Need help with SD-2 Clickless true bypass

[gravityman]

Hey guys, I'm having difficulty figuring out how to install my true bypass clickless module into my SD-2. These modules have a (+) and (-) terminal for the LED. You'd usually disconnect both wires from the board to the LED and hook it up to the module but in this sd-2 has a bicolor LED. My issue is, it seems that on the anode side of the Bicolor LED (both colors) there is a transistor (?) after the CLR. I was thinking, If I were to short (on both sides) and just hook it up the the (+) LED on the relay bypass board, wouldn't that just short out the sub circuit involved with switch the pedal from LEAD to crunch?   


I'm sure somewhere along the circuit is a point where the connections leading to both anodes of the bicolor LED meet BEFORE, the switch. I just need to find that, i think?






Please advise! I emailed Mammoth as well with no reply yet. I was wondering if anyone here could drop some insight.

[PRR]

> my true bypass clickless module

Schematic?

[gravityman]

I attached a schematic of the SD-2! If it won;t load, here is the link https://postimg.org/image/8cx8yp5c3v/

[wordstep]

I think you still do not know how the boss switch system working. Please google a bit.

And you pick the wrong pedal to do your mod. SD2 is too complicated.

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If I need to do it, I will short Q8/Q11/Q15/Q13-- (or remove these 4 transistor, and replace them with wire in the signal line)

Remove Q12/ Q9---the old bypass
Remove  Q4/Q5----the old LED control

In the point before C22, use SW1b to switch the 2 channels, Use SW1a to switch Green LED---show which channel is used.
(I have doubt here, SW1a/SW1b ---MODE-SW-------- the mode switch is an IC)

Use Red LED to connect to your module led lines.-------show bypass or not.

Use the BOSS switch connect to your module switch lines.
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I believe this is too much for you. But for SD2, you need to do this to keep the two channels.
Also,you need a remote switch for switching channels.

In short, do not mod SD2. Find another BOSS pedal.

[wordstep]

OK, I have another idea.

Use the BOSS Flip-Flop to switch 2 channels ---- and the BOSS Flip-Flop control by remote switch.

Use the BOSS old switch to control the true bypass module.

Two LEDs, one for true bypass. one for which channel is ON.
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This idea is better. Do not need to deal with the MODE-SW.
It can be done. Not easy at all.

Same, do not mod SD2.

[Fancy Lime]

Why so complicated? You can make it true bypass without messing with the board itself at all. However, it only works (easily) under certain conditions. The method below will circumvent the whole circuit board when the pedal is off but will switch the whole board, including the input and output buffers, in when the pedal is on. For pedals that were designed with buffers it often a good idea to leave them in when the pedal is on. in case of the SD-2 it will not make a big difference but for some circuits it will. I'm sure others have used the method below, maybe someone knows a tutorial.

0) Check if the unmodded pedal and the switching circuit are consistently in on or off mode when powering up.
1) If they both always start in the same state, no matter what state they were in when you last disconnected the power, you are in luck. If they do not, the following method won't work without some extra fuss. If both circuits not only start in the same state as last time but also the same state as the other circuit (on or off, does not matter as long as it's the same), then you can hook the connections for the momentary switch of both boards up to the same momentary switch (the one already in the pedal). If the main board always starts "on" and the switcher always starts "off", connect only the switchboard to the footswitch and disconnect the main board switch. If, on the other hand the main board starts "off" and the switch "on" things get a bit more complicated and this method will also not work as easily 8lets worry about that only if we have to.
1) Disconnect the main board from the input and output jacks.
2) Connect the main board and the in and out jacks to the bypass board as per the manufacturers instructions (if I did get that right that you bought a ready-to-install unit from Mammoth).
3) Do something with the LEDs. However, to help you with that (which may or may not be the problem in your original post, cannot quite make it out) we reall do need the schematic of the switch board.

And please describe in a little more detail what exactly you want to do, I am slightly confused.

And of course there is also the method I always suggest in these cases: Do not mod a perfectly well-functioning pedal but use your switch board to build a looper. Much more versatile, easier and no chance of messing up an expensive pedal, which you may at some point want to sell again.

