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

[envelope]

Another factor that me does not work is to put the switch of attack in off. I put the pin 22 to ground, but the VU meter not decibels decreased (gain reduction to put calibration). I have checked the unit...

Hi,

I'm not sure what you mean exactly, but have you wired your switch for the GR off/on as in this diagram from Skylar?

 

[armand1234]

No envelope, I do the calibration of Gain Reduction Meter but when I have to put the pin 22 to ground to simulate the Attack in Off, the VU meter no have changes. (To adjust to-10 dB). Sorry for my english!!!

Thanks!

 

[armand1234]

Ok now understand you! I have 3 connectors of the attack pot (DPST), but i have the rotary RATIO version. I connect the w of pad 22, cw to ground, and ccw????. Please i am lost!

Thanks!!

 

[StudioSQ]

I am building my third one of these and i am having a weird problem. Everything works as it should except there is a loud hum when the input pot in all the way down (max attenuation) that lessens quickly as you turn up the pot. the hum comes up when the unit starts at the same time as the GR meter comes up to zero.  I tried taking out the pot and wiring the IC input stage directly to the input of the preamp and it works fine with no hum. I also tried grounding the input pot everywhere i could think of, no change. I am at a bit of a loss, any ideas?

 

[mnats]

1-The C1 capacitor is specified with a 5% tolerance in the BOM but the Mouser project list provided a 10% tolerance devise. Any potential problems issues?

No.

2-Is it possible that the MNATS PCB designation for C2 and C5 have been interchanged?

Yes.

However, the component values and footprint on the PCB are correct.

3-R59 BOM value is 3.6Kohm and the MNATS PCB designation is 3.9Kohm. Which takes precedent? My choice was 3.6 based on the Schematic

This was mentioned earlier in the thread. As always, the best reference is the original schematic linked from the JBL Pro site. However, it's unlikely you'll notice any difference at all between the two values.

 

[[email protected]]

Here are a few more discrepancies I wanted to point out:
1-BOM identifies a 2N5457 as Q11 but I believe the PCB indicates Q10
2-Q's 12-13-14-15 are supposed to be 2N3707 according to PCB and Schematic. However the Mouser component kit is delivered with 2N3708's. The difference is DC Collector/Base Gain hfe Min: 2N3707 = 100 and 2N3708 = 45. Problem?

Thanks again

 

[Echo North]

Here are a few more discrepancies I wanted to point out:
1-BOM identifies a 2N5457 as Q11 but I believe the PCB indicates Q10
2-Q's 12-13-14-15 are supposed to be 2N3707 according to PCB and Schematic. However the Mouser component kit is delivered with 2N3708's. The difference is DC Collector/Base Gain hfe Min: 2N3707 = 100 and 2N3708 = 45. Problem?

Thanks again

1. Is my fault.  IIRC on the earlier versions it's Q11.
2. I put 3708's on the list because they have a higher hFE (over the 250 recommended).  I've always used the 3708's in my builds.

The BOMs were put together by me.  They are not endorsed or checked by MNATs.  There are a few discrepancies I need to correct.

Thanks!

Mike

 

[[email protected]]

The BOM notes recommend a different pot for the Output. I have two questions about this:
1-Why not include the Bournes part in the kit to begin with?
2-What affect if any does the value change have?

BTW, my build is coming along very nicely thanks to the great support from this forum.

 

[BigBellC]

Hey Guys,

are there different BOMs in circulation? The BOM linked in the first post is different from the BOM on Mnats page. Is the BOM in the first post newer than the BOM on Mnats page?
The Hairball BOM is different too..

Thanks a lot!

 

[Echo North]

The "official" BOM is the latest MNATS BOM. (check the numbering)

The "BOMs" on my site are links to mouser carts that are mostly right.  It's still up to the user to confirm them against the latest MNATS BOM.  if there is a discrepancy, the MNATS it correct.  I would also still encourage you to go through the HB BOM/cart and see if there are any components you may want to try or change to customize your compressors sound.

If you email the discrepancy to me, I will do my best to fix it, but it may take a bit.

Thanks,

Mike

 

[Songguy]

Hi all,
I'm a little frustrated now. I make it a point to search before I post but I can't find a direct answer.

