[BUILD] 1176 Rev A - Back to the beginning...

[acoustix]

ok guys
I hoped never to post here, but .... I have a problem with my Reva  :-\.

For now I have not started the calibration procedure, but I prefer to explain my problem before going further.

So independantly to the others paramters :

In GR mode, O the VU ok and when i turn ouptut pot fully CW, i see 20dB drop to the VU.
In +4 or +8, when i turn ouptut pot fully CW, the VU is going fully to the right (more far as +3dB) 

If i put a dynamic directly into the input, mid position to the input and output pot, i can see the signal pass and the reduction in GR mode.

Anybody have an idea ?

I have lot of gig in january, i have to say i'm in the poo !!!  ;D

 

[atticmike]

ok guys
I hoped never to post here, but .... I have a problem with my Reva  :-\.

For now I have not started the calibration procedure, but I prefer to explain my problem before going further.

So independantly to the others paramters :

In GR mode, O the VU ok and when i turn ouptut pot fully CW, i see 20dB drop to the VU.
In +4 or +8, when i turn ouptut pot fully CW, the VU is going fully to the right (more far as +3dB) 

If i put a dynamic directly into the input, mid position to the input and output pot, i can see the signal pass and the reduction in GR mode.

Anybody have an idea ?

I have lot of gig in january, i have to say i'm in the poo !!!  ;D

That's what the calibration is for

No wonder why all the metering is off

 

[ilfungo]

ok guys
I hoped never to post here, but .... I have a problem with my Reva  :-\.

For now I have not started the calibration procedure, but I prefer to explain my problem before going further.

So independantly to the others paramters :

In GR mode, O the VU ok and when i turn ouptut pot fully CW, i see 20dB drop to the VU.
In +4 or +8, when i turn ouptut pot fully CW, the VU is going fully to the right (more far as +3dB) 

If i put a dynamic directly into the input, mid position to the input and output pot, i can see the signal pass and the reduction in GR mode.

Anybody have an idea ?

I have lot of gig in january, i have to say i'm in the poo !!!  ;D

I would not be wrong, I'm not an expert but it could be a wiring problem
are you sure of your connections?

 

[atticmike]

Actually, I find the 10 db calibration on the output kind of extreme.

What is mnat's & mark's statement to this art of adjustment?

I mean, with 2.7 V, you get literally beyond 10 db output.

 

[acoustix]

Just for information
2N3707 for Q12 et Q13 (match hfe)
2N5808 with alternate pad for the rest
2N5457 from hairball
J309 BUT when part arrived it's J309_D26Z (???)

My +30 and -10 are fine.

Who has a schematic with reference voltage (as the mnats/jakob revJ) for me please ?

I would not be wrong, I'm not an expert but it could be a wiring problem
are you sure of your connections?

Checked and double checked, i post somes HD picts here  :'( :-\

That's what the calibration is for

No wonder why all the metering is off

 

[acoustix]

Ok so ... truth is out there ;D

Comp Off, input CCW, output CW
If i put a clips and JUST ONE (the other end is nowhere) to GND pad 16 the comp is ok 
When i remove it, the meter jump and clip (i can hear it) to the right.

EDIT :

So ... if i put a finger on the 2 caps C1, C2, the meter clips.
I changed C2 (orange drop) and i replaced it with a wimp and problem partially solve  ???

 

[atticmike]

My stereo unit is finished so far, apart from my badly done case cover which has to be re-milled at couple of spots (Missed out the fact that the holes of the upper case were not synchronous, bummer).

However, there is one thing I have to get off my chest which concerns the VU calibration.

Step 3, where you adjust the output level and create a compression of 10 db is not as flawless / easily convertible as stated on mnat's tutorial, especially if you feed it with the original calibration method (2.4 & 2.7 = 10 DB meterless calibration approach). By the first time you adjust the VU to 10 dB (2.45 V) and accordingly tweak the tracking adjustment pot, there will be an offset of -1 db at zero vu (GR OFF). What I did was basically calibrate it to the previous mentioned standard approach (including the tracking adjustment) and then continued by recalibrating it to 2.75 with still 0.775 as the reference GR level. After that, I did not compensate for the meter offset by turning the tracking adjustment pot but rather by tweaking R71 at the front panel and the successive R75 zero volts procedure (allowing me to calibrate back to 2.45 = 10 dB and still being able to capture an almost zero adjustment readout, for both 0 and -10).

At long last, a speck of offset was still appearing which I got rid off with a similar approach. Again, after having re-calibrated the measurement to 2.45 V instead of 2.75 V, which I just used to get off the -1 db offset, I turned the front panel R71 pot and doubled the missing from -0.5 db to +0.5, which was then equally 1 db missing for -10. After another zero volts adjustment for R75, I compensated for the missing gap on both 0 and -10 (GR & OFF Mode).

