[BUILD] 1176LN Rev D DIY

[thesystem]

Here's some pictures:

 

[jplebre]

Sorry I meant the cables at the far left, the meter section. That whole drive section is for GR metering.

The callibration procedure gives me no problems. I'll check my cabling and the voltages again and report back

Including the last step? if the GR meter goes up, you would never be able to match the -10dB gain reduction and o/p. I'm sure I'm misunderstanding you somewhere :S

Don't have schems on me right now will try and look through your pics later.

As for the fuse:

Quote from: john12ax7 on July 24, 2012, 02:09:29 AM
Quote from: Echo North on July 24, 2012, 02:02:42 AM
You using a slow-blow?  It's gotta be a slow blow.

Yes, the 250mA SB blew once, so not sure if it was just a random occorence. Gonna buy some more but right now have a 500mA SB with no issues. But with a 30VA transformer a 250mA seems more appropriate.

If you just blew one 250mA slow blow, that can happen.  If you keep blowing them you might have an issue.

 

[thesystem]

The callibration procedure gives me no problems. I'll check my cabling and the voltages again and report back

Including the last step? if the GR meter goes up, you would never be able to match the -10dB gain reduction and o/p. I'm sure I'm misunderstanding you somewhere :S

When doing the last step of the calibration the drop of -10 dB is happening just as it should. I experimented a bit more with the compression today and it seems that the metering shows the right amount of GR in GR mode when OP pot is all the way down. It's also showing the right values when I turn the OP pot up untill the bypassed signal is about equally loud as when the compressor is active. But when I turn the OP pot further up so it will be louder than the original signal, the meter starts going both ways. First it shows 'less compression' (which is actually not really happening) on the meter and when turned all the way up it will move up and down as if combining +4 metering and compression metering.
Hope my explanation is a bit clear, sorry if I'm not explaining that well!

 

[jplebre]

I think you might have a short somewhere. Check the meter board first.
Careful with the 240vac

If you find you have to redo the connections, it is a good idea to install molex connectors. Connectors are cheap and the tool is a good investment (if you plan on doing more DIY or repairs you'll be using it quite a lot as molex is a great way to test swap etc.)

I'll still try to look at your wiring at home :S

 

[thesystem]

OK, thanks for the advice. On my first build I actually used Molex connectors but I don't have them in stock any more. Have to look for a place to get them. Does Mouser have these? I couldn't find the right ones there.

Besides a visual check, how do I check for shorts with a MM on the meter board? Sorry for these questions..

 

[jplebre]

Mouser does, are you in the EU or US? UK rapid online and farnell have them too.

 

[thesystem]

I think I found the problem! The orange wire on the meter board was shorting the blue wire. Fixed it and now it's working perfectly!
Thanks for your help jplebre!

I'm in the EU btw.

 

[jplebre]

if you are in the eu have a look to Rapidelectronics, farnell and RS. They are nice providers.

Cheers
J

 

[braeden]

Well, I re-calibrated my 1176, I made sure that I was getting 0.775Vac at the input @ 1kHz.

I still can't get it to compress normally, the only time I see any sort of compression is flicking the switch between stereo link and normal mono operation.
The needle jumps to the left on the VU meter and responds to attack/release and ratio settings when switching to stereo link.

Has anyone else had this problem? I don't believe there is a short anywhere :-\

Thanks!

 

[jplebre]

I haven't really looked at stereo link much or rotary version (which you said you had on a previous post).
I saw that you followed the rotary switch pages on Mnats, did you see this document as well http://hairballaudio.com/guides/Stereo_Link_Wiring_Guide.pdf

 

[Echo North]

Well, I re-calibrated my 1176, I made sure that I was getting 0.775Vac at the input @ 1kHz.

I still can't get it to compress normally, the only time I see any sort of compression is flicking the switch between stereo link and normal mono operation.
The needle jumps to the left on the VU meter and responds to attack/release and ratio settings when switching to stereo link.

Has anyone else had this problem? I don't believe there is a short anywhere :-\

Thanks!

