,79v  - 3 0,88v
Q3 =  1 1,17v  - 2 11,5v  - 3 1,79v
Q4 =  1 0,43v  - 2 4,03v  - 3 0,98v
Q5 =  1 2,74v  - 2 24,6v  - 3 3,0v
Q6 =  1 2,18v  - 2 2,76v  - 3 27,4v
Q7 =  1 3,95v  - 2 14,72v - 3 4,22v
Q8 =  1 14.25v - 2 29.9v  - 3 14.72v
Q9 =  1 2,89v  - 2 16,44v - 3 3,42v
Q10 = 1 16,42v - 2 29,9v  - 3 16,46v
Q11 = G -0,26v  - S -0,57v - D 8,29v
Q12 = 1 -1,2v    - 2 6,28v  - 3 -0,57v
Q13 = 1 -1,33v  - 2 6,28v  - 3 -0,73v
Q14 = 1 11,05v  - 2 29,9v  - 3 11,51v

R87 = 29,9v
CR6 = -9,7v

Can you see something wrong ? 

Q1 or/and Q11 maybe ??

 

[germoju]

Yes that's normal.

Did you check your AC output voltages with compression on and a test signal to see if it's reducing?

arfffff... I dont know how to do that...  :-[

 

[Echo North]

Basically do the meter tracking adjustment without adjusting the meter.

Do this ignoring the VU meter on the front.

Input = "24" mid rotation
Output = "24" mid rotation
Attack = full CW
Release = full CW
Compression ratio = 20:1
Meter mode = "GR"

1. Apply a signal (1 KHz, 0db).
2. Set output control for 0db as read on an external meter measuring AC volts across output XLR pin 2 and 3
3. Set attack full CCW (off position).  Set input control for +10db as read on an external
meter measuring AC volts across output XLR pin 2 and 3
4. Turn the attack control OFF (CCW) and readjust the output level control for "0" if
necessary.
5.  Repeat 7 & 8 until the output drops 10dB (2.44V to 0.775V) whenever the attack control is turned ON.

If you can do this, your unit is compressing and there is something wrong with the meter control section.

 

[acoustix]

It's really weird that the same problem is repeated a PCB to another
...

 

[Echo North]

Totally.

Also confirm that your signal generator is actually feeding your input XLR 0dB.  Put your AC meter on it and confirm you see .775V.  The 1176 has a low input impedance and if you're using a DAW or something as a signal source, I wouldn't trust any reading.  Adjust the signal so you're getting .775 on the input (pin 2 and 3).

DMM are not really designed to handle 1KhZ signals but if you have a decent one (over $20) it should read it fine.