[BUILD] 1176LN Rev D DIY

[jefepeters]

20 or 25, I can't remember. The click is the end.

It should go down to 0 VDC, that is your issue. Until you can get it below -1 VDC you are not going to see much compression.  CR2/CR3 in the right orientation?  What are you Pad 21 voltages per the guide?

Mike

Yes, CR2/CR3 are correct.

For test point 21, the voltages are all lower than the specified values:


20:1  -6.22 VDC
12:1  -2.74 VDC
8:1  -1.43 VDC
4:1  -0.35 VDC

 

[francesco vitaliti]

Hi Mike

Check the value of R58, R61, R62, R63, R64.

Mike

After checking, pulling away and soldering back lots of resistors, diodes, and caps, my 1176 is behaving better.
In the meanwhile i'm getting a lot more knowledge and curiosity in electronics, thank you for that!

I changed the 2k q-bias trimmer with a new one, and soldered back some "faulty/not perfect" connections.
Now what i have is -1.18 DCV- 0.00 DCV at TP18 (lower than expected).
Now that i have the opposite issue, what you suggest?

Thanks again for your help

 

[Echo North]

Hi Mike

After checking, pulling away and soldering back lots of resistors, diodes, and caps, my 1176 is behaving better.
In the meanwhile i'm getting a lot more knowledge and curiosity in electronics, thank you for that!

I changed the 2k q-bias trimmer with a new one, and soldered back some "faulty/not perfect" connections.
Now what i have is -1.18 DCV- 0.00 DCV at TP18 (lower than expected).
Now that i have the opposite issue, what you suggest?

Thanks again for your help

Hmmmmm make sure your R35/R60 are soldered well and the correct value.

What is your V DC on either side of R35?

 

[Echo North]

Yes, CR2/CR3 are correct.

For test point 21, the voltages are all lower than the specified values:


20:1  -6.22 VDC
12:1  -2.74 VDC
8:1  -1.43 VDC
4:1  -0.35 VDC

Check R58 and R61 to 63.

Are those right?

 

[jefepeters]

Check R58 and R61 to 63.

Are those right?

Here's what I get:


R1 (R58) = 146Ω (150Ω)
R2 (R61) = 434Ω (470Ω)
R3 (R62) = 509Ω (560Ω)
R4 (R63) = 1.1KΩ (1.5KΩ)

 

[Echo North]

Here's what I get:


R1 (R58) = 146Ω (150Ω)
R2 (R61) = 434Ω (470Ω)
R3 (R62) = 509Ω (560Ω)
R4 (R63) = 1.1KΩ (1.5KΩ)

I assume that's with them still in circuit?

Does one of the outside legs on your bias trimmer have continuity to ground?

Mike

 

[jefepeters]

I assume that's with them still in circuit?

Does one of the outside legs on your bias trimmer have continuity to ground?

Mike

Yes to both questions. (Outside leg closest to edge of pcb).

Thanks,
Justin

 

[Echo North]

Yes to both questions. (Outside leg closest to edge of pcb).

Thanks,
Justin

And you can't get PAD 18 down to 0 VDC?

 

[jefepeters]

And you can't get PAD 18 down to 0 VDC?

Correct, the lowest I can get it is -1.11 VDC. I assume there is no point in turning it beyond the click.

 

[Echo North]

Correct, the lowest I can get it is -1.11 VDC. I assume there is no point in turning it beyond the click.

Weird.  What are you using for your common/ground probe test point? Screw hole in the enclosure?

 

[jefepeters]

Weird.  What are you using for your common/ground probe test point? Screw hole in the enclosure?

The IEC ground.

 

[Echo North]

Is there continuity between that and the ground plane on the PCB?

 

[jefepeters]

Is there continuity between that and the ground plane on the PCB?

Meaning the green wire soldered to the negative lead of C25? Yes.

 

[Echo North]

Meaning the green wire soldered to the negative lead of C25? Yes.

Can you get the continuity between the ground lead on your bias trimmer and the middle lead down to 0Ω by turning it to that side all the way?

 

[jefepeters]

Can you get the continuity between the ground lead on your bias trimmer and the middle lead down to 0Ω by turning it to that side all the way?

Yes. Fully CCW it is 0.3Ω.

 

[Echo North]

Yes. Fully CCW it is 0.3Ω.

Just doesn't add up. Pad 18 is on the middle lead of that bias trimmer. If that is grounded, pad 18 should be 0VDC.  Does pad 18 have continuity to that middle pin? Trimmer position doesn't matter.

 

[jefepeters]

Just doesn't add up. Pad 18 is on the middle lead of that bias trimmer. If that is grounded, pad 18 should be 0VDC.  Does pad 18 have continuity to that middle pin? Trimmer position doesn't matter.

I tried doing step two in the troubleshooting guide, and I'm not measuring any voltage at TP1.  When I apply .775 VAC as measured on the XLR cable,  I get 0.157 VAC on the XLR input jack, 0.081 VAC on the transformer input PCB and 0 VAC on the transformer output PCB (both when grounded to the case and the negative output on the PCB).

 

[francesco vitaliti]

Hmmmmm make sure your R35/R60 are soldered well and the correct value.

What is your V DC on either side of R35?

I went trough all the calibration steps and the compressor is finally compressing  ;D
Today my input dc at r59 is -1.87 (two days ago was -1,18)
r35 is -9.65 , -1.87.
r 60 is in great shape and giving me -1,87, 0.00 DCV

Should i care about that or should i just close the case and record and mix a lot of music through it?

 

[Echo North]

I tried doing step two in the troubleshooting guide, and I'm not measuring any voltage at TP1.  When I apply .775 VAC as measured on the XLR cable,  I get 0.157 VAC on the XLR input jack, 0.081 VAC on the transformer input PCB and 0 VAC on the transformer output PCB (both when grounded to the case and the negative output on the PCB).

That's a different issue.

Can you increase your signal so you see about 0.775 VAC between pin 2 and 3 of the input XLR?

Mike

 

[Echo North]

I went trough all the calibration steps and the compressor is finally compressing  ;D
Today my input dc at r59 is -1.87 (two days ago was -1,18)
r35 is -9.65 , -1.87.
r 60 is in great shape and giving me -1,87, 0.00 DCV

Should i care about that or should i just close the case and record and mix a lot of music through it?

If it is calibrated you're all set.

Mike