Does it work without the stereo link installed? (disconnected, not just off)  I'd be nice to know if the issue was in the compressor or stereo link circuit.

 

[jason baliban]

Hey guys, is this an acceptable replacement?

This...

http://www.digikey.com/product-detail/en/RPE5C2A201J2P1Z03B/490-3636-ND/946272

instead of this...

http://www.mouser.com/Search/ProductDetail.aspx?R=140-50P2-201K-RCvirtualkey21980000virtualkey140-50P2-201K-RC

Thanks so much!

jB

 

[Echo North]

Looks likes a good replacement.

 

[jplebre]

higher voltage replacements are almost always fine.
You will not have a problem with these ones.

 

[jason baliban]

I figured as much, just wanted to make sure.

Thank you,

jB

 

[wlambert]

Last night I managed to finish building and calibrating my Rev D after a few snags!  The unit sounds fantastic!  So happy with it.  Many props to mnats, Hairball, and all the good folks on this forum.  I didn't even have to post my questions because all the answers were in here waiting for me to read them.

I wanted to share a couple things that could be of some use to current and/or future builders that was not totally clear to me when starting...

For my build I used the 2N5088 in all available locations (Q5, Q7, Q8, Q9, Q10, Q12, Q13). Let me tell you, do spend some time checking and double checking and triple checking the pin configuration on these components before you stuff them in the boards! I first mistakenly populated these comments improperly and I spent the better part of 24 hours trying to figure out what was wrong with my build when I powered it up.  Somewhere along the way I was misinformed in either in a post on the forum or I misread somewhere or on the datasheet...  who knows.  Upon start-up, I blew R32, was blowing fuses left and right, I was not reading proper voltages at the test points provided in the PDF on mnats FAQ page, couldn't cal the unit for squat, and some other wackiness.  I had already checked my power supply and it was very stable so I ruled that out early on.  It was looking quite grim for a second but I hung in there had an inclination that there was a somewhat simple solution that would singlehandedly fix many, if not all of these problems, which would eventually be true.  I wondered how so many voltages could be wrong?!  All of my solder joints and wiring was legit... something was wrong!

I read in my research that a common reason for R32 to burn up is incorrect output transformer wiring... this was not true in my case.  It was properly wired via the transformer wire colors, the PCB label, and the mnats instructions.  Ultimately the reason my 1176 was being dragged through hell was because the 5088 were not properly installed.  So, if you're burning R32's and you're using 5088's, check your pinouts! 

The in-line transistor holes for the above listed Q's are for an ECB config and the triangular shape nearest to the left (leaving alone the far right hole) is for an EBC config.

Just to verify for 5088 users, the extra pad on the top of the mounting hole set for each transistor is a redundant base pad for use with an EBC config, like the 5088.  This means you can use this pad in conjunction with the two pads DIRECTLY below it (E and C).  So, you will be mounting the transistor in a triangular shape and will NOT be using the pad farthest to the right (looking down reading from left to right).  I went ahead and tested continuity between the in-line base pad on the far right, and the alternate base pad on top and sure enough they were connected.  After I found this out, the light went off and it all made perfect sense!  I wasn't exactly sure how to seat this transistor in the pads before this since the board wasn't marked (only a graphic shape).  So, if this extra pad wasn't there, one would have to shrink tube the C and B transistor leads and essentially criss-cross them to get them in the proper pads, which would be a pain in the @$$ and if not done properly would cause shorting and I'm sure would start blowing $h!t up.  No good.  So, thank you mnats for this convenience!

After seating these transistors properly my voltages lined up, the machine passed clean audio, compressed, the meter worked, I could cal it, and it sounded amazing!

As of now I've not been blowing fuses anymore... I was originally confused by this because my +30DC and -10DC rails were stable from the start, even with the transistors in wrong.  Perhaps it may start happening again regardless?  I'm not sure at this point.  I'm using 250mA slow blow fuses.  I may switch to 400mA or even 500mA if it starts happening again.  In an earlier post I read that some guys were getting inrush peaks at and above 500mA.  Also, when these fuses blew, I really had no indication they had blown on me.  There was no brief start up and then die off... it was, turn the unit off, ok, good... now turn it back on.... oh... nothing.... weird. 

