tone bone classic true bypass wiring

All frequent questions on switching: true or not true bypass, transistor-based or mechanical.
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copachino
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Post by copachino »

hi, does anyone has any diagram for the tonebone clasic for a 3pdt wiring switch??, i need to change the switch but i cant find the ins and outs of the fx,.. any help??

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dwmorrin
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Post by dwmorrin »

I just drew this while looking at the schematic.
It looks like you've got a DPDT that just switches the output on one pole, and the LED on the other.
This may be more trouble than it's worth, as the input doesn't appear to "load" much, but it's your call...
Both the input and output connections require quite a bit of work to get to "true bypass" status.

First - understanding your current DPDT. One pole is audio, the other is LED.
The audio pole is connected:
BYPASS side = input jack direct connection
COMMON = 2M2 resistor that goes through a 330n cap, then sees output jack and another 2M2 resistor
FX side = 2k2 resistor that is attached to the LEVEL wiper.
The LED pole is connected:
BYPASS side = CCW lug of drive pot
COMMON = CW lug of drive pot
FX side = 10k resistor
I may have the BYPASS/FX connections reversed for the LED. Just figure out how it is working now using my hints, and move it to the 3PDT.

Next, use the image as a reference, and start breaking connections.
I don't know how the pedal connects input jack to circuit board, but this connection has to be broken.
Run a wire from the input jack (now connected to nothing) to the 3PDT. Use a "common" terminal.
Run the FX side of the input pole back to where you broke the connection. The old BYPASS connection may work for this, but I'd have to see the insides to confirm that.

The output is a bit more confusing.
Take the old FX out (connected to 2k2 resistor) and the old output jack connection (2M2 and 330n cap) and splice these together.
Now break the output jack's connection just like with the input, and run the bare output jack to another "common" terminal on the 3PDT.
Run wire from the broken "old" output jack connection to the FX side of the output pole.
Tie the BYPASS sides of both the input and output poles together.

Hope this helps! And I still say this is way too much work for what will probably be a very small, if undetectable, change in tone.

Image

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