[BUILD] 1176LN Rev D DIY

[SaMpLeGoD]

Hi, I'm building mine with the pushbuttons and the 25k Lin Attack pot with SPDT switch! wired as Mike said in his specs... 22 to the center lug, the CCW to the Black on Ratio board and the other to the Green on the Ratio board also.
THe Q Bias Adj and the Null (R75) trim calibration, I did perfectly and my 1176 accept all that regulations at it should be! but after that, when I put back the jumper to get R44 on the circuit again, my meter drops to the left, and I can't regulate anything after... the tracking trimmer, I Adjust and the meter just rise a little bit just before the trimmer ends... I move the input and out put knobs and they do the same, rise and fall the output level, that's it, when it's supposed in GR mode when I start rising the input and reaching the Threshold point, start to see the compression on the meter and on the output...
When I hit the ratio board, I see the sine wave just reducing a little bit as it should be, from 4:1 to 20:1, and when I hit all the buttons the VU's indicator rise to the hard right, and this is right! because I'm putting the fet in a "bad biasing way! and this happens in my others 1176 and on the original too... I'll post some photos tomorrow! maybe this helps a lot!
Ahn.. one thing I notice is that in the MC76 schematic all the 3707 are changed by the 2N5088... but I have the 5088 only from Q7 to Q10... I'll try to swap all the 3707 with the 5088 and see what happens!

Cheers,

Eddie  :-\

 

[Stagefright13]

It may also help to install R44 with it set to the middle position for a start. And if you read Mnats site at the end of the rev D documentation it is noted that 2 resistor values on the overlay are incorrect. The correct values are listed there. Dunno if that will help any but worth a shot.

And the 3707 or 3708 will work just fine if the hfe is over 250. I wouldn't change them for no reason. The problem likely lies elsewhere.

John

 

[SaMpLeGoD]

The R15 and R64 are ok with the values... I think is not the problem with starting R44 at the middle... I change the R44 all the way up and down and no indication is shown... must be something in the GR control, 'cause when I hit the GR button, it puts pad 28 and 29 directly to the VU Meter, and it works with the jumper off (taking R44 off the circuit) with that jumper of I can regulate the "0" point, when I stuck back in position... the pointer falls down to the left and nothing happens...
I tried to change the 5088 by the 3707 all of them whatever hfe, and it stills the same... there's something in the circuit that is not working propertly... well... Still searching

Eddie  ???

 

[khstudio]

Is the GR Disable button on the PURPLE units the same as thing? I don't have a switch on that units Attack either.

I just looked at the Purple schematic I have & it IS the same as the switch as the original "Attack Off"... so that's cool.
That unit sounds GREAT.  ;D

After seeing were it is on the schematic I have a better grip on how to implement it on the MNAT Rev D.
... still need to check out the video too.

Opps  :-[
It seems it's the same as the "Bypass" on the G & Mnats Versions & disables the VU... so, you still have to do the "Shorting thing" like in the video to keep the VU active.

That video is helpful  ;D

 

[SaMpLeGoD]

Problem Solved!!!!

I had a bad 2N5088... and other has a bad contact... now all is working propertly!!!! I just need to check why I'm getting the input signal with the phase reversed... maybe some bad connection on the Input attenuator or with the Lundahl's input connection  :-\
But it sounds amazing, I think is more clear than my REV J one... I'll check after the Christmas in the Studio
Thanks all of you!
Happy Christmas!

Eddie  ;D

 

[Echo North]

Awesome!

Congrats Eddie.

Hope to button up my pair in the next week.

Mike

 

[SaMpLeGoD]

Thanks Mike!

Hope to see yours working too! It's a very nice comp I must say

I'll put some photos afterwards

Happy Christmas!

Eddie  ;D ;D ;D

 

[nielsk]

Which 5088 was bad? I have one with a similar problem, I can adjust the meter with the link out an 0 the votage across R74, but when the link goes back on, the GR reading drops way down. I can bump it back up by cranking up the offset, but then it is way off 0 volts.... 
BTW, I use the attack pot / switch combo on all of mine, I do not prefer the off switch on the meter thing

 

[SaMpLeGoD]

Hey Nielsk,

Double check if your 5088 are in the right position... I'm talking about the Q7 to Q10 (Gain Reduction Stage). The boards from Mntas has a extra pad to you to put the 5088's, my first mistake was to ignore that step at the first time... and put the same way you should put the 3707... it's wrong, they has different pinout!!! the 3707 is E-C-B the 5088 is E-B-C so you need to put the 5088 in the way that you have the middle leg in the extra pad! what's happening to you maybe is what happens to mine... I adjusted easly with the jumper off, but the pointer falls down to the left when the jumper gets R44 back to the circuit.
Try that... I realize that after reading the META, then I notice a bad 5088 and other with a bad contact! fixed that, all running
Happy Christmas! hope this help

Eddie

 

[Stagefright13]

That's awesome ya fixed it Eddie. What a great Christmas present to yourself! 
I have my new one all done but of course after ordering 80 small parts from mouser and digikey I missed the .0047 cap... they wanted $40.00 for overnight so I stuck to ground shipping lol. Be here Monday.
Hope you enjoy it. I am using my first one right now. It gets lotsa miles and keeps on ticking.

