Changing Switches-- Please help! (newbie)

[otokomae]

I'm changing from a simple 2-pronged, BOSS switch to a DPDT switch, but I can't seem to get it right!  Everything else is already wired (it's a BOSS pedal), and I tested it before taking the old BOSS switch off, so it must be the way I'm wiring the new switch.  There are only 2 wires that were used with the old switch, 1 coming off the INPUT and another taht goes into the PCB.  I'm changing to an Alpha 107-SF12020-L DPDT switch from Small Bear.  One side of the switch says "Alpha" and numbers the prongs "1-2-3";  the other side just has a capital "L" on it.  Does it matter which side I use?  Do I need more wires, or can I do this with just the 2 that were on the original BOSS switch?  Do I use the middle prong, or just the 2 outside ones?  If anyone can help me with this I would be very greatful (I'm getting tired of soldering and desoldering!)  Thanks!!!

[travissk]

Just to clarify - the Boss pedals use electronic switching, meaning a couple of the transistors on the board have a part in switching the signal, along with that small switch. The DPDT switch you are installing is a purely mechanical switch, and you need to take the appropriate transistors out of the circuit (and short circuit one of them).

You will also need to do some rewiring with the LED.

Have you done these things? It's the first thing to check before we troubleshoot the connections.

[Mike Burgundy]

Trav: Reading the story, I don't think he has taken out the FET switching (using the two original switch wires...)
Otokomae, Trav is right. BOSS pedals use FET switching like the TubeScreamer (may be easier to find) does as well.
Have a look here:
http://www.mif.pg.gda.pl/homepages/tom/files/DS-2.gif
Right-hand bottom corner is the switching arrangement. Whenever the switch is pushed, it makes contact with mass, pulls the flipflop (which is what that little two-tranny circuit is called) control lines to ground which in turn *reverses the flipflop outputs*. One is  at "1" (meaning 9V in this case) one at "0" (0V, or ground). Everytime you hit the switch, the output that was 1 becomes 0, and the output that was 0 becomes 1.
Okay, these signals are used to work Q3, Q4 and Q21 as switches. They alter between very low resistance (the FET is "on") and very high resistance (the FET is "off") depending on wether they see a "1" or "0" at their gate. One byproduct of this circuitry is that it always resets to the same state when power is taken away (everytime you unplug the input), and that state is bypass, while we want a permanent ON.
What we need to do is tell these three FETs (and there might be more in your pedal)  that they always have either a ) or 1 on their gates (essentially we hook them up - perhaps via a resistor - to either +9V or ground). One could also completely remove them and bypass the connections - whatever takes your fancy.  You can then use a DPDT switch for true bypass (beginners section, I think), or a 3PDT for TrueBypass with a LED, or a DPDT with the Millenium circuit for TB with LED....
This does obviuosly take some knowledge on what's what on your PCB. Don't get scared - we might be able to pull this off if you give us more info, perhaps some pics, but don't start cutting unless you're sure
hih

[otokomae]

wow...
OK, I just want to start off by saying that the people on this forum really are the best.  Was it just luck or did you somehow know that I'm using a DS-2 (I don't think too many people do a lot of mods on these)?
Anyway, it is in fact a DS-2 (the schematic you used for your example) that I'm trying to change the switch for.  Give me a second to go read what's been posted again, and compare the suggestions with the schematic, and if it doesn't suddenly come to me, then be right back (ith another question probably).

[otokomae]

OK, I think I'm strting to get this.  First off, I need 2 new wires connecting the INPUT directly to the OUTPUT, using the 2 middle prongs on the DPDT switch, right?

[otokomae]

Also, I've just gotten an email from Steve at Small Bear, saying that switching this to true-bypass is difficult, but totally do-able, and some other threads about people switching their BOSS pedals to true-bypass seem to make it sound worthwhile.  So, here's a question:
One thing that is making this look more complicated is the stupid REMOTE for the Turbo mode, which is pretty much useless  and which I never use (the remote, I mean).  But it goes between the Input and the switch, for some reason.  Can I simply remove the REMOTE part altogether, is that making things even more complicated?
Also, it looks like there is more than one way to go about this (changing to true bypass), and I'm really not sure which is the best/ easiest way to do it. Can anyone give me any suggestions??  I really want to have a pretty exact plan before I start desoldering stuff.  Thanks!!!

Oh, once again, here's the schematic:  http://www.mif.pg.gda.pl/homepages/tom/files/DS-2.gif

I've been staring at it all night, and it just seems to get uglier...

[travissk]

Disclaimer: Anyone with real experience in this stuff (I've never done it), please feel free to correct my post with extreme prejudice . Now on to the post:

///////

I'm sure I'm going to mess this up if I go into too much detail, but essentially here is what I see in the circuit:

Look to the bottom-right corner. You see the "Effect On/Off" switch. That is the "momentary" switch that is currently in your pedal.

