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Colorsound Power boost noise issue

Andy Betts

A while ago I posted regarding transistors etc for a Colorsound Power boost clone pedal I was working on. Well, after many months I've actually finished 2 of them... They are identical to an original right down to the size of the PCB.and the components used. There is one slight difference in so far as the first board was a direct print from an Eagle layout, the second board was a 121 trace of an original PCB, only slightly different from the eagle board.

 

This is the Eagle board

This is board 2, a 121 copy of an original Colorsound Power boost PCB, and also a photo of an original

 

The component side is like this.. mine is on the left, the genuine PCB is on the right. The pots on my board are mounted to the board like the original... Just from the other side. The reason for this is purely down to the thread length on the pots. The thread on my pots isn't long enough to go through the PCB, and then through the enclosure as well.

 

20264850_10155652356109783_7777668817152516572_n.jpg?oh=d17440c16b7064d06164d2a2c9783dba&oe=59EEEC46 

 

The schematic used was this one..... a simple circuit which is basically a pre-amp that boosts the volume and treble and bass.

 

 

The components on the first board were all brand new, where the components on the 2nd board were mostly NOS for a visual vintage vibe.

 

I have an issue on both boards that I'm trying to troubleshoot, and currently i have reached out to 2 DIY effect pedal forums with no real resolution. i'm hoping someone here may be able to point me in the right direction, i'll try to give as much information as possible.

 

I have a cycled ticking noise that increases in volume when you turn the volume up on the pedal. it's not affected by the guitar volume, and stays there even when you turn the guitar down. Check out this video.

 

This video is unavailable.

 

This video is unavailable.

 

This video is unavailable.

 

The last video shows a slight earth problem that may or may not have anything to do with the noise. i thought i'd include it anyway.

 

I have taken voltage readings off my pedal, and compared them to the readings from a genuine pedal (I'll say at this stage that my pedal is exactly the same as the genuine pedal as regards component values)

 

Genuine Pedal voltages

Battery: 18.84V

Q1 C 6.43V B 3.92V E 3.54V

Q2 C 11.53V B 6.44V E 5.82V

Q3 C 10.19V B 2.77V E 2.23V

 

 

My voltages:

Battery: 18.80V

Q1 C 6.37V B 3.90V E 3.52V

Q2 C 11.36V B 6.37V E 5.74V

Q3 C 10.54V B 2.75V E 2.19V

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  • 0

    Ok chaps... Updated video.

     

    This time I've ran the pedal through my live stage system.

     

    The result is there is still an audible motor boating noise, and I'm at a loss as to what could be causing it

     

    This video is unavailable.

  • 0 in reply to Andy Betts

    We need to see that noise on a scope !

     

    Can you record it as a .wav file somehow - idelly direct - not though  a speaker and microphone.

     

    Does it do the same in this rig with the shorting plug instead of the guitar.

     

    MK

  • 0 in reply to michaelkellett

    Michael, can you do me a favour... Plug the guitar into the pedal, and the pedal into the amp. Turn the bass and treble to 12 o clock, and the gain right up... Then start to turn the guitar volume down... What happens??

     

    What happens here, is that motor boating is very loud when the guitar is turned right the way down.

     

    I've tried the shorting plug, and the result is positive... There is NO noise, just the hiss of the circuit.

     

    At the recommendation of Ian Dempsey over at the DIYstompbox forum, i tried soldering a 10k resister into the input jack, and it appeared to reduce it slightly.

     

    So, at the moment the status is this.....

     

    • There is only motor boating when the guitar is plugged into the pedal.
    • Without the guitar plugged into the pedal, and holding the input jack in my hand, you get the normal buzzing noise where you're shorting the tip and ground... when you turn the gain up there is NO motor boating.
    • When you place a shorting plug into the input socket, there is NO motor boating just the hiss of the circuit
    • When you plug the guitar in, and turn the gain up on the pedal, and turn the volume down on the guitar you get motor boating.
    • I have tried my sons bass guitar in the pedal, and it motor boats ONLY when you turn the guitar volume down.... When the guitar volume is up it's OK
    • My friend at work has tried my pedal, and said it worked OK no issues
    • Ian Dempsey has made his own pedal from my circuit layout and Electric Warriors schematic, and it works OK
    • Michael Kellett has tried the pedal and has had no issues.

     

     

    Aside from all that... I have now brought the guitar, pedal, practice amp and leads into work, i'll try it out here and see what happens.

  • 0 in reply to Andy Betts

    Hello Andy,

     

    I'll do that but not today because the dog is with me (she usually is on weekdays)  and she doesn't like the sudden load noises these experiments make. Should be able to do it on Saturday, or possibly tomorrow: depends if anyone at home wants to play with the dog !

     

    MK

  • 0 in reply to michaelkellett

    Michael

     

    Don't bother with that test. Just send the pedal back to me.... I'll sort out the postage for you, just let me know how much, and I'll pay pal you the money.

     

    Address is:

     

    Andy betts

    11 St Benedict's Close

    Sudbury

    Suffolk

    CO10 1AF

     

    I have taken the pedal and guitar to work, plugged it in and it's working perfectly, no oscillation at all either at full gain, or with the the guitar volume turned off. It has to be something to do with the house, or something. RF interference from somewhere...

     

    This has proved that the pedal works as you and Ian Dempsey have said, and that also the guitar is fine. There has to be some kind of interference in my house or something.

     

    I now need to find the root cause of the interference..... Any suggestions?

  • 0 in reply to Andy Betts

    I can think of two things - both guitar related:

     

    1) the pot on the guitar is faulty so that at min volume the wiper isn't shorted to earth but open circuit so you pick up load of noise.

     

    2) some other wiring fault on the guitar.

     

    I'll post it to you tomorrow - can't get out today - don't worry about the post money - it's been interesting.

     

    MK

  • 0 in reply to michaelkellett

    Thanks Michael,

     

    I have a very good update...... I think I've discovered what's causing the issue.

     

    I got home from work early, and while there was nobody in the house I started turning things off...... And this is what happened.

     

    This video is unavailable.

  • 0 in reply to Andy Betts

    Hi Andy,

    This is great news and very typical of how most of the really hard problems are resolved. I am glad you didn't give up. Now that you are part of the group I hope you hang around and keep us posted on the progress with your color sound pedals.

    John

  • 0 in reply to violet

    Shielding inside the enclosure... I think I may have some sticky backed copper shielding which I used ages ago when I built the guitar...

  • 0 in reply to jw0752

    John, this is only the beginning

     

    I have built another pedal actually, based on a very early design.... very simple. the famous Fuzz Face. The board is populated, I just need to wire it up and test it..... But that's for another thread

  • 0 in reply to Andy Betts

    Interesting find : ) I've forwarded it to a friend who works there, although not a set-top-box team, just for some more visibility at Sky.

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