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

[Rob Flinn]

Ciao
My rev A is ready but i Have some problems...
the meter ( hairball) work on +4 and +8 but not in GR mode  I have checked all resistor and are OK
some problems with 20:1 ratio and nuke mode...
all the trimpots don't do nothing...
some ideas?
Thanks and sorry for my english...

What I would do is check the wiring between the switches & the mains board.  If you used push switches, the diagram for interwiring wasn't very easy to understand.  If you use it in conjucntion with the circuit diagram you should be able to work out any mistakes.

With regards to the meter not working there are a number of factors.  Did you match the 2 transistors that drive the meter to within 10%? Did you match the fets ?  Other than that there are some details further back on this thread about swapping out some of the 2k trimmer to 5k ones to give you more range.  Also if you have any of the trimpots related to the meter at extreme settings then you may be out of range to get it working, since they all react with each other.

 

[ilfungo]

Thanks Rob
Q1-Q11 (2N4457) Are selected from hairball...
Q7-Q10    Q12-Q13 (2N3707) are match hfe (228) ...
the value 250 is an absolute value?
In GR the meter is on the left -20 and do nothing
I 've used 5k trimpot for R44
and 2k for the other...
Thanks

 

[Rob Flinn]

Check that the trimpots have continuity to the other components they're connected,  Also check you wiring between the boards against a circuit diagram to make sure you have it all hooked up properly.  The hook up diagram that is posted here is easy to misinterpret !

 

[ilfungo]

sorry Rob
but I ama a beginner...
I have connnected together TP10 and TP11 and in GR mode the meter go to 0 but it work in positive ???
the trimpot now work....
do you have some idea?
Thanks

TP10 and TP11 must be connected together?
How many links I must do?
Thanks

 

[Rob Flinn]

No test point 10 & 11 should NOT be connected together.  with no input signal you connect a volt meter across 10 & 11, on a 2v dc range, & use the null trimmer to get the vu meter to read zero.  This is AFTER you have set the Q bias trimmer, which is another procedure.   

Once you have it at zero you reset the meter zero trimmer so that the meter points to zero.  This will cause your  volt meter to move from zero so you retrim that, which will cause the vu meter to move a way from zero. so you repeat the cycle until both meters are at zero.

When this is done you connect the jumper near R44.  you now apply a large signal to the input & look at the output. Set the output quite high.  adjust the input control so that on an external meter you see a drop of -10dB when you switch between bypass & compression mode.
Whe this happens you adjut the meter tracking adjust pot so that the VU meter -10db.  bypass the compressor.  reset the the VU to zero. switch into compression mode, & readjust the tracking to show -10dB, repeat this so until in bypass the VU sits at zero & in comp mode it shows -10dB.

You need the unit to have warmed up for 1/2 to 1 hour before you do any of this !!

This is all quite well documented elsewhere, & somewhere ther are some your films to show you how this is done.

sorry Rob
but I ama a beginner...
I have connnected together TP10 and TP11 and in GR mode the meter go to 0 but it work in positive ???
the trimpot now work....
do you have some idea?
Thanks

TP10 and TP11 must be connected together?
How many links I must do?
Thanks

 

[danjpiscina]

has anyone had the opportunity to A/B this to an original blue stripe? it would be awesome if someone could post some examples. i know that the re-issue http://www.uaudio.com/products/hardware/1176ae/index.html sounds different and i think it has a lot to do with the fact that they incorporated the LN circuitry (it is based on a blue stripe and a blackface, to get the "best of both worlds" but i don't want that).

DP.

 

[ilfungo]

Ciao Rob
tanks so much for your help....
My rev A it's Ok and have a great sound!!!
in  nuke mode I have noticed that there are problems when the input level  is low...
Do you have the same problem?
which is it the resistance that I must use for connecting the  12V lamp of the meter to the main board?
Thanks

 

[Stagefright13]

To figure out the resistance check here:

http://www.groupdiy.com/index.php?topic=275.0

 

[Rob Flinn]

Ilfungo

I suggest that you change the 3 resistors detailed in this thread. 

http://www.groupdiy.com/index.php?topic=34502.0

R46 & the 2 ratio board resistors.  It makes the compressor much easier to operate & more stable in nuke mode.

 

[cannikin]

Hey Rob or anyone.

Would there be any negative effects if I were to use 10uf caps in place of the 6.8uf caps?  most circuits can handle a little extra capacitance but the 1176 is a touchy circuit and I have yet to successfully build one of these correctly (hopefully this will be the first), so I figured I'd ask.  thanks

 

[Rob Flinn]

Hey Rob or anyone.

Would there be any negative effects if I were to use 10uf caps in place of the 6.8uf caps?   most circuits can handle a little extra capacitance but the 1176 is a touchy circuit and I have yet to successfully build one of these correctly (hopefully this will be the first), so I figured I'd ask.   thanks

I don't know, sorry.  Maybe you could try it.

 

[RedNoise]

Hi ,
could someone check if I'm correct with the jumpers drawn on the picture below??

I've read Mnats psu pdf , but I'm not sure.
Thanks.

 

[ilfungo]

Ciao
How it is possible to make a  stereo version  of blue stripe?
Thanks...

 

[mnats]

How it is possible to make a  stereo version  of blue stripe?

Exactly the same as any other version of the 1176. The primary difference between the blue stripe and other revisions is in the audio path, not the method by which compression is achieved.

 

[ilfungo]

ciao mnats
which is the pad to connect for the stereo?
Thanks

 

[RedNoise]

Hi ,
could someone check if I'm correct with the jumpers drawn on the picture below??

I've read Mnats psu pdf , but I'm not sure.
Thanks.

bump

 

[spica]

Ilfungo, connect Pad 7 to stereo link two units.  The 2N5457 should be matched between both units.  Read through the Rev. D page, there is some discussion of it there.

RedNoise, look at the bottom of the PCB to see the traces.  I believe you want to move both wires over one pad to the right in the picture.

-Tony

 

[cannikin]

Mako & Ed

any further insights to the 1108 Pre.  I would definitely get a couple of those if you were to make pcb with just the 1108 pre.

 

[ilfungo]

Ciao
I just finished my blue stripe, but I have a problem ...
R32 (39ohm) burns just turn on the compressor
you have any idea?


Thanks

 

[Rob Flinn]

check it's value & that of the surrounding resistors in that part of the circuit for starters.