All things G1176 - the new "repost" thread.

[aclac]

To be honest I'm not entirely sure what fixed what.  I pretty much just redid the wiring and solved a bunch of issues.  Pad 23 on the board wasn't connected to ground, so I'm guessing that was part of it

HEY, must ask... Where is that pad 23 (which board/ver. you have)? Aclac

 

[aclac]

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

HUH... I hope, that your diagnose is wrong a2d, because I has 2 mnat's brand new unit (ver J) and same problems (ratio pot effect -20 dB VU drop without input- signal) and some strange hum, if XLR- input connector is free. (These units has lots of soldering and...). Btw. I noticed that my hum problem is more painful, when input and output pots are full position. But I noticed same time, that this little thing has so huge amplification in "full gas", that I never can't use it like this. Okay, I have readed lots of post's here and decided that first I have to change input tranny (OEP) ratio from 1:1 to 2:1, it is more flexible to use and... I think that this can drop also my little "hum problem". Secondly I hope that my calibration process has made wrong somehow and I re- calibrate those units in the weekend after input tranny- mod and hope that this solve ratiopot/VU- problem. Anyway... this G1176 sounds so nice and compress is so smooth, that I coudn't belive at beginning... Aclac (sorry my bad english)

 

[leadbreath]

Hi Guys

As its my first question on this forum id just like to take this oppurtunity to thank eveyone for contributing to this site, its quite an inspiring place.

Right, now that formalities are out the way, ive just finished wiring up my mnats j board and checked the power supplies and get -9.7 and + 28.3. I checked thru this thread and i saw that its critical to get +30 on the pos. side? When installing R87 i measured it on my DMM and noticed that it was only 1090 ohm, this was the best i could get out of a whole bunch of 1.1k's. I then changed R89 to a 270 ohm and i now get bang on 30v. So i was happy clappy and installed all transistors and fired it up and smoked my one and only BD517(Q8)???

Could this be cause changing R89 is sending too much current to Q8??
I double checked all components/polarities and all ok?
Ive also checked for blatant shorts and all seems fine?

If anyone out there can give me any advice it would be greatly appreciated.
mick

 

[mac]

Hey Mick,
can you give us a summary of your voltages at Q8?

Mac

 

[mnats]

So i was happy clappy and installed all transistors and fired it up and smoked my one and only BD517(Q8)???

Did you carefully check the pinout of the transistor and use the alternate pads mentioned here and here?

 

[leadbreath]

hi guys

thanks for the speedy replies.

mac, voltages on Q8 as follows:
E = 4.5v
B = 28.1V
C = 30.1V

mnats, i definitley used the alternate pins and the orientation of the transistor was right, as it was my only one i made sure i didnt f@*£ it up...

i noticed voltage past R17 is 28V not 25.8 like in the schemo??
R17 measures ok.

so i take it changing R89 from 220 TO 270 Ohm is ok then???

 

[milosh]

Hi All !!

This is my very first post here  ;D
I am starting to build my 1176 clone. This is my first DIY electronic project so please keep thumbs up for me
I am collecting all the parts at the moment.
My first question is:
Did anybody tried to use BAV21 diode instead of FDH333 low leakage diode?
It is hard to buy FDH333 at my location (Poland).
I found somewhere BAV21 could be a good replacement. Could it be truth?  ???

cheers

milosh

 

[gswan]

Read the data sheet. The FDH333 has a reverse leakge current of 3nA. The BAV21 has a reverse leakage current of 100nA, so for a low leakage diode replacement it is 30 times worse. You could try it, but ir may not work properly for long attack/release times.

 

[milosh]

thanks gswan

It seems I will have to get FDH333 diodes some way

 

[gswan]

It's probably best, however if you have a couple of BAV21's handy and want to do some testing (provided you also have some test gear to do the testing) ...

 

[barclaycon]

Milosh.
I bought a bulk pack of FDH333 diodes a while ago
PM me your address and I will send you a couple.

 

[milosh]

thanks barclaycon !!

That is nice to meet so friendly people here
I've just PM'd you

I can say I love this forum since my first post

cheers

milosh

 

[milosh]

I want to build 2 G1176 in one box.
I would like to use 1 PSU board from mnats to feed them.
My question is about power supply transformer.
Part list on Gyraf's site says 2X24V/500mA transformer for single unit.
Do I need to use 1A transformer for double unit?
I found 2x24V-2x0.72A at local electronic shop will this be good for 2-G1176?

