Help with Octave on Tone Machine/Ultimate Octave.

[bjk5959]

Alright, so I've been fighting with the octave on my Ultimate Octave build for a while now.  The fuzz works great, and sounds just as it should, but when I kick in the octave effect, there is no audible octave.  The signal thins out and compresses a bit, and also quiets down a little.  It sounds like it should be working, but it just doesn't come through at all.  I've played it on the neck pickup, 12th fret, tone rolled off, etc... and still nothing.  I matched the diodes (.445 and .448 on my DMM)--D2 and D3 according to the aronnelson vero layout.  I've double checked my transistor voltages, and they correlate well with the voltages listed by GGG here:

http://www.generalguitargadgets.com/pdf/ggg_ftm_instruct.pdf

Vero layout here minus UO mods:

http://www.aronnelson.com/gallery/main.php/v/Toneys-Album/Foxxv4_001.png.html?g2_imageViewsIndex=1

UO schem:

http://i199.photobucket.com/albums/aa115/jimi_026/Ultoct.gif

I used 2N5172 for transistors.

Any ideas?

[bjk5959]

Any clues?  I'm really at a loss here.  Anything more I can give for clues?  I've checked components, placement, etc...NO IDEA

[tcobretti]

Honestly, what you need to do is follow the instructions in this thread.

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Then let us know the results here.

[bjk5959]

Sorry about that.  Hopefully this helps:

1.  Fulltone Ultimate Octave

2.  Schem:  http://i199.photobucket.com/albums/aa115/jimi_026/Ultoct.gif
     Vero:  Layout minus mods: http://www.aronnelson.com/gallery/main.php/v/Toneys-Album/Foxxv4_001.png.html?g2_imageViewsIndex=1
     Wiring:    http://www.generalguitargadgets.com/pdf/ggg_ftm_lo_2fsw.pdf (DPDT used instead of 3PDT for octave switch)

3. & 4.   Mods:  (going off of vero layout, converting tone machine to ultimate octave)
      Omitted C4 from build
      Changed C2 and C6 to .047 uF
      Added 10k resistor before fuzz pot
      100k pots
      100k resistor between lugs 2 and three of fuzz pot
      Tone cap switched to .015 uF

5.  Ground neg schem--ground neg circuit

6.  The fuzz works great, and sounds just as it should, but when I kick in the octave effect, there is no audible octave.  The signal thins out and compresses a bit, and also quiets down a little.  It sounds like it should be working, but it just doesn't come through at all.

Voltages:

Q1

E 0.14
B 0.70
C 2.03

Q2

E 1.19
B 1.77
C 7.71

Q3

E 0.25
B 0.83
C 6.77

Q4

E 0.22
B 0.77
C 8.04

D1

A  0.00
K  9.46

D2

Octave on and off

A 0.00
K 0.00

D3

Octave On

A 7.86 
K 7.72

Octave Off

A  4.75
K  4.64

D4

A 0.00
K 0.00

D5

A 0.00
K 0.00

Power  9.46
Ground 0.00

So does this mean D2 isn't getting power?

[tcobretti]

On that layout, which diode corresponds to D2 in your description?

That 0 volts means the signal coming off the transistor is being pulled to ground somewhere.  The change in sound does make me a bit suspicious of the switch's wiring, because I don't think the sound should change if it is already grounded out.  Are you sure the switch is running to the correct trace on the vero board?

If it's D3 on the layout, I'd check very carefully for solder bridges to ground, since it straddles the ground strip.  You could maybe use a continuity tester to help figure out exactly which trace (above or below the ground trace) is going to ground.

Are the diodes oriented correctly?

The main thing here is that now you know the problem is around that diode, so work your way out from there looking for incorrect components, incorrect orientation, or sloppy soldering.  This kind of stuff is why I started etching circuit boards. 19 times out of 20 a PCB will fire up and work perfectly the first time you put power to it.

[bjk5959]

D2 corresponds to the vero layout:  http://www.aronnelson.com/gallery/main.php/v/Toneys-Album/Foxxv4_001.png.html?g2_imageViewsIndex=1

And I think you're right--there probably isn't a change when the octave is switched in.  It seemed like it did a while ago when I first fired the circuit up.

I'll have some time to look at the other stuff tomorrow.  I'll report my findings then.

Thanks for the help!