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

[benlindell]

Here's the results I got from playing with C9 today: you can see that the value of C9 is definitely playing a part in this.

I also listened quickly to music through it after each test and it doesn't seem to have an obvious effect on the sound quality.

 

[stitch-o]

Hi guys,
I quick one (I hope) for someone.
I am trying to figure out proper mains on/off wiring using Hairball pushbutton.
I followed the hairball directions to the T, or so I thought, but what happens is:
when "off" button is pushed in, power on. When other buttons selected, power off.
I'm sure its easy for someone....not for me, right now before coffee.

Any suggestions: mucho appreciation.


Cheers!

 

[benlindell]

Easy, switch the power wires to the other set of pins, the front (nearest the button) and the middle. You want the unit to have power when the button isn't pressed in.

 

[stitch-o]

Easy, switch the power wires to the other set of pins, the front (nearest the button) and the middle. You want the unit to have power when the button isn't pressed in.

Thanks man!
Ok, I THOUGHT that was how I had it.
Here's a pic of my wiring...

Disclaimer: I am out of coffee and my brain won't turn on.
I'm off to the grocery store.

 

[benlindell]

It looks right, I'm not sure if it's the jumpers for lamp power, I took my lamp power from the terminal block where the power comes into the pcb

 

[mnats]

Here's the results I got from playing with C9 today: you can see that the value of C9 is definitely playing a part in this.

I also listened quickly to music through it after each test and it doesn't seem to have an obvious effect on the sound quality.

As the original value isn't shown, does this information contradict your earlier post?

I just tried out a 10uf cap in C9 and I'm still getting the same results if not possibly worse.

 

[benlindell]

Sorry I forgot to include a shot of the 47uf. But it is better
than the 100uf and worse than the 1uf or no cap. I'm nit at ny
test rig so i can't get that up at the moment.

 

[stitch-o]

It looks right, I'm not sure if it's the jumpers for lamp power, I took my lamp power from the terminal block where the power comes into the pcb

Could it be I have the pushbuttons upside down and am switch power with a GR switch?

EDIT: hahaha....uh, yeah. This looks to be the issue....


EDIT2: or maybe not: the hairball PCB for GR meter switching only hits 3 of the four
pushbuttons. I have mine on the top three switches and the bottom switch is isolated for power only...
Strange.

 

[phatmateo]

when "off" button is pushed in, power on. When other buttons selected, power off.

I don't have my 1176 in front of me, but it would seem that you need to trace your connections on your pcb to make sure its breaking the connection when "off" is pressed in(with NO Power Connected of course).  Do you have a continuity function on your multimeter?  This always helps me so much if I haven't had enough coffee   It might be those jumpers, because its obviously working the opposite of what you want it to do.  I got my power from my transformer secondaries so I never had to deal with the pcb.  Remove those jumpers and see what happens or get us a better picture of how its connected.  Good luck

 

[stitch-o]

when "off" button is pushed in, power on. When other buttons selected, power off.

I don't have my 1176 in front of me, but it would seem that you need to trace your connections on your pcb to make sure its breaking the connection when "off" is pressed in(with NO Power Connected of course).  Do you have a continuity function on your multimeter?  This always helps me so much if I haven't had enough coffee  It might be those jumpers, because its obviously working the opposite of what you want it to do.  I got my power from my transformer secondaries so I never had to deal with the pcb.  Remove those jumpers and see what happens or get us a better picture of how its connected.  Good luck

Thanks for the reply!
Yes, I've been 'beeping' through the whole switch and mains wiring.
Triple checked I have proper primary strapped (hairball toroidal for 115 - brown/grey to switch/fuse, blue/violet to neutral on IEC.)
Tho I did read somewhere from Mike that says these toroidals are labeled wrong (????).
Its now officially starting to drive me nuts.
When switch is depressed (on) I get 116 VAC back at
the PTs primary, just the way its supposed to but no power lamp.
Depress in (off), the friggin lamp goes on.
BUT I don't get any DC on the Secondaries.

Im digging around now...

Edit: duh. The 120VAC lamp is completing the circuit when the switch is disengaged.
I need to wire it in series, not parallel. Problem 1 fixed.

 

[phatmateo]

I'm confused why you mentioned DC.  Which lamp are you speaking of?  The red LED above the meter bulb?  If so, does your meter light work properly?  How is your LED connected?  Where are you pulling your DC voltage from?  The jumpers have to be wrong.  Take more pictures if you can
When did you buy your toroid from mike?  The mislabeled ones were in his first batch, I think.  That was a long time ago. Otherwise, it seems like it should be correct from how you said its configured.  You should ask mike if in doubt

 

[stitch-o]

Ok, stupid mistake. As noted above.
When I pull the lamp out of circuit entirely, I get 115 at the primary
but, when I measure the secondaries (DC?) I get next to no voltage whatsoever.

EDIT: I think this was my second problem. The secondaries of the PT are AC (?)
I am assuming, because when I test VAC at the secondaries at the board, I get
29vac and 29vac (1 test lead to black or yellow, one to the center strapped red and orange.
This is correct?

 

[Biasrocks]

29vac and 29vac (1 test lead to black or yellow, one to the center strapped red and orange.
This is correct?

Yes, all your transformer leads will be AC, you won't get DC until after the rectifier. 29vac sounds like it's in the proper range.

I think there's test points provided near the regulators if you want to check your DC voltages.

Mark

 

[stitch-o]

Thanks Bias!
So, I wound up disconnecting the 120vac lamp entirely.
I wired up the VUs festoon lamp instead as it is bright enough to light the
power lamp next to it as well.
Now: when on, I hit the GR button=VU nothing. I hit the +8 button=VU starts dancing.
I hit the +4 button=VU starts really dancing.

I used Stereokillahs original wiring scheme that proved to be wrong, but
yesterday I started sorting it out from the hairball instructions and
Skylars REV D.

Suggestions and pointers welcome, but not expected.

Cheers!

 

[phatmateo]

you are using a dropping resistor for the 120vac lamp, correct?  You should study up on what exactly transformers do in the meta.  There will never be DC coming from a transformer(they actually block it).  Sorry, but you confused me on this!  You have to rectify(smooth) out the AC signal to be a particular voltage in DC.  All of this is done in the power supply section of the pcb.  Calibrate your unit so that your meter works correctly.  Consult the mnats vids!  The dancing on +8 and +4 tells us nothing other than its receiving signal.  Study up on transformers and DC conversion in power supplies please!  Check the meta!  Good luck

oh, and if anyone has hooked up the LED on the front panel, where is a good spot to recommend to tap into some DC for it?  I haven't done it so I wont be any help.  

 

[stitch-o]

 

[stitch-o]

Ok, power sorted.
I plugged the sucker into protools:
No signal getting through whatsoever, just a "whump, whump, whump" LF oscillation.
I just triple checked wiring to all the frontpanel pots - they look a'ight.
But, when monitoring the "thump" the input and output pots do nothing to the output level
or change the thump in anyway.
I'll check voltages throughout after this session coming in but if anyone
has any suggestions as to where to look first, I'd be much obliged.

Cheers from the idiot.

 

[bdubya]

Signal goes from xlr to input attenuator, to input transformer, to the main board.  I'm no whizkid, so I may be wrong, but try looking at your signal  just before it hits the main board, with the input attenuator fully clockwise and not attenuating the signal.  That'll tell you if your fault lies in the xlr input, attenuator, or input transformer (if NO signal is present) or further on in the main board (if you have good, undistorted signal just before the main board).  Check your grounding on pins 1 of your XLRs, I seem to recall having a similar oscillation which was caused by my neglecting to ground pin 1 on my output xlr, no effect upon the signal with either input or output adjustment makes me lean towards the pre-main-pcb portion of the circuit containing the fault.  Hopefully that's some sort of help.  good luck!

ben

 

[Rob Flinn]

I suspect if it's going "whump, whump, whump" then you have messed up something on the board, check for poor soldering, & bridges, & the correct component values.