Does the r55 "0" adjust on the gr meter driver amp section replace the need for the front panel zero adjust? I ask because mnats site uses the v. D board for the step by step which has pads for the zero connect. If I'm wrong please school me.

Thanks, chris.

 

[Songguy]

Hi all,
I'm a little frustrated now. I make it a point to search before I post but I can't find a direct answer.

Does the r55 "0" adjust on the gr meter driver amp section replace the need for the front panel zero adjust? I ask because mnats site uses the v. D board for the step by step which has pads for the zero connect. If I'm wrong please school me.

Thanks, chris.

 

[edanderson]

the zero adjust on the front panel and the null trim on the PCB are two different controls [EDIT: this only applies to rev E and earlier, the rev F and later have a different metering circuit with no null trim].  you will need to adjust both to do the calibration for any rev of the 1176  [EDIT: you don't have to do the null trim on the rev F and later because it doesn't exist].  the exact resistor part number for each of the two controls may be different from revision to revision, but the procedure is the same for all revisions.  watch the mnats calibration videos, they apply to all revisions.  also, download the original 1176 manual and take a look at the schematics for the different revisions, that can help you understand what the same controls are in the different revs.

http://www.jblproservice.com/navigation/Vintage%20JBL-UREI%20Electronics.html

ed

 

[BigBellC]

The "official" BOM is the latest MNATS BOM. (check the numbering)

Hey Mike,
thanks for your answer!

Is there any numbering on Mnats BOMs? I didn't found it...But I've seen, that the newer ones uses the LM317, so the BOM on Mnats page is the older ones. The BOM in the first post is up to date.
On yours the version is written

If you email the discrepancy to me, I will do my best to fix it, but it may take a bit.

I will go through the BOM and if there are discrepancies I will tell you, no problem!

I would also still encourage you to go through the HB BOM/cart and see if there are any components you may want to try or change to customize your compressors sound.

I've already maked a mouser cart, but with the older BOM  :-\ I didn't know that you have maked available the mouser cart..I will take a look ;-)

Why do we use FC/FM? I thought the NHG were the electrolytics for audio path par excellence ?! Or are the FC/FM better now?

Thanks!

Edit: What about the self-etch file? Is there any new version flying around? The version on Mnats page isn't up to date...

 

[Echo North]

Why do we use FC/FM? I thought the NHG were the electrolytics for audio path par excellence ?! Or are the FC/FM better now?

The Mouser carts on my site are pretty organic.  Mouser routinely runs out of the electrolytic and film caps so I'm always looking for a suitable "in stock" cap.  This is also the reason you may see some WIMA's rated for 100V rather then 60V in the cart.  It boils down to what is in stock at any given time.

As far as what's best for audio, opinions vary.  That's why I encourage people to use the Mouser cart as a guide rather then just click and order.

Thanks!

Mike

 

[Songguy]

Ed thanks for the clarification and manual link . Ive watched The calibration videos too, seems pretty straght forward. but I'm still having difficulty understanding how the front panel zero adjust should be wired. I'm still researching as you read this.

Chris

 

[Songguy]

On the mnats rev d board the 0 set goes to pads 16,15,17. Where are the equivalent pads on the rev f/g pcb?

Still looking.
C

 

[Nele]

Why do we use FC/FM? I thought the NHG were the electrolytics for audio path par excellence ?! Or are the FC/FM better now?

General consensus: NHG for powersupply, filtering and decoupling, FC/FM for audiopath.

 

[Echo North]

On the mnats rev d board the 0 set goes to pads 16,15,17. Where are the equivalent pads on the rev f/g pcb?

Still looking.
C

The 0 adj is wired to the 0 adj pads on the board (R55).  It can be a PCB mount trimmer or a panel mount pot.  Either way it's one or the other and it's 2k ohm.  15, 16 and 17 are for the output pot.

 

[Songguy]

Sorry mike, I meant 12,13,14 on rev D.

Do you mean r55 "zero adj" on rev F? R44 on F is a 1.5k resistor on the BOM, not seeing r44 on f board on the gr meter driver amp section.

Just want to be sure before I start soldering.
C