Author Topic: Flabulanche Noise problem  (Read 348 times)

ThatGuyThere

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Flabulanche Noise problem
« on: July 26, 2019, 01:41:27 PM »
I am having a problem with my Flabulanche pedal that recently put together.  It is generating a consistent wooshing sound that is quite annoying.  It not abundantly evident when the volume and gain are down, but it is there. 

https://www.youtube.com/watch?v=Stc_iqgUMSI&list=LLvrkVZzl881pS6qpnJDkWAw&index=2&t=0s

I also, am not seeing any change in the Q3 values if I change the switch for the compressor. 
Here is some data:
Before D2:  9.16v
After D2:  8.94v
Test Point 1:  11volts
Test Point 2:  Bouncing around ALOT 1 to 11.24 volts
Test Point 3:  13

Q1
D  11
S  0.552
G  0  (lots of buzz when testing)

Q2
D  11.26
S  0.629
G  0

Q3  Comp. Switch left        Q3  Comp. Center           Q3  Comp. switch right
D  13.04                           D  13.11                        D  13.04
S  0.296                           S  0.29                          S  0.296
G  0.011                          G  0                               G  0.012

D1  switch left                    D1  center                    D1  switch right
3.18                                   0.17                            3.25

Q4
D  10.71
S  3.63
G  1.50



I am not sure why the compressor circuit does not seem to be doing much to effect the Q3.  Any ideas?  Also, the annoying noise which seems to grow somewhat more complex as it is on longer.  Is that an oscillating sound?  Could this be the LT1054 chip?  Transistor?  Filter capacitor?
Thanks for your help,
Tyler

ThatGuyThere

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Re: Flabulanche Noise problem
« Reply #1 on: August 15, 2019, 08:49:19 AM »
I am still having a problem with my Flabulanche pedal.  This one just befuddles me!  I figured out the wooshing sound described above is from the stupid wall wort.  It went away with a battery clip.  However, I am still getting a static sound that is like a percolating coffee maker.  (I switched out the LT1054 and there was no change) Meaning, it does not really have any consistent pattern.  Also, it will play nicely despite the static for about 10-15 seconds and then the signal seems to get swallowed up and is barely perceptible and the static takes over.  I am wondering if this is from one of the FETs reaching a saturation point on the gate that is preventing any signal to pass? 

I continue to not seeing any change in the Q3 values if I change the switch for the compressor. 
Here is some data:
Before D2:  9.16v
After D2:  8.94v
Test Point 1:  11volts
Test Point 2:  11.04 volts
Test Point 3:  11

Q1
D  11
S  0.552
G  0 

Q2
D  11.06
S  0.673
G  0.077

Q3  Comp. Switch left        Q3  Comp. Center           Q3  Comp. switch right
D  11.01                           D  11.08                        D  11.00
S  0.296                           S  0.29                          S  0.295
G  0.009                           G  0.001                        G  0.009


Q4
D  10.94
S  3.56
G  1.426

Q5
D  9.02
S  9.02
G  9.4

Q6
D  11.09
S  11.09
G  9.37

Q7
C 17.17
B 9.52
E 9.37

I am not sure why Q3 has no voltage on the gate on the high and low settings.  I had changed the D1 to a Schottky BAT41 diode per Jon Patton's advice on this post:
http://www.madbeanpedals.com/forum/index.php?topic=24379.msg254196#msg254196
When I measure the voltage between R8 (33k) and C6 (22n) I get around 11 volts.  But between the C6 and the gate of Q3 I get the very low voltages listed above (0.009v).  Does this make any sense to anyone?  Could this be the reason that the guitar signal seems to disappear?  I guess that I do not totally understand the compression circuit on this pedal. 

Please help,

Tyler

EBK

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Re: Flabulanche Noise problem
« Reply #2 on: August 15, 2019, 11:24:51 AM »
Could you post some pics of your board?
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ThatGuyThere

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Re: Flabulanche Noise problem
« Reply #3 on: August 16, 2019, 11:44:57 AM »
Here are the pictures of the front and back of the board.

Notice that I had a previous issue with the board (?) where the trace seemed to be missing between the filter caps and the IC.  I subsequently jumpered the connection to pin 8 on the LT1054 from the 100 uf capacitor and the 100n cap is also kind of attached to the jumper as best as I could make it.  That being said, I am getting full power to and from the IC.  I changed ICs to see if that was causing any problems and it did not effect the static issue.
Tyler


« Last Edit: August 16, 2019, 12:13:35 PM by ThatGuyThere »

midwayfair

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Re: Flabulanche Noise problem
« Reply #4 on: August 16, 2019, 04:16:52 PM »
Check that T2 is fully soldered. Reflow your solder joints on the power supply section and each transistor that looks even remotely dodgy.

I'm not sure what's going on in your lower left, but make sure that stuff is all well-soldered.

Measure the voltage on both sides of D1. (But it's possible that the resistance of your diode is high enough that it's not affecting the voltage on the other side.)

The compression is explained in the original post and in the build doc. The negative voltage from the amplified guitar signal rectfied by the diode pulls the gate negative and decreases the gain of Q4.
Myself's music & things I make: http://jonpattonmusic.com. My band: http://midwayfair.org. PCBs of my designs from: http://www.1776Effects.com (Bearhug Comp & Cardinal Harmonic Trem); http://www.jmkpcbs.com (Hamlet+ delay & Blue Warbler envelope vibe); Snow Day OD/Flabulanche: www.madbeanpedals.com

ThatGuyThere

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Re: Flabulanche Noise problem
« Reply #5 on: August 18, 2019, 09:13:31 AM »
It works!!!  Thanks so much for the support.  Like most problems in life, it turned out to be a matter of a simple problem wreaking havoc.  I reflowed all of the transistors and the trim pots and the potentiometers.  Not sure which one was the issue, but it is a noticeable improvement. 
Now I just need to build a clean power supply!  Any suggestions?
Thanks,
Tyler

midwayfair

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Re: Flabulanche Noise problem
« Reply #6 on: August 18, 2019, 12:16:34 PM »
Now I just need to build a clean power supply!  Any suggestions?

Buy a one-spot.

Building a power supply is expensive and dangerous.
Myself's music & things I make: http://jonpattonmusic.com. My band: http://midwayfair.org. PCBs of my designs from: http://www.1776Effects.com (Bearhug Comp & Cardinal Harmonic Trem); http://www.jmkpcbs.com (Hamlet+ delay & Blue Warbler envelope vibe); Snow Day OD/Flabulanche: www.madbeanpedals.com