[BUILD] 1176 Rev F/G - new board, new transformer!

[alchemystudio]

i speak 100% French, 50% Italian, 15% English, and 0,003% German..  ;D

 

[late]

Finished my rev F. Everything works fine but meter tracking not pass. Can't get 10db drop when switch attack on. My meter not drop at all.


Ah it need way more input, have ic input. Is it normal that ic input need way more input after it starts compressing? My A and D revisions with transformer need about 40% less for same result.

 

[Walshy]

Hi,

Building my first 1176 Rev F and all is good so far. Just a quick question. I'm stuffing the capacitors and seem to be one short. In my Mouser cart (link from Hairball site) I was supplied 1 x Film Capacitors 63V 1uF 5%. I believe I need 2 for positions C1 and C9. The mnats BOM shows that I need 2 x 1.0uF CAPACITOR, FILM OR ELECTROLYTIC. The schematic shows I need 2 as well. I assume my Mouser cart was incomplete. Could someone please confirm this?

Oh almost forgot. According to the schematic and the overlay, I need polarized 1uF caps for positions C1 and C9. Any help would be great!

Thanks a lot!

Walshy

 

[Echo North]

Hi,

Building my first 1176 Rev F and all is good so far. Just a quick question. I'm stuffing the capacitors and seem to be one short. In my Mouser cart (link from Hairball site) I was supplied 1 x Film Capacitors 63V 1uF 5%. I believe I need 2 for positions C1 and C9. The mnats BOM shows that I need 2 x 1.0uF CAPACITOR, FILM OR ELECTROLYTIC. The schematic shows I need 2 as well. I assume my Mouser cart was incomplete. Could someone please confirm this?

Oh almost forgot. According to the schematic and the overlay, I need polarized 1uF caps for positions C1 and C9. Any help would be great!

Thanks a lot!

Walshy

The MNATS BOM is considered most accurate.  The mouser cart is off let me know and I can fix it.

 

[mnats]

The MNATS BOM is considered most accurate. 

Actually the schematic itself is probably the most accurate if you use the correct version(s) for the various sections. So feel free to compile one yourself.

 

[Walshy]

Hi all,

Finished my Rev F this week. What a rewarding experience! It worked perfectly first time. There's a few points I'd like to share which I think will help other beginner DIYers who may decide to give this project a go.

1. The Mouser cart link on the Hairball site is slightly incorrect. You'll need 2 x 1uf film caps, not one. Secondly, there's no need for the 512-1N4148 Fairchild Regulator that's included in the cart. You'll need 2 x 534-7316 locking lug terminals for ground connections. Lastly, it might be worth getting 2 x 4.8mm female blade terminals and 2 x 3mm female blade terminals in order to correctly attach wires to the VU meter. I sourced the blade terminals from Maplin here in London although the quality isn't the best. Lastly, mnats uses Molex connectors on his meter board and ratio board. I didn't have any so I soldered the wires onto the board directly. Choice is yours.

2. Earlier is this thread there was some discussion on wiring the attack pot CW lug to the pcb. In the wiring guide it says to solder the shield to ground next to pad 7. On the Rev F board there is no ground pad next to pad 7. I opted to wire the shield to the ground pad next to the input pad just along from pad 7. Dunno if this is necessary. I struggled to interpret this part of the schematic and I noted this connection just in case there was any audible hum when I tested the unit for the first time. There wasn't so I have left it in place. Upon further internet research I came across some builders that did what I did and some that left the shield disconnected.

3. The pcb has an incorrect print for C2 and C5. C2 is printed with a value of .22uF and C5 as 100uF. These printed uF values are correct as per the schematic, not the component number. The component numbers are back to front on the pcb.

4. Make sure you sand the paint away from EVERY mounting hole on the chassis. Not just the grounding points. I had irregular continuity until I did this.

Anyway, I'm sure all these points have been raised already. I just wanted to list them because they were crucial to the success of my build. Here's a link to some other useful hints.

http://messageboard.tapeop.com/viewtopic.php?printertopic=1&t=75231&start=0&postdays=0&postorder=asc&vote=viewresult&sid=858c4158f19883454ea4cb8c5a763f52

 

[hymentoptera]

...Secondly, there's no need for the 512-1N4148 Fairchild Regulator that's included in the cart....

