Build Your Own Clone Message Board

Hello,

This is my second pedal build. First was a fuzz face that worked out well.


1) I purchased the PCB for a lil beaver rams head. Put it all together, and I'm not getting any sound on the output.

2-5 Pictures in this album https://photos.app.goo.gl/VfAw9uLeWX5uT7UN7

6. Is bypass working? Yes, bypass works fine.
7. Does the LED come on? Yes.
8. If you answer yes to 6 and 7, what does the pedal do when it is "on"? Sometimes very very low volume sound
9. Are you using a battery or adapter? (if it's a battery, is it good? If adapter, what type?) Battery only. Tried multiple batteries, all meter 9v or better.

To troubleshoot I built a signal probe which I am admittedly not great at using. Signal tone drops to almost nothing after the 33k resistor. It travels into the first transistor and is still very low volume. The transistors are 2n5088, so I have them oriented the opposite direction of what the board specs since i read the pinout is the opposite. I've reflowed the components so many times it is looking pretty sloppy, but the problem has not changed. I soldered one pot directly to the board to eliminate its wires as an issue. I've cut a few of the resistors to measure them out of circuit since I thought the readings were weird but they were fine out of circuit, so i soldered them back in.



Thanks for any help.

Not that it would cause this problem, but are you aware that you've mounted the footswitch and the LED to the wrong side of the PCB? Mounting the PCB into an enclosure will be a virtual impossibility.

I suspect your problem is solder-related. I would redo all the wire connections at the PCB, which look quite poor, and carefully work through this process: viewtopic.php?f=9&t=52188

I'd also recommend reading through these posts, to help improve your soldering and wiring technique.:

viewtopic.php?f=9&t=52211

viewtopic.php?f=9&t=6401

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks for the suggestions! I spent some time cleaning it up and changed the switch and led around like you said.

Right now it is working, but has some quirks.

1) the sustain knob acts as a second volume. Turning it down to zero reduces volume to almost nothing.

2) there are some weird fade/decay issues. I can play one note and it decays really fast. Play it again and it will sustain for a long time. Here is a link to a video of that and some pics of the cleaned up board. https://photos.app.goo.gl/jsF77keCforQ8SR9A

That sounds like it could be a transistor biasing issue. Do you have access to a multimeter and know how to measure DC voltage with one?

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Yes I can get voltages. Are you looking for voltages on all 3 legs for each of the 4? Anything else?

Here are the voltages when using a 9v battery that measures 9.79v

Q1
Collector 7.72
Base .618
Emitter .017

Q2
Collector 1.26
Base .76
Emitter .123

Q3
Collector .883
Base .274
Emitter .085

Q4
Collector 3.82
Base 1.64
Emitter 1.031

Your collector voltages for Q2 and Q3 are far too low--both should be up in the 3 to 4V range. Unless you have resistors in the wrong positions (I don't see this, but then again I can't see every resistor in your photos), the most likely cause is wonky solder joints around those transistors. I would suggest using the schematic and the labeled PCB diagram below to identify those components and confirm their values, then inspect, clean up and reflow their solder joints:

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

As far as I can tell, resistors are correct values.

After reflowing everything again, I now have 3.0v on q2 collector and 3.1v on q3 collector. No improvement in the decay issue, maybe slight improvement of sustain/volume issue.

I've linked some more pictures. I'm having a hard time determining what might need attention at this point.

https://photos.app.goo.gl/jVgYWXxTEM7eARJx5

Transistors backwards? Oops, never mind. Read the OP again.

Try changing R3 from 43k to 47k.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Increasing the value of R3 sure helped the sustain & decay behavior on my own RH Li'l Beaver. I ended up going all the way up to 100K on mine. I found some Ram's Head Big Muff schematics that showed values up to 100K for that resistor, so don't worry about going up that high, if it sounds better to you. You might want to try installing SINGLE INLINE SOCKETS in the R3 eyelets, which makes it easy to try different value resistors there without soldering and desoldering repetitively.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I went right for the 100k. Sustain/decay definitely improved, maybe even to normal (i've never owned a big muff).

However, the sustain knob is still acting like a volume. Anything below 1/2 on it and the pedal is almost inaudible.

Check to be sure that the solder joint at the top of resistor R24 is not shorting against lug 1 of the Tone pot direct above it. If it is, clean that up.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Just took a look, definitely no short there.

The sustain knob literally is a volume knob. You don't need to be able to fully understand everything that is going on in the schematic to get the "big picture". You should clearly see 4 distinct transistors stages. It is drawn very linearly, where signal travels from left to right, passing though transistor stage 1, then 2, then 3, then the tone stack, and finally 4. Stage 1 is a boost stage. You can see a passive volume control between the stage 1 boost and stage 2/3 clipping.

So the sustain knob doesn't control the active gain of a transistor or anything like that. It simply controls how much signal goes into the clipping stages.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Ok, just to confirm, you are saying this is normal behavior?

I will get it in a case and play with it and go from there.

Thanks!

Not 100% without actually hearing it, but probably. The BMP isn't known for doing light fuzz tones. Anything below 12 o'clock on the sustain knob is going to sound pretty anemic.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com