[BUILD] 1176LN Rev D DIY

[rokus666]

Either try a test tone with an oscilloscope or some music to see if it's working, then calibrate.

If the GR meter is pinned try adjusting the pot that zeros it to see if you get a change, if not something else is wrong. Actually now that  I look at your pic again what is the white wire going to? The center pins on the switch connect to the VU VU on the pcb. The outside pins connect to 28 and 29 on the pcb (though I forget which order, or if it even matters which order). See the pic.

Actually the white corresponds to the terminal which was damaged due soldering.

Ha! I just adjusted null adjust to zero 0 in GR...

Lets paqss some sound...

 

[rokus666]

The unit seems to be passing sound.

meter works in GR, +4, +8

But it seems I cannot hear any compression...

Trying to calibrate now...

When I play 1khz sine wave from the computer, should it be set to -20db coming from computer soundcard?

 

[Echo North]

Your unit needs to be calibrated to work properly.

There is no way to convert dBFS to dBu.  dBFS is unique to your converter's capabilities and not a standard or referenced value.  Look for 0.775VAC across pin 2 and 3 of your input XLR or -17 on your sound card should get you close.

 

[Echo North]

Sorry if I've overlooked this, but is there a explanation on how to wire the bourns input attenuator ??
http://hairballaudio.com/shop/product_info.php?cPath=27&products_id=65

I should have bought the extra pcb with it, I know. Maybe some one has the schematic of this little PCB? Or the layout, so I can figure out the wireing??

Like this:
http://www.hairballaudio.com/web_images/attenuator.jpg

 

[rokus666]

I have done some button pressing, trying to adjust Q bias.

The unit is off and it won't power on. I am not getting the power rail voltage. I have checked fuse, and it seems to be intact...

 

[rokus666]

Actually I shorted GR meter (pad 22 to ground) in order to perform Q bias adjustment.

After I removed the gator clip and tried to press GR button, and that is when the unit "died"

 

[HMPS]

Any idea where to look to get this R74 to go to 0?

I can get it to -0.016 with the resistor all the way clockwise

Checking for shorts, don't see any.  What could be leaking the extra voltage to it?

 

[Echo North]

Any idea where to look to get this R74 to go to 0?

I can get it to -0.016 with the resistor all the way clockwise

Checking for shorts, don't see any.  What could be leaking the extra voltage to it?

No Idea.

Maybe a wrongly placed component or maybe not.  If everything around it looks fine you could increase the value of the trimmer to 5K or be happy with 0.016VDC which is basically 0.

 

[radiance]

Sorry if I've overlooked this, but is there a explanation on how to wire the bourns input attenuator ??
http://hairballaudio.com/shop/product_info.php?cPath=27&products_id=65

I should have bought the extra pcb with it, I know. Maybe some one has the schematic of this little PCB? Or the layout, so I can figure out the wireing??

Like this:
http://www.hairballaudio.com/web_images/attenuator.jpg

YES!
Thanks a bunch...

 

[HMPS]

Checking voltages with schematic,

Notice that Q13 is reversed on the schematic, should it be flipped around?

Voltage readings so Far

R87 29.88
CR6 -8.46(is this too low?)
R49 16.04
Q9(top to bottom) 16.62, 3.31, 2.8
R40 14.7
Q7 14.95, 4.43, 3.89

Q13 12, low almost 0, .6
Q12 12, 0, -.36
Q11 13.09

 

[rokus666]

Yep, I blew up the fuse.

This is what I've done since powered the unit for the first time:

Pressed GR button and meter was all the way up. I have adjusted NULL trim to bring down the meter to 0 VU

I have then started step 1 of calibration process. I have shorted GR meter by hooking PAD22 to ground. GR was shorted and I played 1khz tone into the unit while bringing input up to +1 db.


When I adjusted Q bias pot, counter clock wise moved the meter down, and clock wise increased the meter value.

BTW, the calibration procedure says that you should bring the q-bias pot all the way counter-clock wise. I did so, but then I couldn't trim down the signal from +1 db to 0 db

So the fuse blew when I removed the gator clip from pad22 and ground and pressed GR button...

More testing to come

 

[HMPS]

Voltage Measurements

R87 29.88
CR6 -8.46

Q10 16.04,16.62
Q9 16.62,3.39,2.83
Q8 14.32,14.95
Q7 14.95,4.43,3.89
*Q13 12, low around 0, .6*
*Q12 13.09, 0, -.36*
Q11 13.09
Q6 27.4, 2.06
Q5 24.5,3.17.2.6
Q4 3.76,.99,.43
Q14 11.26
Q3 11,1.15
Q2 1.75,1.05,.55

signal line out 29.9

how do these voltages look?

 

[andydiy]

Hi!

1. conductor shielded wire used for pin 6 as shown. you using to how much the MM wire.

2. The IEC Electrical connect wire will, to use how many mm wire?

Thx!

 

[HMPS]

I can't get it below 0.162 DCV. 

The resistor R75 is turned fully CW.

Is my reading of -8.48 on CR6 acceptable or should I fix that first?  I noticed the negative voltage dropped a little when I grounded the negative pin of C23 to chassis.

Thanks in advance

 

[Echo North]

I can't get it below 0.162 DCV. 

The resistor R75 is turned fully CW.

Is my reading of -8.48 on CR6 acceptable or should I fix that first?  I noticed the negative voltage dropped a little when I grounded the negative pin of C23 to chassis.

Thanks in advance

Yes that is too low.  You should sort that out.

 

[HMPS]

Measurements

Negative lead of CR26 -18.69
Negative lead of CR24 -8.34

Those seem off?

Where can I find the datasheet to test the transformer leads?
Avel Lindberg 2X25 30VA dual primary/secondary toroidal power transformer is what came with my Hairball kit.

Thanks!

 

[HMPS]

I'm showing similar numbers as you, how did you resolve this?

Hook up a signal to the input, use the signal tracer to see if the signal is present at the input to the pcb (output of the transformer). 
If it is, use the signal tracer to see if the signal is present at the input to the output volume pot.
If it is, then the problem is in the output amp.
Check the voltages on the components in the output amp. Check that the components are right. Post more info if you need help. Pictures of your build. Post the schematic with your voltages (listing all the voltages in text may be easier for YOU, but not for the person you are asking to help you).

checking voltages: Q13 seemed off.

Don't worry about the meter driver yet - get the signal preamp and output amp working first.

thanks so much dmp!
i signal traced and i have signal passing at all of the pots, input/output XLR's, output transfrmr and at input to pcb.

voltages:
signal preamp:
Q2: 1.05, 1.7 and 0.5
Q3: 1.75, 11.76 and 1.15  (11.76 should be closer to 12.5?)
Q14: 11.76, 29.6, 11.17

signal line amp: (is this the output amp?)
Q4: 0.98, 3.9 , 0.42
Q5: 3.2, 24.3, 2.6
Q6: 27.1, 2, 2      (this 27.1 should be closer to 28.9?)

GR control amp:
Q7: 14.82, 4.37, 3.8
Q9: 16.3, 3.38, 2.8

 

[Echo North]

They are all fine.  Any 2 conductor wire with shield that's smallish and flexible will be ok.

 

[andydiy]

Hi!

Ask you to give my opinion?

The following three types of wire to use in 1176 that the best?

(Canare L2B2AT / Sommer SC-SCUBA 14 HIGHFLEX / Belden 8451)

 

[andydiy]

Hi!

1176 Meter Circuit Board & Ratio Circuit Board.

Molex .100 K.K. Connectors.

Manufacturer Part Number can give me it?

Thx !