MXR Distortion + vero build

[LonePhantom]

I decided for my second pedal build from scratch that I would try the MXR Distortion + vero build here:
http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album17/album06/mxr_dist_plus_001.jpg.html?g2_imageViewsIndex=1

I finished off the vero work and wired up all the switches, jacks, etc. I just stuck with 9 battery connection for now though.

I hooked up the circuit to my amp and guitar, and got dry sound on bypass, and nothing on effect on. I later on realised that I completely forgot to install the LM741 in the socket!

I did this and tried again. With the LM741 I get a chirping, clicking sound with the guitar sound dropping in and out. With the effect on it speeds up a bit with the clicking, and not really any guitar sound.

Any ideas what this might be? Also, looking at the diagram, is the green ground wire on the 1meg drive pot supposed to branch across the two lugs on the pot? I've done this.

Here's a pic of what I have wired. Using the continuity meter I appear to get signal across the switch, the pots in and out, etc.

Thanks in advance for your help.

[MartyMart]

Hi, first it looks like your drive and volume pots are wired in reverse, the little picture in the layout
shows the back of the pot, with the shaft pointing away from you and hidden.
That will change their behaviour and they will work backwards as you turn them !

Yes the green wire does go across middle and one outer lug on the drive pot.

I would get the switch off at first - this can cause all kinds of problems if wired incorrectly.

Just go in/out of circuit from jacks and get that working.

Did you cut all the traces with the red square "dot" ?
Make sure these are clean cuts and also that there are no solder bridges anywhere. ( check with DMM for no continuity )

MM.

[LonePhantom]

Thanks for your response.

I realised when I tried the circuit they were in reverse. I wasn't too worried as I still need to house the circuit and was going to fix it then.

I'll double check the switch again. It looked all good to me, but I'll go over it again.

I did cut all of the traces, I've gone over them a few times with a stanley knife, but I'll check with the continuity meter again. I can't see any solder bridges either, the solder points all look pretty good. I will go over them again though.

[arma61]

Hi m8

have a look here

http://www.diystompboxes.com/smfforum/index.php?topic=74691.msg607418#msg607418

IIRC it looks like that layout is missing a trace cut

Ciao
Armando

[LonePhantom]

Thanks a lot for that! I would never be able to work that out from the schematics and stuff.

I'll try this, and check my wiring at the switch again tonight.

Cheers

[MikeH]

Man, I really wish Andy would fix that layout or take it down.  Seems like every few months there's a thread where someone is trying to debug this layout and doesn't know there is a missing trace cut.  I got burned by it like 4 years ago.

[IvIark]

Just had a quick look and it looks as though it needs a track cut between the positive lead of the 1u electro and the top of the 1M resistor, just below the opamp.  Just put a cut in at the 8th row, 11th column and that should sort it.

Edit: Doh sorry didn't see the link already posted.

[LonePhantom]

I cut the trace this evening, and hooked up my guitar and amp again. On bypass I got a dry tone, with a little extra noise. I'm guessing that because the circuit isn't enclosed yet that I was getting some interference?

When activated I got some distortion, a little faint and buzzy though. I'm going to house everything and go through the circuit with the continuity to make sure all traces are cut properly.

Thanks for pointing me to the fix for the circuit. I'll let you know how I go over the weekend after checking the trace cuts and housing it.

[petemoore]

  If you're mediocre with a DMM, the switch/signal paths can be effectively traced through/verified, almost as good as just testing the circus board without the 'extra complications' of Sw., Jaxx etc.
 For input trace, start maybe with:
 Plug cable in the input, put DMM [beep mode] lead on the cable tip [open end of the cable] the other DMM lead on the input...first components input side [.01uf IIRC]...hit the switch once, in one of the two switch modes the DMM should indicate that between the guitar output jack tip and the circuit input there is continuity. If not start with shorter tracings [test cable {test jack tip/lug {test wire to switch etc. until the block is located.
 For teh circus board you'll need to try completing debugging chores, how to develop debugging chops is explained in the debugging sticky.
 
  http://www.diystompboxes.com/smfforum/index.php?topic=29816.0
 

[LonePhantom]

I just checked all of the trace cuts, and strips, and all are good.

I'll get to work on housing it, and go over my jack and switch wiring while I'm installing everything.

[petemoore]

 That might require uninstalling everything to find the problem.

[LonePhantom]

I installed the circuit in it's enclosure yesterday, and redid my wiring tonight. I'm pleased to report that I got it working on battery power. I don't have enough room in the enclosure for a battery as I did a bad job of selecting my jacks (too big, will get different ones next build), and my general layout in the enclosure wasn't quite the most efficient. I'll be wiring in a DC jack anyway as I use a Pedal Juice to power my effects, so it's all good anyway.

Thanks again all for your help, I'm very happy to have managed to build a slightly more complicated circuit after my LPB-1 build.

[arma61]

Well done m8

what's next ?

Cheers
Armando

[LonePhantom]

Thanks

Next project (which I hope I don't completely stuff up) is a Bad Stone, I ordered the PCB from the group buy a few weeks back. Hopefully I can get it working without any real issues.

I am considering however building one more vero build first just to get a bit more proficient with this stuff. The two knob high gain build from here looks and sounds pretty cool.

[LonePhantom]

Just another question regarding this build. I'd like to put in a switch to go between two different pairs of diodes, one pair as the original diodes, and the other a pair of red LEDs. I understand that I would use an SPST switch for this, but how would I add it to this vero layout?Do I add a wire with the diode pair on each of the points the diodes are placed on the original layout? Not sure if this makes sense, but I'm sure plenty can help.

Could I install the diodes on a seperate small piece of vero too to keep things a little neater with the wiring?

[LonePhantom]

Whoops! meant SPDT switch of course.

[LonePhantom]

Also, I've noticed the drive pot seems to be an all or nothing affair, most of the distortion occurs towards the end of the pot's range. can I use a better rated pot, or through a resistor on it somewhere to make the usuable range of dirt cover the whole swing of the pot?

[rousejeremy]

Also, I've noticed the drive pot seems to be an all or nothing affair, most of the distortion occurs towards the end of the pot's range. can I use a better rated pot, or through a resistor on it somewhere to make the usuable range of dirt cover the whole swing of the pot?

Are you using a reverse log pot?

[LonePhantom]

Are you using a reverse log pot?

I don't know that I am? I don't remember my local electronics store having them.

[rousejeremy]

Getting one will solve your problem. Check this out. http://www.geofex.com/article_folders/potsecrets/potscret.htm