Now, to the left of that is an area, a little "mini-circuit" if you will, that is the "flip-flop" that stores the value of the switch. As I mentioned earlier, your DPDT is purely mechanical. It's like a light switch, where you flip the switch up and it stays up, making a connection. Then you flip it down and it stays down, breaking that connection.

The boss switch is like a button. You press it, and the lights go on. You press it again, and they go off. The flip-flop-esque circuit is essentially in charge of saying "OK, the button has been pressed and the effect is on. Let's turn it off". Or: "OK,  the button is being pressed and the effect is off. Let's get ready to ROCK!". That's the quick and dirty explanation. I hope my Electrical Engineering professors don't read this forum.

Now there are two wires that go up from here, way up to the top right of the schematic. One goes to parts numbered D4 and Q4, another to D3 and Q3.

Again skipping about a year of EE classes, one thing you can use transistors for is a switch. Q4 and Q3 are switches that will pass the signal depending on what comes from those two wires that came up from the bottom area of the circuit.

If you look to the left connection of Q3, you see just a few parts between it and the input signal. This is the clean signal path

If you look to the left connection of Q4, you see... a ton of stuff. It goes down to the VR BOARD and through lots of other parts before winding back up to the input signal. This is the dirty signal path.

So when the effect is off, your signal will travel through the top of the circuit, through Q3, and then out to the output.

When the effect is on, it gets distorted through that mess at the bottom, then goes through Q4 and out.

Sorry if that explanation was only slightly clearer than mud. The key is, aside from that circuit at the bottom, Q3, and Q4, you don't need to worry about the rest of the circuit at all.
-----

Now that you know what parts are involved in the switching, here's a very quick rundown on what you need to do:

-If you're concerned about power requirements, you can cut off power to the bottom part of the circuit. That's not essential.

-Since your switching is mechanical, look at a "How to wire a DPDT switch" diagram. I'm sure we have tons around here.

-When you have a true bypassed effect, your effect is "always on" and the switch dictates whether you use the clean or dirty signal, as opposed to parts like Q3 and Q4.

-Therefore, we want to block the signal coming through Q3 (the clean one). Just desolder and remove the transistor, leaving the path there as an open circuit.

-We want the dirty signal to always be used. Therefore, remove Q4 and put a wire between the left and right terminals. The transistor has three terminals, one on the left, one on the right, and one coming down out of the center. Make sure you join the left and right ones with a wire.

Now that you don't have that flip-flop circuit at the bottom, the LED needs to be handled differently. If you have a 3PDT switch on hand, it makes it easy to add an LED, otherwise you will need to make a small circuit called the "Millineum Bypass 2." Run a quick search for that. It is very easy and only uses a few parts.

From there, you just need to follow the directions for wiring up the DPDT as if you had an effect that you created.

That's "all" there is to it  
----

Finally, I don't think the Remote jack connects to the input at all. That "o" (white circle with black outline) means there's no connection there where two lines cross, while a black circle means that there is a connection between the two wires. You need not concern yourself with it; unless you want it out of your life forever (in which case, cut the wires or ignore it), it's not going to get in your way for bypassing.

Again, sorry if that was confusing; I (and presumably everyone else here) will try to answer all your questions. Good luck, and have fun!

[AL]

See if this helps. Robert Keeley article about modding a TS-9 for true bypass. Maybe it will shed some light?

http://www.musicianshotline.com/archive/monthly/pedal_power/0704.htm

AL

[otokomae]

Well, this is great everybody!  I'm still figurung out the "Millennium Bypass 2" circuit (how to build it, that is), but once I get that, I think I'm going to give this a try.  I've already found a couple of articles on the Millennium circuit, but if anyone knows one that is just fantastic or that deals specifically with BOSS pedals, please post it here!  Also, if anyone has anything to add to how I should go about making the pedal True-Bypass, or if there's anyone out there who has done this to a BOSS pedal, please also post that here if possible.  Thanks again!!!  Oh, and if anyone needs or wants to see a schematic of the pedal, it's a BOSS DS-2 that I'm working with, and the schematic has been posted in this thread at least 3 or 4 times, and I might even post it again later if I keep having trouble with it.  Thanks everyone!!!!

[Mike Burgundy]

Yes, I'm psychic (did you say "sidekick"?)
hah.
Ignore the entire turbo circuit for now, it has nothing to do with the switching. If you don't use the remote, it has no influence on anything  Don't get confused by the outlines: they depict what is on which (of the two) pcb's but don't connect anything. The remote only connects to R27.
Do some reading-up, and after that we'll see if we can figure out which parts to take out.
Mind you - it might be rather tough figuring out what's what, since theat board is loaded with similar looking trannies...
Do you have a DMM?

[travissk]

I mentioned what I thought needed to be changed in my post up above, but if anyone wants to check my guess, here's the bare-bones version.

-Open-circuit Q3 (remove the transistor)
-Short-circuit source and drain of Q4 (lift the gate connection which goes to the diode then down to the flip-flop)
-Change the LED to use Mill. Bypass 2 or use a 3PDT.