True Bypass - Colorsound Supa Tonebender

[Ulrich]

As a layman, I understand the concept of True Bypass quite well.  But for me, there is always the problem to find the In and Out of the circuit.

The same problem with the Supa Tonebender I just got. (Sounds great.) There is already a DPDT switch, but just three pins are used. One is connected to the pedal in, one to the pedal out, and one to the board (obviously the circuit in or out). But how to find the other circuit connection?

Thanks
Ulrich

[MartyB]

Ulrich,

  The CS Supa Tonebender I have has made use of all the pins on the DPDT switch.   Looking at the PCB from the component side with the jacks on top,  I count eight wire connections to the board.  Starting at the top left and going clockwise : 1) gnd to out jack, 2) out tip, 3) gnd in jack, 4) DPDT center lowest pin, 5) batt+, 6) DPDT left upper, 7)DPDT center upper, 8 ) batt-.   The two right upper and lower DPDT pins are wired together.  Hope this helps.  I don't have a schem.

MartyB

[Ulrich]

MartyB,

Thanks for your reply. I just tested it, but I think, this is not a true bypass configuration. This is indicated by one pin of the DPDT is left unused. Also, my original configuration is slightly different.

There are 9 pins on the board. Starting at the top left and going clockwise, the configuration is: 1) gnd of out jack to batt-, 2) out tip, 3) in tip, 4) gnd of input jack to the board, 5) DPDT right upper row, directly connected to in tip (terminal 3), 6) batt+, 7) DPDT left upper (goes to center pin of the volume pot, the only +connection to the ciricuit), 8) DPDT center upper (goes directly to out tip), 9) batt- (goes direclty to gnd of output jack).

Here is a picture of the board (not mine, but exactly the same):

Thanks
Ulrich

[MartyB]

Ulrich,

Here's a link to a pic of mine.

Marty


http://www.freewebs.com/martyb/colorsoundsupatonebend.htm

[RickL]

The normal configuration for a spdt switch used for non-true bypass is: lug1 - input jack and input to circuit, lug2 (centre lug) - output jack, lug3 - output of circuit (probably the wiper of the volume pot).

In your case one half of the dpdt switch is not being used, it's been wired as the spdt switch above. The place that the upper right pin of your dpdt connects to the board is the input of the circuit, the output of the circuit is the centre pin of the volume pot.

With this info you should be able to rewire the existing dpdt to true bypass by simply moving a couple of wires.

[Mike Burgundy]

Marty's pic does the trick.

[Ulrich]

Thanks again very much  for the picture. This is a reissue, right? I think, my original circuit needs some modification. I talked to a friend of mine, and he will help me.

Ulrich

[MartyB]

Yes, mine is the Steve Hackett edition.  I'm not sure how they differ.  I've read that the Supa is a Big Muff Pi with one less transistor stage.

Here's Mike's schem. retrieved from search:

http://users.balpol.tudelft.nl/~Burgundy/bin/schem/supaTB02.gif

MartyB

[Mike Burgundy]

I forgot that one was still there
Traced from an original that was rather gutted, but with the generous help of all here we got it in working order again (see archives if you're interested)
The cute thing is that the second stage has all traces and pads to give it feedback clippers as well and turn this thing into something resembling a BMP.
The remark about the 22u: I reckon it's a 2u2 cap anyway
I bet that's what in yours?
The trannies are generic NPN, very similar to a BC109 I think

[Ulrich]

Hello again.

I did not see the other two postings (thanks Mike and Rick). AND I also did not realize all the time, that the input tip is not only conected to the switch, but that in that long row of metal there is also a tiny resistor. This is the input to the circuit, of course.

Sorry, quite a silly fault. A friend of mine pointed me to this connection.  I just soldered, and it works.

Regarding Big Muss vs Tonebender - the Big Muff has much less middle frequencies, which is desired or not. One needs both, I think.

Thanks all
Ulrich