All things G1176 - the new "repost" thread.

[emreyazgin]

I would check all of your transistors. I ordered two different transistors from mouser and the data sheets were wrong. Shocking I know . Any who, you can use you DMM and the diode tester to easily check the orientation. Here is a link on how to test.

http://www.kilowattclassroom.com/Archive/AN0007.pdf

I kept frying R35 and Q5 was getting super hot because Q9 was the wrong way in.  

Just checked using the method in the PDF, they are ok, I haven;t check ALL of them, only the ones around the output drivers for now, as I have the problem of heating up of the drivers. Both the health of the transistors and the orientation seem to be fine.

 

[casrec]

sorry, mistaken what you said.

 

[W DeMarco]

OK Ive gone through all of my interconnects which look fine, and my unit is grounded as follows.  IEC ground to chassis, pin one of XLR input to chassis(These two grounds connect too the same point next to tranx about 8 inches from the XLR), center tap straight to pcb.
I am using a mnats board and made use of the G(ground) pad on the main pcb as documented in his wiring guide.  I am still getting a horrible buzz.  My main voltages are fine(30, -10).  Again this buzz gets louder as I turn up the output pot but in the center of travel it all but goes away then continues to get louder as I pass center.  The input pot affects this buzz slightley. 

Also noticing the release is affecting the meter in GR mode with no signal injected.  As you turn it CW the needle travels to the right many Db.  I've read thru this thread twice now but have not been able to find a solution. 

Any help is greatly appreciated!

Will

 

[extremewillis]

Hi all,
Hi all,

I'm going to start stuffing my Mnats Rev J board tomorrow.  I ordered the following semiconductors from Mouser; some of them had extra letters attached to the end that I don't understand, can someone let me know if any of these could be a potential problem?

for 1N4003: ON Semiconductor 1N4003RLG
for TL071: Texas Instruments TL071BCPE4
for NE5532: Texas Instruments NE5532APE4
for BC560: ON Semiconductor BC560CG
for BD135: ON Semiconductor BD135G
for BD136: ON Semiconductor BD136G

Any advice would be appreciated!  Thanks!

 

[jdbakker]

I ordered the following semiconductors from Mouser; some of them had extra letters attached to the end that I don't understand, can someone let me know if any of these could be a potential problem?

When in doubt, check the data sheet.

At first glance your alphabet soup refers to things including
- DC precision
- transistor gain grade
- RoHS compliance (ie: lead free, and then some)
- commercial temperature range
- DIP package
- supplied on tape (as opposed to loose in a bag).

While I don't know all the constraints and recommendations for G1176 parts by heart, none of these jump out at me as being unusable and/or dangerous.

JDB.
[was ordering parts just yesterday, and found one with a "-Q27A"-suffix. That was new to me, but careful reading of the data sheet showed that this meant that when feeding the taped transistors into an automatic placement machine the emitter would come first. Nice to know if you're doing a large production run, irrelevant for the DIYer]

 

[extremewillis]

When in doubt, check the data sheet.

Thanks for the advice - most of what I needed to clarify was right there in front of my face 

 

[emreyazgin]

With great helps from everyone especially Geoff, I have solved the problem, I knew it was a stupid thing..I forgot to solder one leg of a diod that was next to the output driver..Now I have checked all voltages and all transistor voltages match the ideal voltages ) One happy man!! Thanks guys

 

[emreyazgin]

One thing I still couldn't figure out though...The 6 position lorlin..Why 6 positions where only 4 ratio settings are present? Am I missing anything?

 

[cadsound]

Hi,
I've just finished building an 1176LN REV J MNATS Board using Hairball Audio's Kit.  I have also followed the Rev F-J BOM and Schematic.

