MI Audio - Blues Pro [traced]
- tonymcbony
- Breadboard Brother
Hi folks, I was just building a blues pro up on vero and I have the weirdest issue.
All the knobs work (Gain does *something*, tone and vol work as they should) but it doesn't amplify the signal, but instead cuts out every second, like a slow tremolo. I changed out all the power caps just in case that was the problem but no dice.
I was using this http://tagboardeffects.blogspot.co.nz/2 ... s-pro.html layout.
Things I did differently; I did not include the fuzz or fat switch. I instead put a jumper between that trace that both switches connect to and the + of the 22uF cap going to ground. I also used a 51pf in place of the 30pf
Voltages on the IC are:
1 bounces around
2 0.07
3 0.01
4 0
5 0.65
6 0.09
7 bounces around
8 9.02
I've changed IC's no difference too. Something weird is happening though!
All the knobs work (Gain does *something*, tone and vol work as they should) but it doesn't amplify the signal, but instead cuts out every second, like a slow tremolo. I changed out all the power caps just in case that was the problem but no dice.
I was using this http://tagboardeffects.blogspot.co.nz/2 ... s-pro.html layout.
Things I did differently; I did not include the fuzz or fat switch. I instead put a jumper between that trace that both switches connect to and the + of the 22uF cap going to ground. I also used a 51pf in place of the 30pf
Voltages on the IC are:
1 bounces around
2 0.07
3 0.01
4 0
5 0.65
6 0.09
7 bounces around
8 9.02
I've changed IC's no difference too. Something weird is happening though!
- DrNomis
- Old Solderhand
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tonymcbony wrote:Hi folks, I was just building a blues pro up on vero and I have the weirdest issue.
All the knobs work (Gain does *something*, tone and vol work as they should) but it doesn't amplify the signal, but instead cuts out every second, like a slow tremolo. I changed out all the power caps just in case that was the problem but no dice.
I was using this http://tagboardeffects.blogspot.co.nz/2 ... s-pro.html layout.
Things I did differently; I did not include the fuzz or fat switch. I instead put a jumper between that trace that both switches connect to and the + of the 22uF cap going to ground. I also used a 51pf in place of the 30pf
Voltages on the IC are:
1 bounces around
2 0.07
3 0.01
4 0
5 0.65
6 0.09
7 bounces around
8 9.02
I've changed IC's no difference too. Something weird is happening though!
That basically suggests to me that the circuit is motor-boating (oscillating) at a low frequency rather than amplifying, somehow the output-signal is being fed back into the input, have you tried turning the volume pot right down to zero and seeing if the voltage on pin 1 stops bouncing around?, if it does stop bouncing around then that suggests that the fault involves the volume pot....
Have you made sure that all the copper track-cuts have been made in the correct places?, also, check to make sure that you haven't made any unintended short-circuits between the tracks while soldering the components....
Hope that helps....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
- tonymcbony
- Breadboard Brother
Yep, that fixed the pulsing; I had 300k resistors instead of 330k.
Still doesn't actually raise the volume past unity for some reason.
Still doesn't actually raise the volume past unity for some reason.
- DrNomis
- Old Solderhand
Information
- Posts: 6807
- Joined: 16 Jul 2009, 04:56
- my favorite amplifier: Self-Built Valve Amp Head :)
- Completed builds: Dallas Arbiter Fuzz Face,Tone Bender Professional Mk 3,Tone Bender 3-Knob,Baja BK Butler Tube Driver,Baja Real Tube Overdrive,Roger Mayer Octavia,EH Soul Preacher,Tech 21 XXL Distortion,MFOS Weird Sound Generator.
- Location: Darwin,Northern Territory Australia
- Has thanked: 98 times
- Been thanked: 278 times
tonymcbony wrote:Yep, that fixed the pulsing; I had 300k resistors instead of 330k.
Still doesn't actually raise the volume past unity for some reason.
Hmmmm....a 300k resistor shouldn't have affected the operation of the circuit enough to cause the pulsing.....
Glad you fixed it though.....
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
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Hi !!
This is the MI Audio Blues Pro, i took the Tagboardeffects Rev 2, wich have the Fat Mode, and add to the premedit schematic:
Cheers !
This is the MI Audio Blues Pro, i took the Tagboardeffects Rev 2, wich have the Fat Mode, and add to the premedit schematic:
Cheers !