[BUILD] 1176 Rev A - Back to the beginning...

If we're looking at this documentation:

http://mnats.net/files/1176REVA_125_DOCUMENTATION.pdf

Is it not, left to right when viewing the PCB:

Violet
Grey
Black
White/Red
White/Black
Brown

Because that's what I've been using, and she's burning up.  It's what it says, and I can't see how it can be done any other way...?

that document is for the version 1.2.5 boards.

if in doubt, just follow the schematic. For instance, in that document you linked, one side of resistor R32 (the side connected to C13, which should be a 1nF film cap) connects to the pad with the white wire with a red stripe. The other side of R32 (The side connected to ground) connects to the pad with the violet wire.

Find the correct documentation, (mnats' site) then check all wire connections.

edit: I now see in the version 1 schematic posted on the previous page that there was no C13 in that version, but please understand I'm not familiar with the differences between the older versions and the current v1.2.5, so I hope this hasn't caused any confusion!

I have the original printouts here for V1 - same transformer colours and designations.

From the 2008 Rev 1 documents.  Only thing I just noticed is that small ground image - I don't think there's another pad dedicated for that though?

Siegfried Meier said:

From the 2008 Rev 1 documents.  Only thing I just noticed is that small ground image - I don't think there's another pad dedicated for that though?

Click to expand...

The ground pad connects to the neg side of C25.  If it's missing you can just direct connect there.

Other issues could be:

Improper biasing of Q6 (wrong resistor).
Shorted cap around Q6.
Bad Q6.

You're output is pulling way too much current.  You need to inspect the output stage.

Mike

I have a question for everybody:

Is there a minimum or preferred HFE for Q6 (2n3053)?? The Central Semicon 3053's I got from Mouser range from about 112 up to 148, while a pile of new old stock Fairchild's are mostly below 80 hfe, in fact most are between 28 and 50, a few scattered around 100, and with a handful being much higher, between 140 and 168 hfe. It's almost like the Fairchilds were picked through already... however the Cens from Mouser are much tighter specced it would appear!

Does it matter? I'm just matching up pairs for a few stereo sets of Rev A's, measuring hfe with a Peak Atlas DCA55. If I can get away with lower gain, then I have tons of nice matched pairs around 30 or 40 hfe, but if that's too low then I'll just order a bunch more from Mouser. Will it even make a difference?

Just wondering what the effects of different hfe at Q6 will have on the circuit, specifically matching the gain between two stereo-linked units.

Any help, suggestions, or experience is appreciated! Thanks!

edit: note that Central Semi's datasheet on the 2n3053 suggests they can legally range from 25 to 250, so all parts SEEM to be in spec.
http://www.centralsemi.com/leadedpdf/2n3053.pdf

JeroenRoth said:

Hey All,

First of all thank you guys for putting together this nice kit!

Sofar I'm happy with it but I've stumbled across two possible problems. In the following video a demonstration:https://www.youtube.com/watch?v=XUbyS_bPXzQ

And in text:
When I have the compression off and the meter showing gain reduction, the meter will still slightly move if I crank the input. If I go past half on the input with the compression off I get distortion.

Attached is a photo of the wiring.

-Jeroen

Click to expand...

Can anyone tell me if this is normal or not? If not could I maybe get some pointers on how I could fix it?

JeroenRoth said:

Can anyone tell me if this is normal or not? If not could I maybe get some pointers on how I could fix it?

Click to expand...

By the Input/Output settings it looks like you're just overdriving the unit. Remember, at heart this is simply a mic pre with > 40 dB of gain! Switch to +4 meter and I bet it's pegged to the right.

I'm not sure about the wavering GR needle. I haven't seen that behaviour.

Looked everywhere for this one..
Rev A. sounds wonderful, acts like it should.