I very confident that I've wired it correctly, as it passes signal well and cleanly and the input and output controls work as they should, however, it won't calibrate and does not show any sign of compressing on the meter.  The meter moves with signal content (1kHz signal as required for calibration)

I have the voltages at each transistor reading as they should, and I can't understand for the life of me why it won't calibrate.  The wiring is correct, as I stated previously and the only pot on the board that seems to work is the tracking pot but only for GR metering but it won't go to 0vu.

Thanks in advance for anyone who has a suggestion.

Carl

 

[a2d]

Hey Caral,,

check pad 18 there are 2 spots make sure its connected to the wiper of the bias trim pot.

Hi,
I've just finished building an 1176LN REV J MNATS Board using Hairball Audio's Kit.  I have also followed the Rev F-J BOM and Schematic.

I very confident that I've wired it correctly, as it passes signal well and cleanly and the input and output controls work as they should, however, it won't calibrate and does not show any sign of compressing on the meter.  The meter moves with signal content (1kHz signal as required for calibration)

I have the voltages at each transistor reading as they should, and I can't understand for the life of me why it won't calibrate.  The wiring is correct, as I stated previously and the only pot on the board that seems to work is the tracking pot but only for GR metering but it won't go to 0vu.

Thanks in advance for anyone who has a suggestion.

Carl

 

 

[W DeMarco]

REPOST

OK Ive gone through all of my interconnects which look fine, and my unit is grounded as follows.  IEC ground to chassis, pin one of XLR input to chassis(These two grounds connect too the same point next to tranx about 8 inches from the XLR), center tap straight to pcb.
I am using a mnats board and made use of the G(ground) pad on the main pcb as documented in his wiring guide.  I am still getting a horrible buzz.  My main voltages are fine(30, -10).  Again this buzz gets louder as I turn up the output pot but in the center of travel it all but goes away then continues to get louder as I pass center.  The input pot affects this buzz slightley. 

Also noticing the release is affecting the meter in GR mode with no signal injected.  As you turn it CW the needle travels to the right many Db.  I've read thru this thread twice now but have not been able to find a solution. 

Any help is greatly appreciated!

Will

 

[Chrome Heart]

One thing I still couldn't figure out though...The 6 position lorlin..Why 6 positions where only 4 ratio settings are present? Am I missing anything?

You can move the stop under the nut and set it to 4 positions.

 

[emreyazgin]

One thing I still couldn't figure out though...The 6 position lorlin..Why 6 positions where only 4 ratio settings are present? Am I missing anything?

You can move the stop under the nut and set it to 4 positions.

Thanks, learnt one more thing !

 

[gswan]

REPOST

OK Ive gone through all of my interconnects which look fine, and my unit is grounded as follows.  IEC ground to chassis, pin one of XLR input to chassis(These two grounds connect too the same point next to tranx about 8 inches from the XLR), center tap straight to pcb.
I am using a mnats board and made use of the G(ground) pad on the main pcb as documented in his wiring guide.  I am still getting a horrible buzz.  My main voltages are fine(30, -10).  Again this buzz gets louder as I turn up the output pot but in the center of travel it all but goes away then continues to get louder as I pass center.  The input pot affects this buzz slightley. 

Also noticing the release is affecting the meter in GR mode with no signal injected.  As you turn it CW the needle travels to the right many Db.  I've read thru this thread twice now but have not been able to find a solution. 

Any help is greatly appreciated!

Will

Have you performed all the setup tests and calibration?

Is it a transformer input or active input version?
What is it attached to (input and output)?

 

[a2d]

Hey Will

I had the same problem with mine, the funny thing is that I purchased a new J board, transfered all the parts, rewired and all is good now,( maybe a PCB issue, I'm not too sure, but thats what I'm thinking )
Pine also did the same problem, replaced his main PCB and it fixed it aswell.

Mike

I still have one last issue to work out.- my attack seems like its not doing much.

