Troubleshooting RC Booster - Pics and Voltages inside

[digidoc1010]

I just completed an Xotic RC Booster type pedal and am having a problem.  Here is the information I have collected so far.

It only produces sound if the Treble is all the way UP AND the Bass is all the way Down.  The volume pot has no effect.  The drive pot seems to work appropriately.  When it does produce sound, it is very clear and bright and sounds like I would imagine it should with the volume all the way up.  However, if I adjust the Treble down at all it cuts out or if I adjust the Bass up at all it cuts out.  It doesn't cut all the way out, but is so quiet that it may as well be off.  True bypass works.  Pictures of the diagram and of my board are included.  BTW, in the picture of my board there is a piece of solder next to where the 9v cable enters the board.  That has been removed and the problem remains.  Thanks so much for any help you can provide!

2.Name of the circuit = Xotic RC Booster

3.Source of the circuit (URL of schematic or project) = http://tagboardeffects.blogspot.com/2012/10/xotic-rc-booster.html

4.Any modifications to the circuit? No

5.Any parts substitutions? IC - Substituted an NJM4558D for the JRC4558

6.Positive ground to negative ground conversion? No

7. Voltage Measurements - Refer to schematic.

Q1 = 2N5088BU http://www.mouser.com/Search/ProductDetail.aspx?R=2N5088BUvirtualkey51210000virtualkey512-2N5088BU
C = 9.41
B = 2.53
E = 2.17

Q2 = 2N5088BU http://www.mouser.com/Search/ProductDetail.aspx?R=2N5088BUvirtualkey51210000virtualkey512-2N5088BU
C = 9.41
B = 4.09
E = 3.70

IC = NJM4558D http://www.mouser.com/Search/ProductDetail.aspx?R=NJM4558Dvirtualkey51310000virtualkey513-NJM4558D
P1 = 4.67
P2 = 4.67
P3 = 4.67
P4 = 0
P5 = 4.67
P6 = 4.67
P7 = 4.67
P8 = 9.41


Diodes = 1N4148 http://www.mouser.com/Search/ProductDetail.aspx?R=1N4148virtualkey51210000virtualkey512-1N4148

D1
A = 4.18
K = 4.67

D2
A = 4.42
K = 4.18

D3
A = 4.67
K = 4.42

D4
A = 4.67
K = 4.43

D5
A = 4.42
K = 4.18

D6
A = 4.18
K = 4.67

[tubegeek]

Not sure I'd expect IC1 Pin 7 to be higher than the other 4.67 V pin voltages - double check to see if there is solder bridging the Pin 7 strip to the +9V strip? (6th from top & 5th from top respectively.)

Op amps typically are all very close to Vref except +V and -V (8 and 4.)
Here's a schematic too:

[GibsonGM]

+1, pin 7 seems off.   Do you have an audio probe?  You might be able to hear signal up to about that point, and confirm that something is miswired near there....the audio probe is irreplaceable!   Search if you need to know how to make one.   That would be MY next step....pin 2, pin 1, pin 6, pin 7, while someone hits your guitar strings...

[digidoc1010]

Thanks so much for the feedback so far.  I'll check for bridges and see if I can find out what is going on at pin 7.  Thanks also for the tip about the audio probe.  Off to research it now.  I'll report back my findings.  Thanks!

[digidoc1010]

I just rechecked my voltage at pin 7 and I must have accidentally touched another pin when I measured it the first time...now it measures at 4.67 as expected.  Sorry about that.  I've updated my original post with the corrected voltage.

[GibsonGM]

I re-read your first post...ok....are you sure the treble and bass pots are the correct value?

If so, check for shorts around R11, R10 on the schematic (of course, that means you have to find them on vero)...that square.    Think of what's happening when you turn the pots all the way - you are bypassing a section of circuit.  So, if that makes it work, then the problem is in the part you just jumped over (hope that makes sense).     My gut = something is shorted.     Post a pic of the BACK of the board, too.

Check pin6 and 7 voltages when you turn pots to get NO sound - do they change?   

<this is why I so dislike Vero - I know where your problem is, but now we have to locate it on the vero AND make sure you don't disturb something else while correcting it.  Rrrr>

[The French connection]

There's something bubbling around the red wire and the long jumper...maybe there's a bridge or short there. Go between every strip with a exacto knife to remove any possible solder bridge...Something i do everytime i use vero. Show us the other side of your vero...and pots wiring.

[digidoc1010]

Success!!  There must have been a micro bridge.  I did as suggested and went back over every row with an exacto knife and now it works perfectly.  I really like this pedal a lot.  It adds so much clarity to my sound.  I'm playing a Les Paul through a Dr. Z Maz 38 and I just can't get over how much of a difference it makes.  I thought it sounded great before, but now I feel like it is so much clearer.  It is a pedal I will leave on all the time.

Thanks so much everyone for your help!  This is my first experience on this forum and I am so impressed with how quickly you responded and the clear advice you gave.  You guys are awesome!

Dan

[The French connection]

Success!!  There must have been a micro bridge.  I did as suggested and went back over every row with an exacto knife and now it works perfectly.  I really like this pedal a lot.  It adds so much clarity to my sound.  I'm playing a Les Paul through a Dr. Z Maz 38 and I just can't get over how much of a difference it makes.  I thought it sounded great before, but now I feel like it is so much clearer.  It is a pedal I will leave on all the time.

Thanks so much everyone for your help!  This is my first experience on this forum and I am so impressed with how quickly you responded and the clear advice you gave.  You guys are awesome!

Dan

Congrats!  Always pass the knife between row when you use vero. It will save you a lot of time!

[tubegeek]

Sweeeeet!