Help with Tonepad MXR Blue Box...please

[basscase]

Maybe someone can help me with this. I searched the forum and haven't found anything that deals with my problem.

I'm building the Tonepad MXR Blue Box clone (http://www.tonepad.com/getFile.asp?id=73). I finished the circuit and it works for the most part but there are several issues:

1. The blend pot doesn't work at all. I tried resoldering them on the board side with no changes, and they are getting full voltage. Also when I wiggle the leads or the transistors in the area the blend pot still doesn't work.

2. It sounds more like a garden variety octave fuzz (eg Jim Dunlop Hendrix octave fuzz) than a blue box. There isn't any random jumping between octaves or other goodness that is associated with the blue box.

3. I tried doing the two octave down switch mod using a 3-pole- two position on-on switch, but it doesn't work. I connected the middle pole to r11 at the side that would face the 4013 IC chip after removing that side from the board. I soldered the other two wires to pins 1 and 3 (which is connected to r13). The switch gets voltage but the voltage still goes to both sides when you switch it either way.

Substitutions:

1. I live in Japan, so I could only find the Toshiba TC4013BP instead of the CD4013. I checked the data sheet and they are both dual-d flip-flops and have the same pin layout. So they should be the same

2. I used a 100k audio pot for the blend instead of a 50k. I tried switching the blend and volume pots to see if the blend would work with a 50k pot and it didn't, but I know the pot isn't defective because the 100k worked at the output spot.

Other than that its completely stock. No negative to positive ground conversion or anything like that.

Voltages:

Voltage at the circuit board end of the red battery lead = 7.47
Voltage at the circuit board end of the black battery lead =7.44

Q1
C = 5.98-6.17 (fluctuates)
B = .65
E =.01

Q2
C=.20   .
B=.51
E= 0-.01

Q3
C=.34
B=.52
E=0-.01

IC1 (starting from the dot on the left side, going counter-clockwise)
P1= 3.68
P2= 3.75
P3= 1.78
P4=  0-.01
P5= 3.46
P6=3.46
P7= 1.45
P8= 7.36


IC2
P1= 0-.01
P2= 3.67
P3= 3.70
P4= 0-0.01
P5= 5.23 (fluctuates)
P6=0-.01
P7=0-.01
P8=1.96
P9=0.01
P10=2.66
P11= 4.64
P12= 3.13 (fluctuates)
P13=3.60
P14=7.32


.

D1
A (anode, the non-band end) = .01
K (cathode, the banded end) = 7.33

D2
A =.61
K =.77

D3
A =.01
K =.88

Values at blend pot:

+ 9v, - pot:
1= 7.31
2=7.31
3=7.00

-ground, +pot:
1=0
3=.08

Hopefully this is enough info that some one can help me. I'd really appreciate it, thanks.

[basscase]

Ok...got it fixed...I found a cold solder upon triple inspection. My own dumbass fault. Now it works perfectly. Octave switch and all. Woo hoo!!!   

[jimbob]

whrere did you find a mod for that switch? Sounds interesting. can you post it?

[basscase]

It's really simple and sounds way cool. The down 1 octave is a bit more nintendo like than the 2 octave down. I just put the wire for pin 1 in the hole previously occupied by one end of r11 and you can connect the other wire to r3 or r11 since they are connected.


Here's the details from a previous post from the forum :

Think of the 4013 as being used here like phase shift stages (oh god, I know I'm gonna regret that one.....).  With a complex phase shifter, you migh tap the phase shifted signal after 2 stages, 4 stages, 6 stages, etc., expecting more phase shift the further along you tap.  Well, in this case, the 4013 just keeps in dividing by 2.  If you tap the 4013 at pin 13, the signal has only been divided by 2 once at that point.  If you tap at pin  1, it has been divided by 2 again and is an octave further down because of that.

So, disconnect the end of R11 that goes to the chip, and install a SPDT two position toggle.  The "free" end of R11 goes to the centre lug on the switch. One of the outside lugs goes to pin 1, and the other outside lug goes to pin 13.  You do not need (and shouldn't) cut the connection between pins 1 and 13.

That's it.