Sorry for such a lame question  :

cheers

milosh

 

[milosh]

Ok I found the thread "MNats PSU/ Twin 1176 Power Transformer"

 

[JW]

Hey guys,

I've been using my G1176 for awhile now. Sounds great on anything without fast transients. I'm noticing, though, that with drums, the fast transients seem to be causing a nasty peaky distortion.

Any idea what could be causing this?

I built a dual channel unit. Both channels react the same. I've calibrated both a number of times according to the instructions, and thought I finally got it until I heard this problem.

 

[SWAN808]

I have a 1176 build Im getting some help with at the moment. My question is - do most people wire in a hard bypass so that there can be a proper comparison with the original and compressed/level balanced signal? I assume the 'meter' bypass is not that great for comparisons? My 1176 is stereo also.

 

[claudio.accatino]

Hi everyone,

I've just finished assembling my very first 1176 Rev.J using a MNATS board and Cinemag O/P trafo.
I'm a complete newbie in DIY, so I bought a kit of parts, case, trasnsistor, trafo, etc. plus instructions from a local italian dealer who sells MNATS boards too (shame on me!).
Being a newbie, I didn't check all the component values before assembling the board with components and I trusted the labels put by the reseller.
I followed the instructions and the labels and I completed the board and the whole unit.
Without the ICs in their sockets I measured correct "first check" voltage values (+30 and -10).
Then I placed the ICs in their sockets (following the paper labels made by the seller).
I checked the previous values again and they do not match anymore. No smoke, no bad smells.
Looking at the schematic on MNATS site, I soonly found out that the TL071 and the NE5532 were inverted (shame on me again!) and I learnt not to trust paper labels anymore.

I replaced the ICs with new (and correct) ones, I checked for bad solder joints but everything seemed to be OK. I measured correct values again (+30 and -10).
I followed calibration instructions measuring levels with a NTI Minilyzer.
I had some issues calibrating amplitude levels between the meter and the Minilyzer but I decided not to concentrate on this since I measured correct values regarding compression and I finished calibrating the other trimmers.
I started testing the unit with music.
Everything seems to be ok soundwise. Attack and release are working as they should, I can hear a true FET compression (I've used a real 1176 several times). The actual sound it's pretty good.
Problem is, I'm having some strange behaviour on the input stage.
Briefly, it seems that the input is about 10 dB more sensitive than I remember, as the unit starts compressing way too early (referring to knob position) compared to the silverface one I used often in the last few years. I admit that I haven't been able to A/B them yet.
I decided to check again for component mismatching using Gyraf schematic and BOM as reference.
I checked all resistor colors and I found out that R33 is a 4K3 instead of an 11K (I'll never buy again from this dealer!!! ).
I also measured all the voltages mentioned in Gyraf schematic and I don't see any serious deviation from written values.

In the meantime, I discovered this board and I started reading some of your discussions.
Any help from board members is appreciated.

Is this input sensitibity a "common" behaviour in Rev J clones?
Is it possible that I damaged some components during IC mismatching?
Is it possible that R33 is causing the sensitivity problem (though it is not in the input stage judging from the schematic)?

If needed I can attach/send the voltages I measured compared to the ones in the schematic and/or explain more in detail calibration and measurement procedures.

Thanks!!!

 

[mihailojocic]

Hello,

after successful build of G9 I decide to build G1176 also. I have problem to find BD518 and BF245. Can I use 2N5457, 2N6728 and 2N6716 without any change to the board?

Thanks!

 

[Chrome Heart]

Hello,

after successful build of G9 I decide to build G1176 also. I have problem to find BD518 and BF245. Can I use 2N5457, 2N6728 and 2N6716 without any change to the board?

Thanks!

You can use the 2N5457 on the Rev. J board but you have to turn them around. The pins are reversed.

 

[mihailojocic]

Thanks Chrome Heart,

it means lot to me. I believe that replacement for BD517/518 is BD139/140 so my problem is mostly solved. Just one big order from farnell and Canford. 

I found FDH333 on Farnell if someone need it.