The only downside of this kind of approach is with the outcome of VU Mode +8, which is +7 for me now That's what I truly call DIY!

All things considered I am more than happy to have built this clone, beating out my friend's original 1176 LN

 

[AdoreaRecordingStudio]

So this is my first post and i've looked pretty hard but this is the closest and most relevant place I can think to post this problem with my Hairball Audio 1176 rev A. EVERYTHING WORKS- by everything i mean, everything except my meter isn't metering- oops.. I'm getting 29v at the power supply, audio is passing in and out, all ratio switches work, attack + release, and INPUT & OUTPUT work great. Where is the most likey place I dropped the ball here? Ive spent all day (literally) with a probe trying to find the cold solder joint or crossed wire and i'm stumped. Help please? aka be gentle lol ?

Travis

 

[Lucin Niega]

I had the compressor working with the tx from hairball. I had the secondary wired with the orange and black tied together. It was working. I also noticed that it seemed to work with orange and red tied together. I was trying to get through the meter calibration and got stuck on the 3rd calibration. I recently came back to it to try my hand at the calibration again. The unit doesn't work now. I'm sending a 1k @ .775v to the input but the output is very low and very noisy. I changed the fuse, which seemed to take the noise away but the output is still very low.

I have the secondary wired orange and red which seems to be the correct way. Is this right? Also, if I jiggle the cables coming from the meter it makes the needle move back and forth. Any ideas on why the output could be so low?

 

[Lucin Niega]

Update: With nothing plugged into the input, the output is 3.5v . Going to check the output v-resistor wiring.

 

[atticmike]

Update: With nothing plugged into the input, the output is 3.5v . Going to check the output v-resistor wiring.

Be sure to have checked every little corner of your build. The worst mistakes are usually the ones you easily oversee or take for granted. Also, look for the output transformer's wiring on the schematic in case you've used someone else's picture wiring reference.

Worst case scenario would be a faulty / malfunctioning output transformer which to be honest has never come to my attention. Ed's doing a good job in recreating these issues.

Mike

 

[Lucin Niega]

Hey Mike,

You're in the States, right? How do you have your secondary wired? Orange and red tied together? Or is it different?

 

[Lucin Niega]

Do all the voltages agree with the schematic posted on my site?
[/quote]

I've looked at 2 schematics on your site but I didn't see one that references voltages? Can someone help me out with this.

Also, I'm not getting anything on the output of the input transformer. Feeding it a 1k tone nothing is coming out. How to test it?

 

[Lucin Niega]

Alright, I narrowed the problem down to the input transformer. The signal (1k .775v) gets to the input of the input transformer but I get nothing out of the output (of the input transformer). I checked conductivity from the output to the terminals, ok there. I checked the solder on the tx board and went over it with the iron to make sure the connections were good, ok there. Ground to the chassis is good.

I'm going to order another input tx and see how it goes.

 

[acoustix]

I had the compressor working with the tx from hairball. I had the secondary wired with the orange and black tied together. It was working. I also noticed that it seemed to work with orange and red tied together. I was trying to get through the meter calibration and got stuck on the 3rd calibration. I recently came back to it to try my hand at the calibration again. The unit doesn't work now. I'm sending a 1k @ .775v to the input but the output is very low and very noisy. I changed the fuse, which seemed to take the noise away but the output is still very low.

I have the secondary wired orange and red which seems to be the correct way. Is this right? Also, if I jiggle the cables coming from the meter it makes the needle move back and forth. Any ideas on why the output could be so low?

From Mnats wiring guide :

NOTE: If you are using an original or Hairball 5002 reproduction, you must also tie the yellow and orange output wires together to connect the secondary windings in series.

 

[Lucin Niega]

So many transformers, lol. I was talking about the power tx there. I should've clarified. I have yellow and orange tied together on the output tx.

 

[Volume11]

In regards to your meter not working, make sure that it is not tightened too tight to the chasis. I made this mistake, and my meter would stick. Hopefully it's that simple. I've had mine now for over two months, and I still can't get the q bias adjustment to do anything 

 

[Lucin Niega]

Okay, I replaced my input transformer and it sounds a little better (louder). I'm getting audio to pass through the unit but it sounds like it has a high pass filter on the output. The meter is also pegged when switched to GR. It barley moves when set to +4 or +8. It used to work but suddenly stopped.

Is there a particular resistor that could have blown that I should be checking or something? Any help will be appreciated.

Thanks

 

[Lucin Niega]

I think the problem is in the line amp. I'm going to test Q4, Q5, Q6. I can hear the compression working but the output is not hot enough. I will report back.

 

[Lucin Niega]

I just checked Q5 and Q6. They tested fine. I feel like I'm barking up the wrong tree here. Any ideas?