[BUILD] 1176LN Rev D DIY

[sr1200]

check the wiring on your input transformer next.

 

[David R.]

I am now popping fuses like candy.  Expensive candy.  No idea what he cause is, visual inspection checks out, I just can't get the unit to power on without popping a fuse. Was working fine for a few months.    I am using the 1/4 amp slo blow fuse.  Any ideas on what I should look at?  Thank you.  -David

 

[sr1200]

Try looking at your VR first (the part that has the big heat sink on it)  Make sure the heat sink isn't touching any other components. I assume the caps dont look blown (badly blown caps are fairly easy to detect with no testing equipment)
After that check your transistors and diodes.

 

[dbonin]

Resistors that are easy to misplace if you are NOT checking resistor values - you really must check each one just as you stuff them into the board for best results....
These are easy to swap even if you are checking!  Thought this might help someone...
10k vs 10M
R10 pre 10k
R31 sla 10k
R35 GRCamp 10k
R45 On Ratio Board 10M
R66 grmd 10k

150k vs 150R
R30 sla 150k
R58 R58 on Ratio Board 150R
R85 pre 150R

1M vs 1k
R13 pre 1M
R36 GRCamp 1M
R8 pre 1k
R81 PS 1k
R82 PS 1k

270R vs 270k
R4 pre 270R
R41 GRCamp 270R
R57 270k

3.9k vs 3.9M
R60 GRCamp 3.9k
R65 grmd 3.9M
R67 grmd 3.9k

470k vs 470R
R37 GRCamp 470k
R54 R54 Located on Attack Pot 470R
R61 R61 on Ratio Board 470R

560k vs 560R
R33 sla 560R
R62 ratio 560R
R9 pre 560k

** grmd = gain reduction meter driver section
** pre = preamp section
** sla = signal line amp section
** GRCamp - GR Control amp section
** PS= power supply
** ratio = ratio board

 

[Stagefright13]

germoju  Only guessing but thoroughly check your output transformer wiring. If you used screw terminals it will cover up the color legend on the board. So use the layout pic.

John

 

[Stagefright13]

And you are going into it with a Balanced signal? Not from A board send or something?

John

 

[TheWolfman]

Hey,

Projects rolling along nicely.

Just want to check that my powers wired up correctly just to be double-sure...better safe than sorry!

I've used an Avel Lindberg and I'm using a 240 input as I'm in the UK:

 

[Stagefright13]

The input side looks good coming in but can't tell what color output wires ya got...  2 whites?? A grey?? Maybe you have A different transformer.

John

 

[dbonin]

Basically do the meter tracking adjustment without adjusting the meter.

Do this ignoring the VU meter on the front.

Input = "24" mid rotation
Output = "24" mid rotation
Attack = full CW
Release = full CW
Compression ratio = 20:1
Meter mode = "GR"

1. Apply a signal (1 KHz, 0db).
2. Set output control for 0db as read on an external meter measuring AC volts across output XLR pin 2 and 3
3. Set attack full CCW (off position).  Set input control for +10db as read on an external
meter measuring AC volts across output XLR pin 2 and 3
4. Turn the attack control OFF (CCW) and readjust the output level control for "0" if
necessary.
5.  Repeat 7 & 8 until the output drops 10dB (2.44V to 0.775V) whenever the attack control is turned ON.

If you can do this, your unit is compressing and there is something wrong with the meter control section.

I can successfully measure 10db of compression using this method. I Re did all the adustments with trimmers starting mid way - same thing as before, no joy on meter calibration - r74 will not fall to 0V.

 

[Stagefright13]

Davidr try replacing the rectifier diodes if ya got spares. Just A guess tho. I honestly never got one of these things to work on A quarter amp slo blow. But use 50 VA transformers. Wich are bigger than necessary. But everyone else has success with them with the specified transformer. So I would suspect A problem. Double check your power caps are oriented properly too.

  You are using the transformer from Hairball Audio?

John

 

[David R.]

John and SR1200,

Thanks for your input.  Everything checks out, all Capacitors are in the right polarity, diodes are passing current one way only, transistors seem to check out.  Transformer is from Hairball. 

Let me know if I am going to burn down the house, but she is now running with a 500mA fuse instead of the 250mA that comes with the BOM.  Now i I could only get part 3 of the calibration working, I would have 2 up and running perfectly.

 

[Stagefright13]

Well I am glad you are up again. A 1/2 amp fuse WILL blow if something shorts. I don't think my studio insurance covers giving bad advice tho!!! After the Qbias adjustment is done the compressor is A fully working unit. The extra steps are only for the meter.

John

 

[sr1200]

I think i have half amp in both of mine.  As long as you're not putting like a 3 watter in there or something crazy.

 

[germoju]

germoju  Only guessing but thoroughly check your output transformer wiring. If you used screw terminals it will cover up the color legend on the board. So use the layout pic.

John

hi guys
shame on me... Yesterday I re-builded all my input wires... nothin'changed... my solders are good...
I found the problem : my patch OR my jacks !!!
When the 1176 is directly plug to my sound card the sound is great
So my "new" problem is not a 1176 problem !! YOuuuuuhhhouuuuUUUUuu !
Thanks again guys

 

[ILOVE1176]

Hey everyone

I need a little help and direction.

Where do I find the info regarding which resistors and  capacitor to connect to my attack and release potentiometers? I cant seem to find this info anywhere for my REVISION D BUILD.

Just confirm the following for me as well please.

Linear SPDT 25K Potentiometer = ATTACK (CORRECT?)
Linear 5M Potentiometer = RELEASE  (CORRECT?)

Thanks in advance.

 

[Edward]

Hey everyone

I need a little help and direction.

Where do I find the info regarding which resistors and  capacitor to connect to my attack and release potentiometers? I cant seem to find this info anywhere for my REVISION D BUILD.

Just confirm the following for me as well please.

Linear SPDT 25K Potentiometer = ATTACK (CORRECT?)
Linear 5M Potentiometer = RELEASE  (CORRECT?)

Thanks in advance.

Check the schematic, you'll find the values there.

Yes, and yes on the pots.

 

[ILOVE1176]

Thanks Edward!

Do you perhaps have a link to that schematic for me? Is it the PDF on mnats site? Ive gone through that and don't seem to see it?

One other thing I have noticed is my Input dial doesnt seem to go all the way round from 0 to infinity. Is this just how it is? Is the T-attenuator not eaxtly accurate with the print on the face?

 

[Edward]

Thanks Edward!

Do you perhaps have a link to that schematic for me? Is it the PDF on mnats site? Ive gone through that and don't seem to see it?

One other thing I have noticed is my Input dial doesnt seem to go all the way round from 0 to infinity. Is this just how it is? Is the T-attenuator not eaxtly accurate with the print on the face?

My pots are like that as well, i just aligned mine with "infinity". They don't go all the way but i don't see why i would ever turn them all the way up in normal use anyway.

It is the .pdf on Mnats site, and I'm 100% sure that it has been discussed before on this thread, try the search function. I know it can be found on the schem as well cause i remember i looked it up there...

 

[ILOVE1176]

I still cant seem to find the values of the resistors and capacitor that go onto my attack and release potentiometers???

I have no experience reading scematics drawings?

Help please anyone?

 

[Echo North]

I have no experience reading scematics drawings?

Now is a great time to start!

MNATs even labeled the pots to make it clear.