Help with Big Muff Pi clone (green russian version)

Started by jfrabat, June 23, 2019, 11:38:57 AM

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jfrabat

OK, after some debate about my next project, it was pointed our to me I needed a Big Muff Pi (to which I agree!).

So, I did a perf board version, and could not get it to work...  Given how bad my soldering was, I decided it would be easier (and faster) to just get a PCB and make one that way.  I decided to try out this version:

https://buildyourownclone.com/products/lil-beaver-russian-kit

I did not buy the kit, only the PCB.  Anyway, instructions for the pedal are here.  Here is how my board looks as of now:





Some differences from the original is that I have2N5088 instead of 2N5089, but pinout is the same.   I also used the LED ring stomp switch, so the CLR is different (and that is working fine; LED intensity is spot on).  And the .0039uF was replaced with the closest I had (in this case, it's labeled .0047uF, but the actual reading was .00445uF, which was the lowest reading .0047uF of my stash).

Now, the issue I have is that when I connect to my test board to try it out, I am getting no sound when I activate the pedal (bypass works great).  Also, if I disconnect the battery, I get a sound coming through (lower volume than bypass).  In the enlarged image, I saw some solder points that could be causing a short, so I touched them up a bit (I did not take a picture after the correction, sorry).  I also checked diodes, and they are in the right direction.  But still, no sound.  Any ideas where I could have issues?  And does anyone got voltage readings for a Green Russian to compare to?

Felipe
I build.  I fix.  I fix again.  And again.  And yet again.  (sometimes again once more).  Then I have something that works! (Most of the time!).

jfrabat

Never mind... Just noticed the missing resistor!!!
I build.  I fix.  I fix again.  And again.  And yet again.  (sometimes again once more).  Then I have something that works! (Most of the time!).

jfrabat

Well, that was not it...  I checked all the resistor values (only CLR is different as per the switch requirement), all the caps values (only 3.9 switched for 4.7), all the diodes (type 914 and polarity), transistor placement (2N5088 used instead of 2N5089, but checked pin-outs and they are the same), possible shorts...  I am stumped.  Any help is welcome.
I build.  I fix.  I fix again.  And again.  And yet again.  (sometimes again once more).  Then I have something that works! (Most of the time!).

sominka

Check every thing again...
Test it works before boxing? You do that don't you?

jfrabat

Quote from: sominka on June 23, 2019, 12:27:48 PM
Check every thing again...
Test it works before boxing? You do that don't you?

Box is not even ready...  I never touch the box until the pedal works.
I build.  I fix.  I fix again.  And again.  And yet again.  (sometimes again once more).  Then I have something that works! (Most of the time!).

Ice-9

It looks like you have not got the ground wires soldered onto the PCB for the in/out jacks.
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Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

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jfrabat

Quote from: Ice-9 on June 23, 2019, 02:08:25 PM
It looks like you have not got the ground wires soldered onto the PCB for the in/out jacks.

That is on purpose.  On my test rig they go directly to ground.

I actually found the problem.  When I replaced the CLR resistor, I swapped the wrong one.  Caught that on the second check...  It is working now.
I build.  I fix.  I fix again.  And again.  And yet again.  (sometimes again once more).  Then I have something that works! (Most of the time!).