[BUILD] 1176LN Rev D DIY

[andydiy]

The Q "Bias Adjustment settings, I can not be mobilized R59,  1176 VU no action.

The trim pot right direction in the picture?

The trim pot we Vishay 2K.

if the 5K  have better been ?

I hope you can help me!

Thank you!

 

[ln76d]

The Q "Bias Adjustment settings, I can not be mobilized R59,  1176 VU no action.

The trim pot right direction in the picture?

The trim pot we Vishay 2K.

if the 5K  have better been ?

I hope you can help me!

Thank you!

Hi andydiy!
I don't know if it matters, but on my pcb i have these three 2K trim pots (without 100R) in reversed direction, as on mnats pcb photos.
You should stay with original value, I think this is not the cause.
If you give a larger pot, decrease the range of manual adjustments in range 0-2K.
Higher resistance is unnecessary at this point - i think

 

[braeden]

DIY'ers!

Could someone please explain how to wire the rotary switch version of the 1176?

I don't understand where the shielded wire from Pad #22 of the main board is running, I am guessing it goes straight to the meter PCB? But then where does it go?
I've been following the Hairball Rev D pages and I'm just confused now.

It is my understanding that the .22uF capacitor and resistor on the attack pot/SPDT switch are no longer required as well as the resistor for the release pot as they are on the ratio PCB. Is this correct?

Do I connect the shield and ground of Pad 7 on the main board directly to the ratio PCB Pad 7?

How do I wire the attack SPDT switch and what cables go where for each lug?

I'm sorry for all the questions, I am absolutely puzzled and would not be asking otherwise.

Any help is appreciated,
Thanks!

 

[ln76d]

Did you checked this?

http://mnats.net/1176-wiring-rotary.html

This might help you also, but is hard to find picture in better resolution and with a better angle

http://img.photobucket.com/albums/v295/mnats/dual_1176_top_640.jpg

 

[braeden]

Yeah I've read all the wiring guides available,
I don't know how the SPDT attack switch is wired to the meter & ratio PCB's... as in, where is Pad 4, Pad 22 and GND connected in relation to the attack switch?

 

[ln76d]

Do you know that mnats rotary version don't include spdt on potentiometer?
Bypass is applied in meter switch.

 

[braeden]

Ahh what an idiot! Of course!

Thank you very much, problem solved

 

[ln76d]

No, youre not

There is nowhere written explicitly that the rotary version has such a solution.
At first glance, it is not so obvious.

Pad 22 and relative gnd is on main pcb.
I didn't analyse yet, how to connect external spdt switch. In my dual clone i want to apply bypass on toggle switch and in switch meter rotary section put +8 instead bypass. First what you should do if you want to use spdt switch as an bypass, don't use meter pcb, you need to wire directly to the switch.

Think good, do you really need to apply bypass on spdt. Original solution is, in my opinion, very dumb. To compare how GR affect on signal you must always turn off attack, so there's no option to compare in real-time.
I was thinking to remove bypass at all (and this is not a true bypass), because i'll be using clones only with DAW, where's better "one click" bypass option
I remained with bypass option with two reason.
Toggle switch looks good on my front panel design
Maybe i'll use bypassed audio path for line level signals to get more tranny sound

 

[braeden]

Well, I blew a resistor (R32), which is pretty common as far as I have seen. The wiring that I had for the transformer originally was correct, it was the sheer lack of confidence/hoping for everything to work the first time that I had "re-corrected" the output transformer wires only to find that I was referencing the wrong guide.

The weird thing is, after replacing R32 on the burnt out board it is now working, but the other board keeps blowing fuses. I can't see any shorts anywhere, ahh this is going to be fun.

Hopefully everything works out!

 

[number2]

Q13 is a problem: I read -1.7 VDC on the top pin. (board oriented with mnats logo in bottom left corner)

[these are  npn's so I guess that is the emitter because the typical voltage schematic reads -1.63vdc and it's the arrow pointing away?]

I get +11.11 vdc on the center pin. (is that the base?)

and on the bottom pin I get -0.9 vdc (or is this the base b/c the schematic says the base is -1.04 vdc and the collector should be +9.75 vdc?)
I'm also getting the same +11 vdc on both ends of R74 which I was told was no good.

what do I do?

Start by downloading the datasheet for the transistor and confirm the pin configuration:
http://www.centralsemi.com/PDFs/products/2n3707-3711.pdf

Seems like your voltages may be ok.  Look at the schematic with V added:
http://mnats.net/files/1176REVD_VOLTS.pdf

See R74? Voltage is simular on both sides.  In fact the EBC of Q12 and Q 13 should be similar.