Hope that helps a little,
Andy

[gravityman]

Thanks for all the input guys, and I'm sorry if what I said was confusing , but this is basically my situation. I've installed these mammoth true bypass modules in many other boss and ibanez pedals for my friends. I'm the one that knows how to solder and do some circuit analysis cause I took few electives in my engineering degree so I'm just helping them out. Yes, I personally agree that it makes more sense to use a looper, but Im just trying to help out a buddy as I've already done this for his other boss pedals.

My relay bypass is by mammoth electronics, previously owned by Jack Deville, so the exact schematic isn't up for anyone to see. 

Here's what it looks like:



The L terminal (encircled in red) is where the anode of the LED should go (in this case, a bicolor LED)


Here's a schematic of a similar circuit, but uses an photofet. Hopefully this will help.





In the instruction pdf supplied with the clickless bypass says to disconnect the wires leading to the anode and cathode of the pedal's stock LED indicator, and hook those up to
the terminals on the bypass. My issue is, the boss SD2 uses a bicolor LED to indicate whether the pedal is on, and what CHANNEL it's using. So I'm not sure where to disconnect the connection leading to
the anodes of the Bicolor LED since they both seem to be wired to subcircuits what looks like transistors, and eventually the rotary switch for the mode selections:

LED section is encircled in orange, bypass circuit in red.





Sorry if its confusing. I've done this before, I'm just unsure with this one SD-2. I just want to now if its possible because my buddy is really keen on it. 

[gravityman]

Why so complicated? You can make it true bypass without messing with the board itself at all. However, it only works (easily) under certain conditions. The method below will circumvent the whole circuit board when the pedal is off but will switch the whole board, including the input and output buffers, in when the pedal is on. For pedals that were designed with buffers it often a good idea to leave them in when the pedal is on. in case of the SD-2 it will not make a big difference but for some circuits it will. I'm sure others have used the method below, maybe someone knows a tutorial.

0) Check if the unmodded pedal and the switching circuit are consistently in on or off mode when powering up.
1) If they both always start in the same state, no matter what state they were in when you last disconnected the power, you are in luck. If they do not, the following method won't work without some extra fuss. If both circuits not only start in the same state as last time but also the same state as the other circuit (on or off, does not matter as long as it's the same), then you can hook the connections for the momentary switch of both boards up to the same momentary switch (the one already in the pedal). If the main board always starts "on" and the switcher always starts "off", connect only the switchboard to the footswitch and disconnect the main board switch. If, on the other hand the main board starts "off" and the switch "on" things get a bit more complicated and this method will also not work as easily 8lets worry about that only if we have to.
1) Disconnect the main board from the input and output jacks.
2) Connect the main board and the in and out jacks to the bypass board as per the manufacturers instructions (if I did get that right that you bought a ready-to-install unit from Mammoth).
3) Do something with the LEDs. However, to help you with that (which may or may not be the problem in your original post, cannot quite make it out) we reall do need the schematic of the switch board.

And please describe in a little more detail what exactly you want to do, I am slightly confused.

And of course there is also the method I always suggest in these cases: Do not mod a perfectly well-functioning pedal but use your switch board to build a looper. Much more versatile, easier and no chance of messing up an expensive pedal, which you may at some point want to sell again.

Hope that helps a little,
Andy

Thanks for the help! Yeah I have on the mammoth ones. There's a part in the instructions where you have to remove a resistor from the boss bypass circuit to keep the pedal always on, which is what I did on the other boss pedals i true bypassed.

My only issue is, I'm confused on how to go about the step for the LED. It says to disconnect the led on both the positive and negative sides. The Bicolor LED has a common cathode (so thats easy), but on the anode side, they come from different points/connections, which is related to the mode switching on the pedal. My problem is finding the point along that path where those paths unite and get power from. That's where i "think" i should wire the + LED terminal of the bypass but correct me if im wrong.
I know how to wire every other part: the input,output,send,return,power, switch.. Its just the positive side of the LED that I can't seemt to get past. 