I'm pretty sure the 1N4148 (it's a small signal switching diode actually) is CR11 in the Meter Driver circuit. It's rectifying the output of IC1 before being sent to the meter via R59 (the 3k6 resistor which you noted is marked 3k9 on the PCB).

 

[olla]

Is it possible to replace the output transformer of a finished 1176 rev G with the Lundahl LL5402 output transformer? If not directly possible, what changes would have to be made for it to work properly?

 

[David RP]

Hi Folks

First post here. I am just about to start building a Rev G.

I note from the MNATS BOM a suggestion to use a Bourns pot on the output (R23) The BOM shows a 100K log,
the Bourns recommended is 250K.  Why the value difference ?


David

 

[mnats]

I note from the MNATS BOM a suggestion to use a Bourns pot on the output (R23) The BOM shows a 100K log,
the Bourns recommended is 250K.  Why the value difference ?

From the BOM linked from the first post of this thread, I read:

1 100k POTENTIOMETER R27 OUTPUT, LOG

You can use any brand you like and as I always like to say the original schematic is your best reference.

 

[David RP]

Thanks for the info Mnats

I read that comment about the pot on the BOM at Hairball page 4 here. Maybe a typo ??

http://hairballaudio.com/bom/RevG.pdf

I will use the BOM from page 1 on this thread

David

 

[slaterweezer]

Hi guys. I finished wiring my Ref F and powered it up. All seemed fine and I left it plugged in for a little while. The meter went to 0 like it should. I then unplugged it and brought it from the work bench to the studio. Plugged it in and hooked it up to an insert. I got a loud feedback that went away as soon as the output was cranked to the max. Then I heard it passed audio. It was distorted and I got no GR. After about a minute of playing with it (hearing the ratio switches produce strange oscillations) I started to smell smoke. I fried R36 (100 ohms). Quickly unplugged it. Does anyone have any ideas? Did I fry Q6 & 7 as well? Thanks for listening!

Dan.

I realise this is an old post, but I had this situation too and in searching many posts and not finding an answer, I wanted to reply so hopefully others could benefit from my realisation.

It appears that R36 will burn on a rev F/G board when you get Q8 and Q9 reversed.

In my case, I was building 2 Rev G's and without noticing that Q8 and Q9 were complementary PNP and NPNs, I loaded 1 board with both NPN's and the other boards with 2 PNP's.

One board then measured only 10V on the 30v Rail, and the other was smoking / Burning R36 out.

Hope this helps others in the future.

R.

 

[EvLoutonian]

Here are the rev f. Schematics
http://mnats.net/files/1176REVFG_SCHEMATIC.pdf

Has anyone else been a bit confused that the above (linked) schematic shows some different values compared with the original UREI schematic (as well as the MNATS Rev J BOM) that I have been going off for my Rev F and G builds?

Namely:

        (Urei)    vs  (linked schematic)     

R21    6.8k    vs  7.5k
R29    1M      vs  6.8M
R32    2k        vs  1k
R33    11k      vs  4.7k
R34    3.9k    vs  4.3k
R87    1.1k    vs  120R
R89    220R    vs  2.7k

C10    0.1uF  vs  0.15uF
C13    100uF  vs  0.0022uF
C17    poly      vs  electrolytic?
C24 &
C25 &
C26    1000uF vs  2200uF 
C89    (none)  vs  10uF

My starting point was to order the parts suggested by the Hairball Mouser cart, which seems to follow exactly the above linked schematic.  But when comparing back a bit more closely to my original MNATS BOM, and then going back further to the definitive original Urei schematic for Rev F/G, I found the above discrepancies.

Some values I can see maybe would be OK either way (?), but a few are vastly different.
I would greatly appreciate if anyone can tell me which values I should choose for these components!

THANKS,
Evan.

 

[David RP]

Evan
I am just about to start building a Rev G. I just did a check against those components. Went a bit further and looked at the original Urei schematics for F and G and whats printed on the board. Got the following


                    Urie F    Urei G    Mnats Schem    Mnats Red F/G screen print

Pre amp  R21  6.8k      7.5k          6.8k                6.8k

Line amp R29  6.8M      1M            6.8M                6.8M
              R32  1K        2K              1K                  1K
              R33  4.7K      10K            4.7K                4.7K
              R34  3.9K      9.3K          3.9K                3.9K
              C10  .15uf    1.0uf          .15uf              .15uf
              C13  .0022uf  .001uf        .0022uf          .0022uf

PSU        R87    **        2.2K        120R              120R
              R89    **        220R        2.7K              2.7K
              C24  2000uf  2100uf      2200uf          2200uf
              C25  2000uf  1000uf      2200uf          2200uf
              C26  2000uf  2100uf      2000uf          2200uf

** don't seem to be used in the Urei Rev F. But the PSU circuits in Urei F/G and the MNATs are all slightly different designs so guess that's the reason for differing values.

