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

[danjpiscina]

Hi guys. I read through this article but haven't been able to find out if anyone has had to opportunity to compare mnats' Blue Stripe to an original. I'd like to do this since I have access to an original but it would mean I need to build one first! Any ideas?

After all, it is a rather big project to consider. If it ended up sounding nothing like the originals (even though the originals differ slightly from unit to unit), I'd rather build a rev D or something.

 

[mnats]

I just finished calibrating the blue stripe with a multimeter
and it seems okay except half dB above zero on the meter output
could be the resistance of 3.6K?
I saw that you were talking to a 3.9k resistor to +4 (hairball VU meter) instead of 3.6K. 
Right?

Sorry, corrected my mistake above regarding the resistor value.

Your multimeter measures voltage accurately at what maximum frequency? What frequency are you using to test?

 

[ilfungo]

I used a sine wave at 1000 Hz
0.775V measured on input XLR  pin 1 pin 2
correct?

the signal is rotated 180 degrees, I have to reverse pins 2 and pin 3 on XLR out?

thanks

 

[Matthew Jacobs]

Sorry if this question has already been answered. I tried to read the whole thread but couldn't find a answer.

The BOM posted in this thread calls for 1/4W resistors. The schematic calls for 1/2W resistors.

Is it OK to use 1/4W resistors? Has anyone had issues with 1/4W resistors? I know someone had distortion issues with 1/4W resistors on their LA4A, so is it best to stick with 1/2W with all UA gear?

I already got quite a lot of 1/4W resistors, so if they work for this project I'd prefer not to order more 1/2W resistors.

I'd appreciate some help.

Thanks

J

 

[spica]

Hi Matthew,

I used all 1/4 watt resistors with mine (as well as my Rev D) and have not had an issue.  I believe most people build them with 1/4 watters.  The only bigger resistor is the one in the power supply section - it is marked on the board I believe. 

-Tony

 

[Matthew Jacobs]

Hey Thanks Tony.

That's really cool. I can start stuffing my boards now and I don't need to order new resistors.

Do you think that the schematic says 1/2 W because that's all that was available back in the day?

J

 

[regularjohn]

Is the seperate psu board for the Rev A the same as the seperate psu boards for the other rev's?
They look similar, but without seeing a schematic I don't feel confident making that call.
I have a spare Rev A psu board that came with the Rev A pcb set, and I'm thinking of building a stereo Rev G and using that PSU board.  That should be fine, right?

 

[regularjohn]

Ah...nevermind.  found the answer.

 

[muffy1975]

Hey there again,

Now R14 should have a 22k resistor right!!!!

Question however...

Do I wire the t-pad to the inputs of the input transformer PCB board and the outputs to the main PCB?
Which way around does the input trannie go? Does the dotted side with the writing on face towards the input side of the transformer PCB?

Thanks

Michael

 

[regularjohn]

I can't remember which side the dot faces, but look at the input transformer and see which pin the shield connects to.  Then look at which hole on the pcb connects to ground.  Match the pin that connects to the trafo shield, with the hole in the pcb that goes to ground.  Simple.

It should go XLR input -> tpad -> input trafo -> pcb

I think there's a wiring diagram a few pages back.

R14 is 22K according to the component overlay.  That's what I used for my Rev A and it works great.

 

[muffy1975]

Hey Regular John  ,

that's what I have done RE:- the input transformer. I have wired it correctly. Thanks for that my man. I knew I had the right!!!

I have built 4 G1176's from MNATS before but I'm not great with schematics.

My trouble appears to be the wiring diagram. I'm using hairball meter and ratio PCbs and they don't seem to go together with the wiring diagram that's going around!!

Especially considering I am using a normal 25k lin pot without the switch.

Anyone know what to do?

The good news is that the ouput trannie hasn't blown any resitors and the external PSU is passing +30 and -10 well.

Basically is the stereokillah wiring diagram correct? It's confused me.

Does green go to pad 22 on the main PCB? Is the attack switch wired correctly?

HELP please team REV A.  :-[

Michael x

 

[regularjohn]

Yeah, I used the hairball pcb's and meter too.  I know what you mean that it's confusing - I don't know why some of the leads are numbered and some are named as colors...and some are both!  WTF!  They should just all be numbers.  Anyway, the wiring diagram that came with the hairball stuff is what you need to follow.  It has instructions for wiring a normal attack pot with a seperate bypass switch.

