I could kill you

Vintage effects can sometimes add unwanted signal loss to your sound and a simple mod can fix this. A True-Bypass switch’s purpose, put simply, routes your guitars signal only through the connections of the switch, leaving the effect’s circuit completely disconnected. An easy way to picture this is when you switch your petal off, it’s as if the the input/output are wired together (like with a coupler). You can find a more in depth explanation here. This method should apply to most effects pedals, for information on how to wire a wah with a 3DPT check out Stewmac, also a good place to pick up a high quality 3PDT switch. I used a Electro Harmonix brand switch I got for under ten dollars on eBay, great quality.

***NOTE: The addition of this switch to a MXR Distortion+ makes the 9v battery no longer fit in the case properly. I haven’t solved this issue at the point of this writing, so if you can (or have) found a better way to mount the battery let me know. If you will not be adding an LED to your pedal, you may want to use a DPDT switch instead. (check the link at the end for a how to) DPDT switches are slimmer than a 3DPT switch and you should have no problem mounting the battery. If you use the DPDT switch, it will wire the same as this example because the 3DPT adds only the other row of posts useful for adding a status LED. (Keep in mind this may devalue your vintage effect and you risk the small possibility of damaging your pedal.)

What you’ll need:

• Soldering iron and solder (need to learn how to solder? go here)
• Philips screwdriver
• 3DPT switch
• Some yellow color wire (same gauge as the other wires in the pedal)
• Wire snips and/or stripper

First step:

Take the back off of your D+ pedal, warm up your soldering iron and de-solder/remove the old switch. Once you have that out, install the new 3DPT switch.

Second Step:

Next you need to unsolder the yellow cable from the input tip (labeled A in the pic below) and the other end that is connected to the circuit board (labeled B below) These will need to be wired to different posts on the switch. The yellow wire from the circuit board will need to be longer, this is where you will need some new wire. Make sure the new wire can reach from the circuit to the switch and re-solder it to the circuit board. Then re-solder the input tip yellow wire.

Third step:

Now you can begin to wire the posts of the switch. Here is a diagram for what posts you want to use.

Position one and two will be the on/off functions of the switch when it is engaged. For this example posts 7,8,9 will not be used, but they can be used to add a LED for on/off status (I will revisit this and show you how to do that at a later update). Refer back to this diagram for wiring posts.

First tin all your wires and all the posts we will be using on the switch.

We will start with wiring the yellow wires. You should have two yellow wires, (from step two) one connected to the circuit board, and one connected to the tip of the Input. Solder the yellow wire from the input to post number number 5 (shown on the diagram above). Then solder the new longer yellow wire from the circuit board to post number 6.

Fourth Step:

Next you will need to wire a jumper from post number 1 to post number 4. Use a piece of scrap wire to make the connection.

Fith Step:

Finally there should now only be two wires left to connect, the blue and brown wire. Solder the blue wire to post number 2. Now solder the brown wire to post number 3.

Your new switch is now wired, plug it in and check it out. You should now have improved performance and more than likely a higher quality switch that can hold up to more road abuse.

Trouble shooting:

If for some reason your unit doesn’t work when you turn it on, go back and check your signal flow. Make sure the wires are attached to the correct posts and check for cold solder joints.

If your wires were different colors than mine their connections are as follow:

• Brown is connected to the middle terminal of the output pot.
• Blue is connected to the tip of the output jack.

Useful links:

I found some more useful information about modding the MXR D+ online that I will be doing a tutorial for at a later time, so check back. Here are some links;

Nice tutorial on wiring a DPDT switch on a 1980 D+ - Link here

Premier Guitar shows you some D+ mods - Link here

Distortion Plus schematic - Link here

At a later time I will post the mods from the Premier guitar link and post a tutorial with switches to bypass mods so you can still have the original pedal sound as well as the modded sounds. Will also show you how to add the LED (witch is very simple).
Have a link to some D+ mods? Comments? Something you would have done instead? Let us know in the comments.

Tags: 3DPT, Guitar, MXR, mxr distortion plus

This entry was posted on Sunday, January 3rd, 2010 at 5:47 pm and is filed under Guitar. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.