The different values between the original F and G schematics in the Pre amp and
the line amp  Maybe someone else can explain

The MNATs Red F/G screen print board values follow the original Urei F schematic other than in the PSU

David

 

[EvLoutonian]

... I just did a check against those components ...

Thanks David!

That actually helps a lot - at least it's not just me going crazy.. (!)

I actually went back and looked at the original UREI schematics for their suffix "G" and also the suffix "K".

I've added the SUFFIX "K" component values to your table as an additional cross-reference, along with the values from the MNATS Rev J board, because these are what I needed to go back to in order to help me work out why I got into such a state of confusion with my BOM ordering for this project..    (and hopefully this info may serve to help others who run into any similar confusion)


                              MNATS F/G board        Urei F            Urei G          Urei K       MNATS Rev J
_____________________________________________________________________________________
Pre amp     
                  R21            6.8k                    6.8k              7.5k              7.5k              7.5k

Line amp   
                  R29            6.8M                    6.8M              1M                1M                  1M               
                  R32            1K                      1K                  2K                2K                  2K                   
                  R33            4.7K                    4.7K              10K              11K                11K 
                  R34            3.9K                    3.9K              4.3K*            4.3K              4.3k         
                  C10             .15uf                  .15uf              1.0uf            1.0uf              1.0uf         
                  C13            .0022uf              .0022uf          .001uf          100uf            100uf   
 
PSU           
                  R87              120R                    **                  2.2K            1.1k              1.1k (1w)     
                  R89              2.7K                    **                  220R            220R              220R     
                  C24            2200uf                2000uf            2100uf          1000uf          1000uf   
                  C25            2200uf                2000uf            1000uf          1000uf          1000uf   
                  C26            2000uf                2000uf            2100uf          1000uf          1000uf   

IC input
                  C30                6.8uf                  6.8uf            10uf              6.8uf            10uf
                  C31                6.8uf                  6.8uf            10uf              6.8uf            10uf


* R34 is difficult to make out on the Rev G schematic, but I believe the first digit is 4, not 9?  (ie. 4.3k ohms, not 9.3k). 
This is easier to read on the "K" suffix schematic (and being closer to the 3.9k on the other schematics, makes sense too, yeah?)



The reason I have ended up in this slight state of confusion, and cross-referencing rabbit hole, is that I'm using the MNATS Rev J boards to build a couple each of the Rev F & Rev G version compressors, and using the Hairball transformers rather than the Lundahl or OEP transformer options on the Rev J board.
So I'm comparing back and forth between the original MNATS Rev J BOM and the later UREI revision schematics, whilst also cross-referencing the Mouser BOM's suggested by Hairball to help me understand choice of component types and ratings etc.

From what I can tell (from the comparison table above) the MNATS Rev J circuit+BOM actually follows most closely the values on the Urei Suffix "K" circuit, rather than Suffix "F" or "G" (although it is very close to the "G", except for values C13, C24, and C26).

I had been under the impression that the Urei Rev's F / G, & also the MNATS Rev J circuits were all actually identical, component for component - besides the choice and orientation of transistors & the choice of transformers (and one or two resistor values directly relating to the Lundahl input transformer option).
But now I can see this is not exactly the case, as illustrated in the discrepancies in the values across the above table.
Being the newbie, I unfortunately only realised these discrepancies after spending the $50 or $60 on the wrong values for my Rev J boards because I used Hairball's Mouser order form as my primary template rather than starting from scratch.  My mistake - whoops!

So anyway, my main question now is..

Can I substitute in any of the components from this table's "MNATS REV F/G" column (that I have already purchased from Mouser) into my MNATS Rev J board builds, or do I need to replace some or all of the components to the Urei Rev K / MNATS Rev J values to really work properly with my boards?