Mike

OK from the data sheet it looks to me like the Emitter is the top (mnats board oriented with logo in bottom left)
the collector in the middle and the base is on bottom.

So Q13 voltages are close enough?

 

[zekester]

Just figured my issue to be as mentioned earlier in the thread, funky power transformer. It seems to be sensitive to a little movement. I read through and found a few people with issues with these, is there a high failure rate on the avel lindbergs?

 

[Echo North]

Just figured my issue to be as mentioned earlier in the thread, funky power transformer. It seems to be sensitive to a little movement. I read through and found a few people with issues with these, is there a high failure rate on the avel lindbergs?

Shouldn't be.  Maybe 3% at the most.

 

[zekester]

Just figured my issue to be as mentioned earlier in the thread, funky power transformer. It seems to be sensitive to a little movement. I read through and found a few people with issues with these, is there a high failure rate on the avel lindbergs?

Shouldn't be.  Maybe 3% at the most.

I put in an order for a new one, so that should get me back up and running again. Hopefully, I'll be in the 97% on this one 

 

[Echo North]

Just figured my issue to be as mentioned earlier in the thread, funky power transformer. It seems to be sensitive to a little movement. I read through and found a few people with issues with these, is there a high failure rate on the avel lindbergs?

Shouldn't be.  Maybe 3% at the most.

I put in an order for a new one, so that should get me back up and running again. Hopefully, I'll be in the 97% on this one 

If the new one works fine (confirming the first one you got was bad), let me know and I'll refund your second order.

 

[zekester]

Just figured my issue to be as mentioned earlier in the thread, funky power transformer. It seems to be sensitive to a little movement. I read through and found a few people with issues with these, is there a high failure rate on the avel lindbergs?

Shouldn't be.  Maybe 3% at the most.

I put in an order for a new one, so that should get me back up and running again. Hopefully, I'll be in the 97% on this one 

If the new one works fine (confirming the first one you got was bad), let me know and I'll refund your second order.

Will do. I appreciate it.

 

[TheWolfman]

So after having to take a break for a while from my project due to having to actually do some recording I have FINALLY solved my Meter issue!! ;D

Turns out that my board had a bad Pad on R75....should have checked this really,but I really didn't think it was the case.It was on the middle leg of the cermet so,I just redrew the trace with some conductive pint and soldered across it.

I have now happily managed to complete the first two steps of the calibration procedure.However when it comes to step three I cannot complete it because I can never get the Meter to drop by 10db when set into +4 mode.This is mainly due to the fact that the output control has to go so low in order for it to be at 0 whilst driving enough input to get enough Gain Reduction that it goes into the zone of  the weird self oscilation problem that's still present when the Output is almost Fully Conter-Clockwise.

This issue can be seen towards the end of the video I put together previously:

http://www.youtube.com/watch?v=ifbG5rmt56A&feature=plcp

Does anyone have ANY idea what this issue could possibly be?Because I haven't got a 'Scooby-Doo'....that means Clue for you non brits!.

I've also just noticed that the issue only happens when the Output is connected.If it's not connected it doesn't happen.

Any help as usual would be much much appreciated as I'm sooooooo close!

Thanks

 

[TheWolfman]

Sooooooooooooooooooooooooooooo........

I'm pleased to announce that I have found the fault and fixed it.I now have a beautifully calibrated unit which is ready to rock! 8)

Unbelievably the fault causing the weird Oscillation was embarrassingly enough that I had wired the output XLR Hot and Cold the wrong way around!!!!! :-[
I am so used to wiring the red which is usually hot to pin 2 that I totally overlooked that it was out of phase due to the colouring of the transformer outputs!!What-a-*********!

So hopefully now there won't be any further issues and I won't have to bother anyone on this board again.

I would like to sincerely thank everyone on here for they're contributions and for taking the time to answer some really novice questions!

I would also like to encourage anyone who may have run into any issues to be patient and double-triple check even anything you possibly think might be ridiculous and no-way causing an issue....because it probably is!All of that is part of the journey and is actually invaluable in teaching you about many aspects of audio circuits.There's been tears,theres been pain and almost bloodshed on occasion but it's all worth it for the sake of sexy FET compression you built with your own (not so sexy) hands!

I Salut you all.

 

[TheWolfman]

I thought I'd take some readings of my unit to see how it responds spectrally.Here are the results for anyone thats interested:

 

[TheWolfman]

Reading 2:

 

[TheWolfman]

Reading 3: