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

[Echo North]

Ohhhhh you got me, I just kinda glanced at it 

Perhaps there is a true rev AB schematic floating around that we're missing here.

Wish I had a rev A to check this out.

If you do change resistors/add jumpers let us know if you find a solution so I can update my docs.

Thanks,

Mike

 

[ethervalve]

I can send you a new set. Or even if you want to make a lorin switch board and just swap the whole assembly out.

Sorry I missed your message. but thanks, that was really kind of you to offer! I did, in fact, lift a pad on the ratio board, but I managed to work around it.
And thanks for the advice. I had a couple intractable problems, so I hired a great tech who lives nearby to look at it. He brilliantly and methodically quashed all the bugs.

It turns out that:
a) my biggest and most boneheaded error was that i had incorrectly wired the output transformers (that took care of the gain problems).
b) one of the two units required a resistor change in order to perform the null adjust step.
c) the other unit had a faulty trim pot.
d) Q1 (which i didn't bother to match) was giving sass on the 2nd one. Even after seemingly passing the Qbias step, it wouldn't limit. Socketing it and swapping in another fet did the trick.

it goes without saying that i probably should have attempted a simpler project... but now that it's done i love it.

I've only used the Purple MC77, never a UREI, but I find the revA clone compares quite favorably. So far I've run clean guitar, female vox and bass through them. They work great on all of these sources.

 

[orangerec]

I looked at the first schem off the jbl site and tried a change. I subbed out R63 which on the revA(Hairball) pushbutton board is 1.5kohm to a 2.7kohm. This forced me to recalibrate the Q bias but with no luck. The plosives live on. I put back the 1.5k to match the mnats boards.

 

[Stagefright13]

Hey ethervalve great to see your up and running! Awesome compressor 'eh? Mine was used on the close miced guitar and snare drum top on this project so far and sounds awesome.

As far as the nuke mode the original doc says if ya hear pops to back off the controls... But the nuke works fine on my rev d's. I will finally get a chance to goof with mine next weekend prolly. But it doesn't detract at all from it's awesome sound. This thing is a champ!

John

 

[stereokillah]

HI
it's my first 1776 clone and just to know, the parts no indicated on the bom REV A, like the pot for release, attack and output are same as the GYRAF REV.

RELAESE 5M LIN
ATTACK 2.2k LIN
OUTPUT 100k LOG

That's right?
Thanx

 

[Stagefright13]

I believe you want these:

Attack: 25K Linear Taper
Release: 5M Linear Taper
Output: 250K Log Taper

John

 

[stereokillah]

exactly Stagefright13
thanx for your Help.

 

[ethervalve]

Hey ethervalve great to see your up and running! Awesome compressor 'eh? Mine was used on the close miced guitar and snare drum top on this project so far and sounds awesome.

As far as the nuke mode the original doc says if ya hear pops to back off the controls... But the nuke works fine on my rev d's. I will finally get a chance to goof with mine next weekend prolly. But it doesn't detract at all from it's awesome sound. This thing is a champ!

John

Thanks John, I really love mine. I've only had a chance to test it on mix-down stuff but it's amazing how much limiting you can get away with while using this thing. I found 1:12 to be magic on female vox. All my drums are bounced down to one track so i haven't had a chance to try it on a discrete snare track--but i can't wait to.
Good luck on your manhattan project (ie debugging the nuke).
also, thanks again to mnats for taking the time to design these boards.

 

[Anonym]

Is it possible to see the specs of the Hairball-transformers? Is there a shop selling them in europe?

 

[Echo North]

Which transformers?

The power transformer is sold by Farnell in Europe.

The audio transformers are custom made by Ed Anderson and sold through me.  They are priced cheaper then you could find at any commercial store.  Even with shipping to Europe they are a great deal.

Mike

 

[0dbfs]

Getting close to completion on my dual RevA tat case...

Somehow I ended up short a 47uf cap in the GR section...  ???

It looks like a decoupling cap (C18, 30V to gnd just before 30V hits Q7). I wonder if a 100uf or 220uf would be fine? I've got a couple 25V 47uf's but felt the voltage would be too low.