REPOST

OK Ive gone through all of my interconnects which look fine, and my unit is grounded as follows.  IEC ground to chassis, pin one of XLR input to chassis(These two grounds connect too the same point next to tranx about 8 inches from the XLR), center tap straight to pcb.
I am using a mnats board and made use of the G(ground) pad on the main pcb as documented in his wiring guide.  I am still getting a horrible buzz.  My main voltages are fine(30, -10).  Again this buzz gets louder as I turn up the output pot but in the center of travel it all but goes away then continues to get louder as I pass center.  The input pot affects this buzz slightley.  

Also noticing the release is affecting the meter in GR mode with no signal injected.  As you turn it CW the needle travels to the right many Db.  I've read thru this thread twice now but have not been able to find a solution.  

Any help is greatly appreciated!

Will

 

[cadsound]

I've already checked that, but I just rechecked again, and it's in I'm using the right Pad 18.
I did find an older post stating that if you use the 2N5457 FET, they would have to be inserted in reverse of the board symbols, so I did that (reversed the FETs) and now I can calibrate it to the point of adjusting the GR tracking, but it's not compressing or reducing the gain.  This is my first 1176 build, and though I'm experienced in DIY, I'm a little overwhelmed trying to figure this one out.

Hey Caral,,

check pad 18 there are 2 spots make sure its connected to the wiper of the bias trim pot.

Hi,
I've just finished building an 1176LN REV J MNATS Board using Hairball Audio's Kit.  I have also followed the Rev F-J BOM and Schematic.

I very confident that I've wired it correctly, as it passes signal well and cleanly and the input and output controls work as they should, however, it won't calibrate and does not show any sign of compressing on the meter.  The meter moves with signal content (1kHz signal as required for calibration)

I have the voltages at each transistor reading as they should, and I can't understand for the life of me why it won't calibrate.  The wiring is correct, as I stated previously and the only pot on the board that seems to work is the tracking pot but only for GR metering but it won't go to 0vu.

Thanks in advance for anyone who has a suggestion.

Carl

 

 

[user 37518]

sup guys, i was checking out the other day this webpage http://dsaudio.secure2cart.com/products/ds-solid-176--fet-limiter-compressor.html which im almost sure those guys are ripping off gyrafs designs and selling making a profit out of them, because they both have the same options (like the ne5532 input or trannie), etc...., also it draw my attention almost everything they sell is available here as a DIY project

 

[W DeMarco]

OMG Good find...Almost 1200 bucks without the output Iron.  What a shame.  They also have a dual fet comp as well as a dual pultec style that looks pretty damn familiar.

 

[W DeMarco]

Gswan and A2D,

Thanks much...

So its funny you said that A2D,  I had an extra set of PCBs as well that was mostly populated so I stuffed the rest of the main and slapped it in to no avail.  I did need to pull several bc107s from the original board but that was all I reused.  After that didnt work I built up the ratio switch and put that in with all new wiring.  No luck there either.  

GSwan:  Its electronical balanced,  I did calibrate and it acted fine outside of the big ole buzzy.  I find the buzz when nothing is on input or with a signal generator from a small shure stereo field pre with sine wave.  Output is going to a small mixer, balanced ins.  

Another note, I was hoping to track down the buzz with my scope which Im very undereducated in using.  Without any sine wave, just cranked full with nothing in or out I can see the buzz at the output xlr.  I dont see the buzz at the input xlr or the input pot or the output pot.  These were places where I could easily find the sine wave when I was probing.  Im just a little worried about probing any farther on the PCB.  Ive tried just about everything at this point with my grounding.  At this point the in XLR pin 1 connects to the chassis at the xlr itself and the iec connects to the chassis at the Pwr tranx.  I did try connecting both at the xlr with no change.  I also went through all of my solder points on the main and found no bridges or unsoldered parts.  


I am thinking it must be somewhere after the output pot but havent found it yet.  

Thanks again

Will

 

[mnats]

OK Ive gone through all of my interconnects which look fine, and my unit is grounded as follows...

Just curious as I did not see a description in your post: How is the main board ground connected to the chassis ground?