[Fancy Lime]

Ahh, now I see. Thanks for the clarification.

Why not keep using the LED that's in there just the way it is? Use the new bypass as a bypass but keep switching the LED's with the existing switch and flip-flop circuit. Seems like less hassle than re-routing the channel switch as well.

Just out of curiosity: How do you intend to connect the new bypass? Will it go between the main board terminals as is and the jacks or will it take the buffers out of the signal path?

Andy

[gravityman]

Ahh, now I see. Thanks for the clarification.

Why not keep using the LED that's in there just the way it is? Use the new bypass as a bypass but keep switching the LED's with the existing switch and flip-flop circuit. Seems like less hassle than re-routing the channel switch as well.

Just out of curiosity: How do you intend to connect the new bypass? Will it go between the main board terminals as is and the jacks or will it take the buffers out of the signal path?

Andy

Based on my analysis, yeah it goes between the main board and the jacks just like how a 3PDT would work. Its got terminals for the input, output, send,return,ground,+ 9v etc...It's really just hooking it up the the anode of the LED (which has two since bicolor)

[wordstep]

I just check the SD2 manual, compare to a regular BOSS pedal, in SD2, the push button has special function.

Depends on the switch setting:
1_ switch between Crunch and Lead only, pedal always on
2_ pedal on Lead channel only, switch Lead channel ON/OFF
3_ Pedal on Crunch channel, switch Crunch channel ON/OFF  ------use a remote switch to switch between Crunch and Lead

Assume you set the switch to position 2 or 3, and you use off board wiring.
Just use the RED LED part of the bicolor LED for your module,
cut between R10 and Q5, connect  your module led + line to R10, connect the module LED  - wires to pedal GND
(Now you do not care It is a bicolor LED or 2 separate LEDs)

Maybe need to adjust R10 value. (It is better to use a meter for the + LED line here)

So Red led indicates pedal ON/OFF, Green LED indicate Crunch is ON
No green LED, the pedal is in Lead Channel.

(Also, connect Q9 input to GND, GND the flip-flop?)

[PRR]

> I attached a schematic of the SD-2!

I was probbaly curious about your "my true bypass clickless module".

> the exact schematic isn't up for anyone

Well, OK....

> the instruction pdf supplied with the clickless bypass

Maybe seeing that would be helpful? For folks who do not keep up with Mammouth's offerings?

{sigh} LINK. Documentation, such as it is, under "Installation".

I think Andy and wordstep are already on the case.

[wordstep]

True bypass module off board wiring. The BOSS switch is used by the module.

So in SD2, no switch to change the flip-flop, since the flip-flop is an unstable circuit.
When power in on, you can not confirm the flip-flop is "High" or "Low".
(Maybe in a particular pedal, High" or "Low" of flip-flop can be confirm. Not every SD2.)

In SD2, have to do more mod in the signal system.

Case 1: User do not use remote latch switch (in rotate switch position 3)
           when use Lead channel, put rotate switch to Position 2--------mod to make sure Lead channel is ON.
           When use Crunch Channel, put rotate switch to Position 3-----mod to make sure Crunch channel is ON.
(Since the original design is when crunch is ON, the LEAD is off, we can not just set the flip-flop to just HIGH or Just LOW)

Case 2: User use a remote foot latch switch to switch crunch/Lead. Rotate switch is only set to Position 3
           mod to make sure when Rotate switch is only set to Position 3, Channel is ON---not bypass.

Case 3: some times want case 1, some times want case 2

If want to use LEAD/Crunch of the SD2, have to do in board mod. And Case 2 should be the easiest way.
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My easy way----might be too complicated to others.--------need a momentary switch connect to remote 1/4 jack
Put Rotate switch to position 1-----pedal is always on the flip/flop is just switch Crunch/Lead.

Remove any wires from the remote jack, connect a momentary switch to the remote jack.
Use this switch to replace the BOSS PUSH plastic switch.

And the BOSS PUSH plastic switch connect to the true bypass module for true bypass ON/OFF.
LED ...