One issue: Occasionally it will get a fairly loud static sound coming out of it. I smack the faceplate, and it goes away. Typically does it soon after turning on the unit, but occasionally will do it randomly after the  unit has "warmed up." Also, if I bump the rack that the unit mounted in it make a loud "click," and the needle jumps as well (in GR mode.) Any suggestions??

peartplus said:

Looked everywhere for this one..
Rev A. sounds wonderful, acts like it should.

One issue: Occasionally it will get a fairly loud static sound coming out of it. I smack the faceplate, and it goes away. Typically does it soon after turning on the unit, but occasionally will do it randomly after the  unit has "warmed up." Also, if I bump the rack that the unit mounted in it make a loud "click," and the needle jumps as well (in GR mode.) Any suggestions??

Click to expand...

Hmm.... That's a new one for me.

To test for intermittent connections maybe take an insulated probe of some kind, a wooden chopstick i've heard works good, or I use these plastic tweezers I got a set of 5 somewhere, and push on things. Top off, powered on, whatever conditions/settings you had before when the fault appeared, and poke around. Wiggle pots, wires, transistors, componants, looking for lifted traces, bad solder joints, anything like that. That's as good a place as any to start. And of course, as always, be careful in there.

hymentoptera said:

peartplus said:

Looked everywhere for this one..
Rev A. sounds wonderful, acts like it should.

One issue: Occasionally it will get a fairly loud static sound coming out of it. I smack the faceplate, and it goes away. Typically does it soon after turning on the unit, but occasionally will do it randomly after the  unit has "warmed up." Also, if I bump the rack that the unit mounted in it make a loud "click," and the needle jumps as well (in GR mode.) Any suggestions??

Click to expand...

Hmm.... That's a new one for me.

To test for intermittent connections maybe take an insulated probe of some kind, a wooden chopstick i've heard works good, or I use these plastic tweezers I got a set of 5 somewhere, and push on things. Top off, powered on, whatever conditions/settings you had before when the fault appeared, and poke around. Wiggle pots, wires, transistors, componants, looking for lifted traces, bad solder joints, anything like that. That's as good a place as any to start. And of course, as always, be careful in there.

Click to expand...

Thanks! Ill take a poke around and report back any findings.

peartplus said:

Thanks! Ill take a poke around and report back any findings.

Click to expand...

Maybe post a clip of the sounds, or a quick video, if you can. Sometimes a recording is worth a thousand words.

Hard to even guess what's happening without hearing it.

hymentoptera said:

peartplus said:

Thanks! Ill take a poke around and report back any findings.

Click to expand...

Maybe post a clip of the sounds, or a quick video, if you can. Sometimes a recording is worth a thousand words.

Hard to even guess what's happening without hearing it.

Click to expand...

Is your wiring fairly well routed and tidy? Are the ground connections secure with powder cleared?

Mike

hymentoptera said:

peartplus said:

Thanks! Ill take a poke around and report back any findings.

Click to expand...

Maybe post a clip of the sounds, or a quick video, if you can. Sometimes a recording is worth a thousand words.

Hard to even guess what's happening without hearing it.

Click to expand...

I have an audio file of it acting up, but have no idea how to post it here.  If you PM me your email, I can send it to you!

Hairball Audio said:

hymentoptera said:

peartplus said:

Thanks! Ill take a poke around and report back any findings.

Click to expand...

Maybe post a clip of the sounds, or a quick video, if you can. Sometimes a recording is worth a thousand words.

Hard to even guess what's happening without hearing it.

Click to expand...

Is your wiring fairly well routed and tidy? Are the ground connections secure with powder cleared?

Mike

Click to expand...

Hi Mike,
The wires are well routed and fairly tidy.  Powder coat was cleared significantly.

Does anyone have a data sheet for the original DF60214Q  transistor?
TIA

my 1176 units are back home. so i cant measure...
how much current going through attack-release pots. any idea ?
i am looking to use digital pots etc..

thanks,
kambo

I just wanted to tell you guys that my blue stripe is working perfectly and man... it sounds awesome!
I really really dig it on lead vocals....! I don't know why I didn't get one sooner...
I am going to need a few other ones