Rullywow Voodoo Return, ala Axis Fuzz...voltages.

[Outlaws]

Rullywow Voodoo Return

There isn't much online for this board specifically. But I haven't tossed it in a box yet, just assembled the PCB and pots.  I used all the suggested stuff with the exception of the diode, that's a 5818 instead of 5817, and while I don't understand the differences in diodes, google said it was kosher and that's what was instock.  I have one now though if I need it.

Okay the sound... well with a Les Paul this thing sputters with the guitar volumes full on and the fuzz all the way up.  I don't have a single coil strat anymore, and I know lots of fuzzes don't like humbuckers, but I want to know if stuff is right.  It sounds okay with the guitar backed off a little, but it's nothing mind blowing.  It has a very "fizzy" texture over it.  That could well be the Axis Fuzz sound, I don't know, I just built it for fun.

Here are the voltages.  I feel like Q2 is high, and not sure why, but the voltage jumps .5v every few seconds like clockwork. ...with a battery and no chips, this confuses me, but whatever.

I measured everything from ground, so i don't know if that matters with a PNP and NPN tranny, but it's +9 so let me know if I accidentally measure voltage drops on one tranny.

• Q1
  C 3.8v
  B 5.35v
  E 5.98v
  
  Q2
  C 7.2v (jumps to 7.7v)
  B 3.3v-3.7v (random movement)
  E 4.8v

[Cozybuilder]

Looking at the Rullywow schematic V 1.0, the Q1 (2N3906) has the emitter arrow drawn backwards, this is a PNP transistor. The voltages on Q1 look about right. The base of Q2 should be the same as the collector of Q1, and should be about .6V higher than the emitter of Q2. Your Q2 emitter is higher than the base, look at R8, it should be 39K, do you have a higher value there?

[Outlaws]

Looking at the Rullywow schematic V 1.0, the Q1 (2N3906) has the emitter arrow drawn backwards, this is a PNP transistor. The voltages on Q1 look about right. The base of Q2 should be the same as the collector of Q1, and should be about .6V higher than the emitter of Q2. Your Q2 emitter is higher than the base, look at R8, it should be 39K, do you have a higher value there?

It's a 39k resistor at R8. Orange White Orange.  I guess if I lower this a bit the emitter voltage drops.  I can try dropping it.  Would this mean the tranny is basically doing its tranny thing too much?

[Cozybuilder]

I would check the solder first, the transistor is acting like its not connected to ground.

[Outlaws]

I would check the solder first, the transistor is acting like its not connected to ground.

Well I swapped in a old 100k trimmer. This doesn't fix it, but I think I increased the resistance a bit and it has less and got me closer to spec. Q2 C:6.16v B:3.72v E:3.15v  What's odd is even the collector V smoothed out and went down. No jumping. But my continuity test is all over.  With the battery connect I have no continuity to ground.
From both sides of the resistor I have continuity. From the actual leg of the E on Q2 I get a reading that jumps but is about 1Mohm.

[Cozybuilder]

Can you post photos of your board, front & back? It sounds like a ground problem, which could be from a number of different things. Maybe one of us can spot something.

[rumbletone]

Re the 'fizzy' texture, what are you running it into? I find many of these don't sound great into a clean amp - but run them into a Marshall that's just breaking up and they start to shine.


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[Outlaws]

Can you post photos of your board, front & back? It sounds like a ground problem, which could be from a number of different things. Maybe one of us can spot something.

The back is hard to see since there are pots covering it.  But there are no bridged solder traces I can see.  I try to be very cognitive of that.

[Outlaws]

Re the 'fizzy' texture, what are you running it into? I find many of these don't sound great into a clean amp - but run them into a Marshall that's just breaking up and they start to shine.


Sent from my iPhone using Tapatalk

Its the clean channel of my Mark V.  I run a Tone Bender into and love it.

[Cozybuilder]

From what I can see, the resistors are the right values, the electros and diode are oriented correct, the soldering looks fine. Q1 is a 2N3906, right? Do you have good ground contact at the input and output jacks?

[Outlaws]

From what I can see, the resistors are the right values, the electros and diode are oriented correct, the soldering looks fine. Q1 is a 2N3906, right? Do you have good ground contact at the input and output jacks?

Ya.  I took it to a buddies and plugged in his strat. World of difference. Sounds fantastic. I think it just hates my humbuckers.  Now I just have to decide if I want to put back in the 39k or use something close the 55k my trimmer is at.