Then it's on to wiring and a little bit of drilling in the case.

Cheers,
j

 

[Stagefright13]

Radio Shack sells them. Part Number 272-1027 . Just slap that in there and order good ones and solder wick it out later

But I'm sure ya got good ones by now I just looked at the posting date. I have NEVER gotten every part without another order or 2. So I feel for you!!!!

John

 

[outoftune]

hi.

just powered up my 1176 rev a. it's passing signal, i've only tested it on the scope with a signal generator, but has a couple problems.

1) the negative voltage is reading around  -4vdc instead of -10vdc. the +30vdc measures fine.
2) in GR metering mode, my meter does not go up to 0 or register anything. the meter works normally in VU mode

any suggestions of what might be causing these problems? i've double checked all the connections. im going to try to run some audio through it and have a listen this weekend

 

[Echo North]

Did you test the power supply before you stuffed the rest of the board?  If yes, has the -10 reading changed?

If you didn't check it before stuffing, check the values and positioning of the parts in the PS.

R81
R82
R87
R89
C23-26
CR6

The 4 recifier diodes and the VR are probably ok, but it never hurts to check.

I would get the -10 right then run the calibration.

Good luck,

Mike

 

[outoftune]

mike, thanks for the suggestion. i had one of the caps flipped the wrong way....now the -10vdc is working fine. i ran the calibration and was able to make it through all the steps in the video.

it's getting there, but i still have a minor issue.

i can get GR in 1:12 and 1:20, but when i put it in 1:8, the GR meter goes up and pegs at the max and won't move around. when i put it in 1:4, the GR goes back to zero, but it won't do any GR at all.

any suggestions?

 

[Echo North]

Are you using a rotary or buttons?

I would start by looking at your ratio board's resistor values and checking for shorts.

Start at the source and move backwards.

Mike

 

[outoftune]

Are you using a rotary or buttons?

I would start by looking at your ratio board's resistor values and checking for shorts.

Start at the source and move backwards.

Mike

im using a rotary switch. i will check the values and check for shorts. thanks again for the help.

 

[phatmateo]

Hey guys, I got my Rev A up and running, but I'm having trouble setting the GR to "0".  Its pinned left.  Stagefright mentioned that his meter was set beyond the trimpot's threshold.  Should I put a 5k trimpot in R71?  Or is there something else I should be checking?  Thanks

 

[spica]

Hi all,

I haven't built my Rev A yet but have had success with the Rev D and absolutely love it.  Many thanks to Mako and everyone else who contributed to these 1176 projects.  

I've put together parts lists for the A and the PSU through Mouser (mostly based on Jonathan's (Odbfs) very thorough spreadsheet and Mako's documentation) and have made the Projects "shared".   You can order those projects by entering the Access ID under the EZ Buy tab on the Mouser website.  They are:

PSU - 7caffd020e
Rev. A - d678146727

I believe these are pretty thorough, but use at your own risk.  Some things to note:

Rev. A - I did not include the on-board Power Supply components.  I included both the attack pot with the off switch and the one without - not sure which I want to use yet.  The Ratio switch is the Alpha switch from the Mnat's site to use with SLAM mode.  I put in extra quantities of the transistors (except the 2N3053) and included both the 5088's and 3707's as I used the 5088's on my Rev. D's for anything needing a high HFE and the 3707's for everything else.  The quantity of the 2N5457 is 25 to allow for a sufficient population for matching.  The project has quantities for one channel.  

PSU:  I did not include the LED's or the resistors to the LED's (I don't use them).

I'm ordering mine now, so I will update the projects if there are any corrections.  Let me know if you use them and have any suggestions or corrections.  

-Tony

EDIT:  Rev A project updated - I had missed the 2N3053 and ordered the wrong sized cap for C27 and wrong header pin connector.  Fixed. 

 

[Stagefright13]

I used a 5k for R44. When I first powered up mine the GR meter was pinned to the left. I fiddled with ALL the trimmers including the bias and it came up just fine. At first I started troubleshooting for a wiring error etc.