[BUILD] 1176LN Rev D DIY

[pittsburgh]

Right, but what I'm saying is that I don't have a 5M pot anywhere.

 

[sr1200]

Well, then it would seem that you don't have a wrong part... just a missing one. 
Sucks when you have to order ONE part... shipping is usually more than the part.  Done that more times than id care to admit.

 

[pittsburgh]

  Should I take off the metal guide grooves off of the attack potentionmeters so that the posts will screw in flat to the front faceplate? Currently the guide, the metal piece that sticks out towards the top of the pot, is prevent me from putting the attack pot in at a straight angle.

 

[sr1200]

Why not, doesnt hurt the pot at all.  If you want to re-enforce the pot, you can drill a little hole for it to go into (without going thru the front panel), but being that theres not a lot of torque going on there.. probably not needed.

 

[pittsburgh]

  Do I need to solder the orange and yellow wires from the output transformer to one another? I've seen both answers here on this forum.

  Thanks,

  -P

 

[Echo North]

Ya solder them to each other and nothing else.  This is the start of one winding and the end of the other.  You're making a series connection.

 

[pittsburgh]

Should I also connect the bare stranded wire attached to the face of the output transformer to chasis?

 

[pittsburgh]

What points should I be wiring the 0 adjust pot to?

 

[TheWolfman]

OK so after carefully matching all my Transistors it now appears (on my scope that is) that the black beauty is passing audio, but my meter won't budge!

With the vishay trims it's hard to tell what is closed and what is open,in any case theres still no movement on the meter whatsoever.......also when switching the meter into GR mode the meter doesn't flip to zero like an 1176 should.

Any ideas?

Thanks peeps.

 

[earth tones]

What points should I be wiring the 0 adjust pot to?

On the MNATS BOM, the Zero Adjust Pot is designated as R71.  So the pot connects to the PCB at R71...it's also labeled ' "0" Set '.

 

[earth tones]

Well, I've completed my build and have managed to successfully calibrate my Rev D as demonstrated in the wonderful MNATS calibration videos.  Now I am wondering about the Distortion (R86) calibration.

I searched the thread and found:

Quote from: canidoit on July 02, 2009, 04:02:30 pm
Whats the calibration procedure for the distortion trimmer? I was turning the R86 trimmer and I am not sure what the normal setting for this is?

It's the preamp linearity setting. Usually setting it approximately midway will be sufficient, however if you want to set it correctly them you will need to invest in some equipment (at least an oscilloscope, signal generator and THD measuring setup). Apply a 500Hz -30dBu signal to the input, set the input to fully CW and the output to about 2 o'clock and measure the THD of the output. Tweak R16 for minimum THD.

Apparently, I do not have the necessary equipment.  If R86 is in circuit, can you still accurately guage what midway would be by measuring resistance?  I know that measuring a resistor while "in-circuit" will result in a reading that reflects resistance from other components in the circuit.

Thanks!

 

[TheWolfman]

Freakishly I was just checking continuity between various points on the meter board and the meter itself and all of a sudden the meter has come alive!Although absolutley no wiring or connections have changed!

Anyone explain what could possibly have been going on?!

 

[TheWolfman]

I am slowly wondering whether there's actually anyone looking at this board anymore...... ???

I am currently doing the calibration procedure after as previously posted,my meter simply just came alive out of it's own accord!

I have set the "Q Bias adjust" as per the instructions:

1khz Sine wave Input

Ratio set to 20:1

Output dial at -15ish

Meter in +4

Compression on Attack switch set to Off

I then raised the input level to get +1db on my Meter and then used the "Q Bias Adjust" Trim pot to bring this back down succesfully to 0db on the meter.All good.

However when attempting the next step and adjusting the meter in GR mode with the null adjust I can only get the meter to move maybe from-21 to -20 at the most using the front panel adjust and the "Null Adjust" Trim.This is using the shorting jumper.

I suspected that I may have a faulty Trimmer for R75 Null adjust so I switched it out for another (this time a 5k as thats all I could get quickly,but I figured this would suffice) but still to no vail.Reading the voltage across R74 it reads a constant value of 2.65V which is then not affected by any adjustments made to R75 Null Adjust.

I really really would appreciate some assistance with this from someone more experienced with this on here than myself as I feel soooooo close yet so far!

 

[earth tones]

WOLFMAN, simmer down and remove your finger from the "Post" button.  It's nobody's obligation to check this forum every hour to see if questions need to be answered. You may have noticed that I asked a question, somewhere amidst the barrage of posts that you have made today, that has yet to be answered.

Some friendly advice, considering the raw amount of data newcomers have to parse through with a thread of this size....summarize your issues/questions in your mind and then succinctly make a single post to the board.  Be patient and await a response.  Please do not litter the board with multiple posts.  If need be, please modify/edit an existing post to add more info.  Those of us who are also posting questions would appreciate it if they aren't buried behind a stream of posts from one individual.

That aside, experienced builders are more than gracious with their time and knowledge on this forum. 

 

[TheWolfman]

Earth tones.

Thanks and duely noted but I was simply wondering as I hadn't had a reply to ANY post in over a week and am in no way implying that the contributors here aren't gracious with their time and believe me there expertise and the very fact that they take the time to share it is more than valued and appreciated.

After having trawled through this entire thread I have not found any one with the same issues as me and am thus attempting to get to the bottom of it,which if I'm not completely delusional is the purpose of this support thread is it not?

 

[Ilya]

However when attempting the next step and adjusting the meter in GR mode with the null adjust I can only get the meter to move maybe from-21 to -20 at the most using the front panel adjust and the "Null Adjust" Trim.This is using the shorting jumper.

I suspected that I may have a faulty Trimmer for R75 Null adjust so I switched it out for another (this time a 5k as thats all I could get quickly,but I figured this would suffice) but still to no vail.Reading the voltage across R74 it reads a constant value of 2.65V which is then not affected by any adjustments made to R75 Null Adjust.

Check that your Q12 and Q13 are oriented properly and are in good shape. They also need to be matched within 10%. Also check that R79, R67-R69 and R76 are correct values.

 

[TheWolfman]

Hi Ilya,

Q12 and Q13 are both matched to within 2% and all the resistor values are correct.I did notice that when the Emitter leg of Q13 is shorted to ground that the meter jumps to +2?I don't know whether this sheds any light on the matter?

 

[pittsburgh]

  I'm having an issue with the gain reduction tracking meter adjustment calibration. I have the Rev D Version two board running inside of the hairball case. I've set up the compressor with a 1K 0dbu tone running to the input. I zeroed out the GR on the meter before adding the input signal, and zeroed the meter while set at +4 with the input signal. The problem that I'm having is that I'm not seeing a drop in the output when I engage the compression. While flipping the attach knob from off to one I see no reduction in the meter. The other two calibration tests went well, and I believe I executed them correctly, but I don't seem to be getting any reduction on the meter or at the audio output when I listened. Where do I start?

  Thanks for the help,

  -P

 

[sr1200]

seems like a lot of people are getting stuck on this part lately.  Check back a few (5 or so) pages and read forward, you may get the answer your looking for!

 

[earth tones]

While I have not adjusted R86 at all, I am very happy to report that my 1176 is passing audio beautifully and that all parameters seem to be functioning as expected.  I can't thank MNATS, Hairball Audio and all of the helpful members of this forum enough for making this build process so enjoyable.  I'm very grateful to you all.

Also, is there no "All-In" mode possible with these Ratio pushbuttons??