If the phase is reversed just switch the wires. But I'm sure you already know that.

 

[SaMpLeGoD]

Hey John, yeah, I swap the wires from the input trafo! and now it's full throtle! hehehehe...
Sorry for your cap that you forget ordering... It's very bad when that happens!
Happy Christmas for everybody!

Eddie  ;D

 

[Stagefright13]

Don't worry all is not lost. My girlfriend wrapped my hairball order for stuff and got it today. Also I switched out 3 resistors on my original one and re calibrated. So needs a long "burn in" just in case

I did notice tho that as in the original 1176 doc from Urei the 0 set point can drift up to 1 DB. And this is true on the clone. It does the same thing. I believe this is a temperature thing. I originally calibrated the zero with the lid off the case. This time I zeroed the meter after leaving the lid on. After all that is real world. And after running audio thru it all day it has a VERY stable 0 VU.

I would suggest running it with the lid on for several hours before a final adjustment to the 0 trimmer. I turn my stuff on WAY before a session so 10 to 18 hours is normal. So should be the calibration. But don't touch anything but the zero set. The other trimmers will hold fine. That's why the original has A hole in front to adjust 0. 

 

[Stagefright13]

Missing 1 cap but close!!!!

 

[Stagefright13]

And I can't imagine how much work it took Mako to make this... And to make it to work so well!

Merry Christmas Mako your super hard work is WAY appreciated! And I am sure is appreciated around the world.

John

 

[Stagefright13]

Just make sure you wire it rev1 or rev 2 depending on board there are some wire differences such as Matta said in the out tranny?

 

[etevelurblomst]

Hey, i was hoping anyone could be a little helpfull on this one. I`ve built the mnats 1176 rev d clone, and its working and compressing etc etc, but the output from the transformer has too high impedance, so the compressor will only work if you put it in line inputs designed for high impedance, such when you put a bassgitar straight in etc..

Does someone have a good idea on what to do, im pretty sure i hooked up the trafo correctly, so maybe the fault is further down the line?



if you put the comp. into a regular line input --  some form of positive feedback occur, going from the output and back into the circuit..

someone with a clue?? or something to do to eliminate problem sources?

 

[joe-electro]

Hey, i was hoping anyone could be a little helpfull on this one. I`ve built the mnats 1176 rev d clone, and its working and compressing etc etc, but the output from the transformer has too high impedance, so the compressor will only work if you put it in line inputs designed for high impedance, such when you put a bassgitar straight in etc..

Does someone have a good idea on what to do, im pretty sure i hooked up the trafo correctly, so maybe the fault is further down the line?



if you put the comp. into a regular line input --  some form of positive feedback occur, going from the output and back into the circuit..

someone with a clue?? or something to do to eliminate problem sources?

Look for bridged traces around the input transformer and output transformer.

 

[etevelurblomst]

Could you please ellaborate? im from norway, so electronics terms in english gets me sometimes..

By bridged you mean?

 

[matta]

Could you please ellaborate? im from norway, so electronics terms in english gets me sometimes..

By bridged you mean?

This happens when you accidentally 'short' pads together, causing a 'Bridge' between those connections. Sometimes a bit of solder accidentally joins two different parts of the circuit together. Hope that helps.

Cheers

Matt

 

[Echo North]

Well here is a cautionary tale...

I finally got all my pieces together for my REV D V2 1176, which I've been building over 3-4 months as time/money has allowed and I was ready for the final hook-up.

I printed the schematic so had it on record along with the original schematic for the UREI Rev D and thought I was prepared for things... but...

I noticed having soldered the screw terminals on the PCB it covered up the colour coding for the output transformer... no problem! I'll just print it out as it is laid out in MNATS beautiful document, so I do and wire up accordingly...

The big moment arrives, I flip the switch BRIGHT lights and flames as R32 goes up in smoke... hmm funny, I had checked my wiring all looked good, voltages were good, what went wrong?

So I desolder it and then work backwards... but wait R32 was going to the wrong winding.... something is fishy... I open up the MNATS REV 2 document and the output transformer colours DON'T match the board... penny drops!!!!

I had BOTH the REV1 and REV2 manuals of MNATS and while I was working from the correct schematic for REV2 and the UREI one (which is great since it shows that you have to join the CT Orange and Yellow wires together if you have Ed's transformer) but the OVERLAY was REV1 which DOESN'T match up with REV2 (Mako you may want to add this to your list of changes to your REV D site in case anyone else makes the same blundering mistake!).

Oh man +1 on this Matt.  I read the first line of your post a few weeks ago and nothing else.  Turns out I did EXACTLY the same thing!

I've never seen a resistor evaporate so fast.

My new years resolution: when I see a post starting with "Well here is a cautionary tale..." I will read the whole thing  ;D

Oh well all is great now!  Will post some pics when I get my front panel.

Thanks,

Mike