Some of these component's values are not really that different all the way across the table (eg. R21, R34, C30, C31) whilst others are actually pretty markedly different (R29, C10, C13, R87, R89).

Specifically it would be good to know if I can substitute in the large 2200uF power supply caps which I have here, in place of the 1000uF caps's indicated in the Urei "K" / MNATS Rev J BOM.


Thanks!
Evan

 

[David RP]

Evan
Ok I see what you up against. I am building the Rev G on the Mnats F/G board. As I understand the only difference between the 2 is the IC input amp option on the Rev G and other than this the board component values are the same on Mnats F/G  but not as we see on the Urei Rev F/G. This is puzzling me now BUT I am going with the values as specified by Mnats F/G documentation . Just started building last night.

The Mnats Rev J seems to be a much earlier version based around the Gyraf G1176 and the board layout is different from  Mnats F/G

http://www.diyrecordingequipment.com/projects/mnats-rev-j-g1176/

More useful information here

http://www.mnats.net/1176.html

And the Rev J BOM  http://www.mnats.net/1176_bom.html

Forgive me if you have seen this info already. Cant help you with substitutions. Might it not be better to just get the new F/G board from Hairball at $28.00 ?

David

 

[EvLoutonian]

..
Might it not be better to just get the new F/G board from Hairball at $28?
David

Thanks again, David.
I have indeed been back & forth across the various resources & notes on both the Rev J & Rev F/G boards. The reason I've ended up on the Rev J boards is because I bought the boards already (x5 sets!) and they were sitting around here a few years already by now and it doesn't make sense to replace them all with essentially the same circuit for another $150 ($30 x5) expense.
Especially as I've already mostly populated all five boards by now.
I just didn't realise in time that these boards had the above component differences before I placed my order. I did look back & forth between between the various BOM's, but obviously not closely enough!
I guess the safest way to proceed is to replace where I have the incorrect value components from the table above with the correct values for my board & just count the additional expense as a lesson learned. 
I was just hoping someone here may be able to advise if I can actually use these three big PSU caps (C24, C25, C26) interchangably between the various version boards.  For example, I know when people restore old vintage valve amps they will often bump up the value of the cap's in the PSU these days. And it seems to be widely accepted that it's not only fine, but a good idea to do this. I thought it might be the same case here.
Prob wishful thinking either way on my part!
I'll ask my pal tomorrow whose building in parallel what he reckons.
Cheers!
Evan

 

[David RP]

Just about to wire the input on my Rev G
Is there not an error in the positions of the numbering of the xlr pins in this drawing. 
They are shown as
1Scr    3 to Minus
    2 to Plus

Should they not be
1Scr    2 Plus
    3  Minus

If wired in the positions  shown with a balanced input the phase would be reversed but if using an unbalanced input where pin 1 and 3 have been shorted would this not stop audio.

I know that for many years the standard was to use pin 3 hot in the USA and was probably the case when the 1176 was designed. Are we not all on Pin 2 hot now?

David

The only "trick" to the input wiring is the shield.  You really want these connections shielded and you want a continued shield from input XLR to the PCB input (but not connected).  Basically you wont the shield to capture stray signal and short it to ground at one end (by the XLR).

Id probably do this using the concepts here:
http://mnats.net/1176_reva-d_hairball_wiring_input.html

1. Run your shielded cable from your input XLR to the IC input.
2. Connect that shield to the shield of a cable with the two inner conductors connected to the pot.
3. Connect that shield to a wire connecting the other side of the pot and wiper to the INPUT of the circuit and leave the shield unconnected (per the wiring pages linked above).

I've never done this, but this looks right and should keep the noise out.

Mike

EDIT:  POT IN DRAWING SHOULD BE 10K INPUT.

 

[Echo North]

Pin 2 = +
pin 3 = -
Pin 1 = common

 

[David RP]

Firstly a big thank you to Hairball and Mnats for producing the case, pcb and sourcing the other parts needed to build the 1176. Easy ordering and 100% communication.

Just finished a Rev G today and pleased to report it worked and calibrated first time. No hum and very little noise with full output and all controls and functions work as they should.

A couple of questions :-

I have the IC input version. Can anybody help with the how to trim the CMRR?
I have just left the Distortion trim pot at 50% as I don't have any way of measuring this. Is it possible to hear it when adjusting the trimmer?

David