The stereokillah diagram is correct, but his diagrams of the hairball pcb's don't have the solder pads in the correct places, which can be misleading.

But yes, green does go to 22.  black goes to ground.  refer to the hairball documentation to be sure you know which solder pad is which.

 

[muffy1975]

Hey there gang,

got it going. The 33pf cap had failed for no reason, hence no sound. :

The wiring seems fine.

My meter is broken though The + tab came out of the back of the meter. Is there anyway of fixing these meters or are they sealed?  I haven't yet had it working so it's hard to know if it's fixed ( I pushed the + tab back in ) what with all the set variable resistors on the main PCB to set up

The unit sounds SUPER great though. ;D

A little confused about how to wire up a bypass. Looking at Hairballs instructions do I  take though leads 22 black and green back to the main PCB or to the ration board? Is black the ground on the main PCB? :


Thanks Rev A Team :

 

[muffy1975]

Hey,

in fact 22 and Green are the same things on Stereokillahs diagram. What's going on?

Is the idea to short 22 and G on the main PCB from the spare interlocking switch?

Michael

 

[Echo North]

My meter is broken though The + tab came out of the back of the meter. Is there anyway of fixing these meters or are they sealed?  I haven't yet had it working so it's hard to know if it's fixed ( I pushed the + tab back in ) what with all the set variable resistors on the main PCB to set up

Was it do to heat (soldering) or some malfunction?  There are + and - wires inside the meter attached to the pivot, they connect to the tabs in the back (with the rectifier diodes between).  Placing it back in may work, or you can try popping off the front, unscrewing the pivot supports and then reconnect the wire to the tab.  Do this on a clean surface free of metallic debris.

Although if it's a faulty unit I will be happy to replace it...just send me an email.

A little confused about how to wire up a bypass. Looking at Hairballs instructions do I  take though leads 22 black and green back to the main PCB or to the ration board? Is black the ground on the main PCB? :

If you want a clearer look at this part of the wiring have a look at the Mnats pushbutton wiring page:
http://mnats.net/1176-wiring-pushbutton.html

The example is a J board, but this part of the wiring is the same for all of the units.

I believe your bypass switch (wherever that is) should connect to BLK and GRN on the ratio board and 22 on the main board.  When 22 and BLK (ground) are connected you are in bypass.  When 22 and GRN are connected you are in GR mode.  These are the designations given on the original schematics.

Thanks,

Mike

 

[muffy1975]

Dear Mike ( Mr Hairball )

your Hairball kit rules!!!! ;D

I.....broke the meter and your instructions helped me to fix it. BANGO. It works again.

My confusion with the bypass stems from the fact that the attack pot  ( in Sterekillars wiring diagram ) goes to 19 on the main PCB and that on your Ratio board it asks for the attack pot (GRN ).

I have wired 22 from the main PCB to the Attack Pot ( GRN ) on your ratio board. Is this correct? I am using a standard non SPDT 25k pot.

Other than that...

I am passing audio and compressing....but just still a little unsure about where 22 from the main PCB goes. At the moment it is going to GRN on the ratio board. The shield of 22 is going to ground and then going to BLK on your ratio board.

Gonna check the mnats push button tutorial.

Many thanks Team Rev A for making this almost a no brainer ( good considering I don't really have one )

Michael de A 8)

 

[muffy1975]

Team Rev A,

Well the wiring diagram works.... This Rev A Rocks.

Got the meter in GR going. HAD TO USE 2n5088's in this section with a 5% tolerance on the ol hFe.

Discreet meters make the units sound better ( joking ) ;D

Let's hope Mako prints some boards. Can't believe there is a lack of demand.

Is Mako the new Steve Zissou. 8)

Now that I'm finished I'm gonna make me a latte.

Hope I can help other folk with this project. Note this is really easy as far as DIY goes.

XXXXXX

 

[muffy1975]

Oh team,

here are some pictures

notice the close up of the 2n5088's and how they are positioned. Mako's close up of his Rev D in the pdf also varifies how these components are mounted in place of the originals ( which sound way better ) so only use the 5088's in the meter section if you must.

Peace in the middle east

XOX

 

[regularjohn]

Is Mako the new Steve Zissou. 8)

Haha!  That's one of my favorite movies!  ;D

 

[phatmateo]

I only see one picture!