[Outlaws]

http://www.rullywow.com/wp-content/uploads/2016/01/Voodoo-Return-Fuzz-v1.0.pdf

So if I wanted to goose a little more output from this, can I just lower a resistor value? The bypass signal has more impact.  Schematic is on page 3.

[Cozybuilder]

You could replace R4 (10K) with a 5K (new R4) fixed and 5K linear pot in series between new R4 and R10 (22K fixed). Connect C7 (2u2) to the 5K wiper - that'll give you volumes from where it is now to a substantial increase.

Oops  , you need to do this with R10- replace the 22K with a fixed 12K at the collector and a 10K linear pot between that and R4, C7 on the wiper.

[Outlaws]

You could replace R4 (10K) with a 5K (new R4) fixed and 5K linear pot in series between new R4 and R10 (22K fixed). Connect C7 (2u2) to the 5K wiper - that'll give you volumes from where it is now to a substantial increase.

Oops  , you need to do this with R10- replace the 22K with a fixed 12K at the collector and a 10K linear pot between that and R4, C7 on the wiper.

So following this... I could remove R4 and R10 offboard...run a wire from the north hole in that layout of R4 with that 10k resistor tapped to a 10k trimmer leg 1, run a wire from the north hole of R10 to a 12k resistor and onto leg 3 of the trimmer, and run the trimmers 2nd leg wiper to that south hole of R10s spot that connects to C7.
I would be lifting both resistors off the board as I realize the south side of both are connected to C7.
I feel certain I am right in what I am seeing.

[Cozybuilder]

It looks like there is enough room on the board to mount a 10K trimmer next to R10, and no PCB leads in the way. Drill 3 tiny holes to mount it.

e.g.:  http://www.mouser.com/ProductDetail/Bourns/PV36W103C01B00/?qs=sGAEpiMZZMvygUB3GLcD7lv7xXtevcsqvK8peaGZgso%3d

I would remove R10, and replace it with an ⅛ Watt 12K, soldering one end to the pad connecting to Q2C, and drilling a tiny hole short of the pad to R4 and C7. Now, connect the unsoldered lead to one of the trim pot ends, using a short piece of insulation on the resistor lead.

e.g.: http://www.mouser.com/ProductDetail/Xicon/270-12K-RC/?qs=sGAEpiMZZMu61qfTUdNhG%2fc5AtEINLt%2fw8tidhfN2As%3d

Now, remove the connection between C7 positive and the pad leading to R4 and the former R10. Connect the C7 positive lead to the wiper of the trimmer. Finally, connect R4 at the pad you just freed to the other end of the trimmer.

[Outlaws]

Well I got assured of myself and did it. Thanks for the reply and the help. It works. I'll post a pic in a few minutes.

[Outlaws]

It looks like there is enough room on the board to mount a 10K trimmer next to R10, and no PCB leads in the way. Drill 3 tiny holes to mount it.

e.g.:  http://www.mouser.com/ProductDetail/Bourns/PV36W103C01B00/?qs=sGAEpiMZZMvygUB3GLcD7lv7xXtevcsqvK8peaGZgso%3d

I would remove R10, and replace it with an ⅛ Watt 12K, soldering one end to the pad connecting to Q2C, and drilling a tiny hole short of the pad to R4 and C7. Now, connect the unsoldered lead to one of the trim pot ends, using a short piece of insulation on the resistor lead.

e.g.: http://www.mouser.com/ProductDetail/Xicon/270-12K-RC/?qs=sGAEpiMZZMu61qfTUdNhG%2fc5AtEINLt%2fw8tidhfN2As%3d

Now, remove the connection between C7 positive and the pad leading to R4 and the former R10. Connect the C7 positive lead to the wiper of the trimmer. Finally, connect R4 at the pad you just freed to the other end of the trimmer.

It works.  Thank you again.

Here is my take on doing what you suggested.  I already had the board in the box since it sounded amazing with the strat last night.  I presume the volume issue is more due to humbuckers obliterating the input as when I back off my guitars volume to about 3, the effect is still way louder than the bypass, even pre mod, but with the volume up there are no dynamics left.  But just for the sake of it, i like the idea that there is more on tap.  This mod didn't add a ton of output.  its barely noticable, but its just enough I don't totally feel like if I turn it on I am losing volume.  That said....I will honestly never ever use this with a Les Paul again, its just not a good fuzz for it lol.  Strats are its thing.

[Cozybuilder]

Thats great, glad you have it working right now. I like strats and P-90 Juniors best, but will always keep some humbucker equipped guitars around.

In this board's tradition, you get a prize for perseverance: