"May I?" distortion pedal based upon ROG MayQueen

[alex frias]

Nice to know somebody else built and liked it.

Well, it's working. It's hard to be cathegoric about accomplishment or completion of the project. Anytime, soon or in distant future, it can be modified and getting better, all the time.

It's up to you to decide when you find the right time to build it up.

On the other hand, with other people building it, that could generate new pathes for the evolution of the project.

I'm not offering a complete commercial project for the one's pleasure, it's just something I'm sharing with all you people, whose shared wonderfull stuff for a long time.

[gigimarga]

I forgot something: i added a 1K resitor in series with the "Drive" pot (without it i have no sound with the Drive at minimum)!

[alex frias]

Very smart!!! I think you put such thing between the 9 volts and the lug that was connected to the 9 volts before.

[Bucksears]

Well, it's working. It's hard to be cathegoric about accomplishment or completion of the project. Anytime, soon or in distant future, it can be modified and getting better, all the time.

It's up to you to decide when you find the right time to build it up.

I guess I should clarify; I just meant is there a version that has most of the bugs (if any) worked out. i.e. most current version of the schematic.

Thanks again for this great contribution!
- Buck

[alex frias]

OK, no worry!

I think this version with brazilian guy (o Grande Güero) layout is pretty safe.

[gigimarga]

I think you put such thing between the 9 volts and the lug that was connected to the 9 volts before.

Yes, you're right!

[alex frias]

I just tested it , still an unboxed arachnoid, in a very radio frequency affected place and the noise floor went up with new high frequency elements. So I put a very small cap (about 27pF) in front of the first stage, between the signal path and ground, and the things calm down.

Gigimarga,

Any pictures or/and new commentaries?

[gigimarga]

No news...still unboxed and i had a lot of work at my job, so no time for DIY

[nickbungus]

Please HELP??

From the video I think the May I sounds amazing, so I decided to build one after successfully building the May Queen.

I have built it by etching a PCB from Gueros document (www.handmades.com.br), which can be viewed here: http://www.dirtmonkey.org/MayI.pdf .

Problem is, being a newbie, I cant get it to work.  

After some googling I found this article: http://www.diystompboxes.com/pedals/debug.html.  And I built the probe as recommnded.

The probe works great but I can only trace the circuit as the far as the first legs of C1 or R1.  The signal goes dead after that.  I first replaced and re-tested C1 and R1 and they seem fine.

I used an AC176 as the germanium tranny, but this was the most confusing part of the build.  I take it, on the PCB layout going down the pin layout is ECB?  This also meant I had to manipulate the pins.

Although I am trying to learn, I don't understand the circuit exactly.  Would it be correct to say that I have wired Q1 incorrectly?  Or could the problem be the diode?

Any help is more than welcome and if I am lacking in info then please let me know.

Kind Regards

[bluebunny]

If you have signal only up to the C1/R1 junction, but not beyond, then perhaps your C1 is toast.  Check out the sticky "DEBUGGING" thread at the top of this forum.  It will take you through all the steps you (and we) need to debug your silence.  We'll get it sorted!  Pictures help too.  BTW, Google should help with AC176 vs. OC140 pinouts.

[nickbungus]

Thanks BlueBunny.  Everyone on here is so helpful.

That's exactly what I first thought.  So I took C1 out and tested it on my multimeter with the capacitor setting and it seemed fine.  I then found and replacement, tested that and refitted.  With the same result.

I did take some time and effort figuring out which pins were which with good old Google.  This was what I found http://www.dirtmonkey.org/AC176.png.

I may have still got it wrong though.  I'm just stuck as to where to go next.

Thanks

[bluebunny]

THIS   

[nickbungus]

Thanks.  When I get in from work I'll go through it to the letter. 

[stallik]

Nice, very nice! Wonder how I missed this one?

[GGBB]

I take it, on the PCB layout going down the pin layout is ECB?

Yes - that's correct.  I'm not sure why that was done as it looks like it would not have taken much effort to rearrange the layout so the pinout was C-B-E top to bottom (which matches the spec sheet I found for the OC140).

[nickbungus]

Thanks GGBB again!

In response to BlueBunny:

1.  What does it sound like?
I'm getting no recognisable output although its a bit noisy - when I adjust the pots I can here the relevant change to the white noise (i.e adjusting the treble makes the noise more trebley).

2.  The circuit is The May I by Alex Frias
3.  The source circuit I have put up on my web http://dirtmonkey.org/MayI.pdf
4.  The only modification I have made is to run wires from the circuit to a bit of veroboard for the trim pots.  I did this because I enlarged the etched PCB to make soldering easier (sorry, newbie).
5.  The only part I substituted was to change the OC140 tranny to an AC176.  This was suggested as a suitable replacement
6.  There is no positive ground to negative ground conversation
7.  My battery directly gave me 9.35v

Q1.  E = 2.45v   C = 2.6v    B = 2.46v
Q2.  E = 0.1mV  B = 0.65v  C=  0.72v
Q3.  D = 0.72v  S = 1.85v   G = 7v
Q4.  D = 2.36v  S = 0.7v  g = 0v

D1.  A = 2.45v  C = 2.45v
D2.  A = 0v   C = 9v

I hope this helps.  I also checked the voltage at the other end of C1 where the sound goes dead on my probe (http://www.diystompboxes.com/pedals/debug.html).  I was getting 2.45v which seems to be a magic number as far Q1 is concerned.

Thanks

[bluebunny]

Not sure what you mean by "magic number"!  Looks like Q1 E and B are the same to my uneducated eye.  Perhaps you may have fried D1 and turned it into a short?  Ge is a little less forgiving of, um, over-enthusiastic soldering.      And I would expect the trimmers to have been set so that the JFET drains were around half the supply, so about 4.5V.  If Q3 D is really that low, not much (full-wave) signal is going to get past it.  (And Q3 S being higher than D makes no sense at all!)

Have a tweak of those trimmers.  And see if you can check the roadworthyness of D1.

[nickbungus]

Thanks BlueBunny

Perhaps I mean more of a tragic number as it seems to be the voltage of all components and pins around Q1, which I presume is not desired.

Not to worry though as I bought a few D1s (1N34A).  I used a heatsink on all transistors but not my Diodes (lesson learned).  I will firstly redo/check D1.  Over-enthusiastic soldering has certainly been going on.    When I desolder D1 and test it, what tests are recommended?

I will also double check my readings of Q3, perhaps I got the pins wrong?   I also haven't played with the trimmers to a great length, all I have done is some 'jazz-testing' as we call in software development, to see if I can get some sort of true signal.

GGBB and BlueBunny, I have never ever encountered a community where newcomers are so tolerated and helped.  Amazing.

[bluebunny]

Diode: put your meter on continuity setting.  It will bleep in one direction, but not in the other [good].  If you fried it and fused it into a short circuit, it will bleep in both directions [bad].

Trimmers: measure the voltage at the JFET drain and adjust the adjacent trimmer until this value is around 4.5V.  Repeat for the other JFET.

Merry Christmas.   

[nickbungus]

Thanks BlueBunny.  Hope you had a great Christmas too.

I decided to create the veroboard version over Christmas and its all working - yay!

Thanks so much for your help.  I will now go back to the PCB version and see if I can get the thing working with your recommendations.

Thanks again.