 

[stitch-o]

Thanks guys:
I'm about to power up the scope now...

EDIT
First issue - input signal: the scope is telling me that the input signal to the input xfmr is good.
Also telling me output signal of the input xfmr is wonky. I had bad solder points at input.
Fixed!

Now onto the thumping...I think I might have a short on one of the transistors maybe...

Second issue - I went through and found a short under the board on one of the transistor pads.
In flipping the board over, I disconnected 16, 15 and 17 (output pot). I reattached 16 and 15 - no thump.
17 attached - thump...AT FIRST...
I disconnected for a minute and, for larfs, reattached: NO thump. Everything works for a minute.
Power off, thump comes back on power up. DEF something with '17' and the output pot.
I'm finished for today but this looks promising.

Thanks all!


Day2: first thing I found - the attack pot (grn) connection on the pushbutton ratio PCB
[as labeled on the hairball ratio instructions] is hanging.
I think I ordered the wrong 25K pot as well (mine is SPST) so, for now, I will wire permanently on til I can
order a new  correct pot (mouser: 315-2415F-25K) and figure out the thump issue.

So a brief conversation in the G1176 build thread with GSwan has led me to a strange place:
He says that if '17' is hanging, there should be no audio passing whatsoever....
Can anyone confirm that the diagram (skylar's rev D?) below is THE correct wiring scheme?:::

I have followed it almost exactly and need to figure out if my problem is somewhere else.

Further tests reveal: with all connections except power, input and output connected, I still
have signal passing to output. I think there is something wrong (blown transistor, wrong part, etc.) on the board as I
shouldn't be getting any audio with the output pot disconnected...

One thing I noticed in re-reading all the info:
"To make the 1176 limiting amplifier, however, just replace Cx6 with a wire link and leave Rx14 off the Signal Line Amp board."
I have these parts installed so I will try and remove them as per the above instructions from MNATS.
-removed- unit still passes signal with output pot disconnected...

I'm still baffled as to why, with all the external wires and output pot not connected, I'm still getting signal!
Wouldn't this suggest a short somewhere as opposed to a wrong component?
I am leaning towards this as the problem.

Day three: so I'm going through and buzzing continuity through the signal circuit vs schematic.
First thing I notice is on the schematic, C7 is 1uf with polarity. The build and spacing on the board
is for a non-polarized cap. Does this make a difference? I don't think its related to my issue, but it was kinda weird.

Some voltage tests indicate:
CR6 @ -9.8
R87 @ 24.1

28 and 28 VAC at the PT sec @ the board.
These look ok...

q2   3.5
q3   5.8
q4
q5
q6
q7  11.4


Ok, My idiocy has started revealing itself:::
Dustin (of Regular John Recordings - THANKS Dustin!) has noticed that I had my trim pots in wrong.
They were perpendicular to the correct orientation. D'OH!
Changing these had a HUGE effect on my issue of passing audio while output pot/'17' is disconnected (which I am convinced is the source of my issues). There is no Oscillation anymore and the signal passing is MINIMAL as opposed to where it was before, even with input at full clockwise. BUT I think there is still one short as there is still that freakin' tone (as quiet as it is) being passed to output.
Almost there......

Edit:
The thing WORKS! Flipped the trimpot orientation, wired everything back together and BLAMO! the sucker is squashin'.
Of course the first thing to try was a snare. Oh, Im going to DIG this box!
So, I need to get a new meter as I think I fried mine with my original, stupid mains wiring.
Once I get that hairball order straightened out, I can calibrate properly and off we go.
...I hope...

Mike from Hairball, Gswan, Mr. Flinn, others and especially DUSTIN FROM REGULAR JOHN RECORDING!!! You guys are friggin' awesome.
Dustin, seriously dood, I owe you a keg'o'beer.