In retrospect, I'm glad I was forced to work diligently in figuring out my issue and fixing it.  It would have been great to fire the thing up, cal it, and rock and roll right off the bat but that just wasn't the case.  Now I know the circuit way more than I would have and I learned a lot of other things along the way, too.  In a way, I'm glad. 

Word to the wise, pre-measure your components, check check check your transistor pinouts if you're using the 5088's, and DON'T GIVE UP ON YOUR BUILD if you're having issues!  Too much good info on this forum to let your project sit on the shelf.  I'm working on three of these builds right now so I can go ahead and finish the other two for my buddy!  I'm hopeful now that I've been put through the 1176 ringer, finishing these other two will be a snap.  Can't wait to build more in the future!

Wes

 

[Che_Guitarra]

A couple of weeks interstate and now i'm home to finish off my Rev D.

After a small OT wiring hiccup it seems all is well and the unit is stable... time for calibration.  Speaking of which - is there a way to calibrate a 1176 without dedicated tools?  Sending out a 1kHz wave from my DAW is easy enough, but I don't have any equipment (that I know of) to calibrate for a steady 0dBu/0.775 vrms output.  I usually build guitar amps so this type of tweaking is something i've never tried before.

Any tips?

 

[Echo North]

A couple of weeks interstate and now i'm home to finish off my Rev D.

After a small OT wiring hiccup it seems all is well and the unit is stable... time for calibration.  Speaking of which - is there a way to calibrate a 1176 without dedicated tools?  Sending out a 1kHz wave from my DAW is easy enough, but I don't have any equipment (that I know of) to calibrate for a steady 0dBu/0.775 vrms output.  I usually build guitar amps so this type of tweaking is something i've never tried before.

Any tips?

You really just need a DAW and a decent DMM that will read up to 1K.

For setting the qbias try this:

If you have a version with the "off" switch on the attack pot, you can just switch that.  That will ground pad 22.  Feed a 1khz signal into the input at about 0dBu.  You can put your DMM across input xlr pin 2 and 3 and look for 0.775VAC which is about 0dbu.  Your DAW might say it's sending out a -16dBu FS signal or something.  Just do what ever you need to do to get 0.775 VAC across 2 and 3 at the input.

Now put your DMM across pin 2 and 3 on the output xlr and turn the qbias (in and out knob mid way).  You should see the output moving up or down.  Turn the bias until it gets to the max and doesn't get any higher. 

Then adjust the output knob so you see +11dbu (2.75VAC) at the output.  Now pull the qbias back until you get a 1dbu drop 10dbu (2.45VAC).  That will set you bias.

 

[Che_Guitarra]

Thanks Mr Echo 

Trying to get there, but i'm killing fuses at a very fast rate.  All five I received in my latest Mouser order are now cooked... I think a couple were faulty from the get-go, but I have definitely fried the other three at my own hand.  In particular, the fuses seem to 'go' when I use the off button and let the unit sit, rather than turning it off at the wall... something to do with the on/off process... or perhaps the fuses themselves.

Maybe i've ordered the wrong type (125mA slo-blo, apparently, but no way of testing - for 240V operation), but otherwise i'm just not seeing any faults/shorts/cold solders/errand wires to explain it away.

Hmmm....

 

[jplebre]

I'm using these http://uk.mouser.com/Search/ProductDetail.aspx?R=0034.3111virtualkey69300000virtualkey693-0034.3111

a fault when the unit is off can only occur between the IEC lead and the main off switch.
Did you test the switch for continuity making sure it's ok?

Although Mnats does say:

Insert the appropriate 5 x 20 mm fuse in the fuse holder - 1/8 Amp Slo-Blo for 120V or 1/16 Amp Slo-Blo for 240V AC line voltage.