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Boss JFET

Started by spoontex, June 30, 2015, 07:04:36 AM

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spoontex

Hello,

anyone can help me to found the input and output jfet buffers from these pedals? I want it convert to truebypass and I would remove these transistors.

Boss BD-2
Boss CS-3

Thanks!!

GibsonGM

#1
Psst!  Welcome to the forum...can you post the schematics for them so ppl don't have to go hunt them down?  ;) 

You'll have an answer for sure, I think Boss was pretty consistent so just check back once in a while.

Meantime read this:  http://www.geofex.com/Article_Folders/bosstech.pdf
  • SUPPORTER
MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

JerS

Check out the instructions for adding clickless true bypass from Mammoth Electronics - they tell you what you need to do to defeat the fet flip flop circuit in Boss Pedals. Here is the link: http://www.mammothelectronics.com/v/vspfiles/assets/images/clicklesstruebypasscatalog.allsections.interactive.2013-1.pdf

I would think you could use this to help guide you in converting to true bypass.


spoontex

What you mean?

removing this resistor it's enough to disable the buffer?

I understand that removing this resistor the effect will stay alway on, but through the in/out buffers anyway.... no?

Boss BD-2 : http://www.freeinfosociety.com/electronics/schemview.php?id=116
Boss CS-3 : http://i2.wp.com/pdfelectronics.com/wp-content/gallery/pedal-mods/boss-cs-3-schematic.jpg?

I see this post: http://www.diystompboxes.com/smfforum/index.php?topic=61035.0

And I want make the same with the BD-2 and CS-3. If removing one resistor it's enough, because they don't remove it and let the transistor on the board?!?!

thanks.

GibsonGM

Is there a reason you don't want the buffers?  They really don't affect much, if anything at all.  You are correct, that way the buffer is still in the circuit.  You'll have to read more to find out if there is an easy way to jumper the buffer.

But, so you know...look for the last "Q" before the output. That is your buffer.  The switching circuit is a flip-flop, so follow its right hand output.
  • SUPPORTER
MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

R.G.

Anybody ever hear of Blind Urge to Mod Syndrome (BUMS).    :icon_lol:

(1) true bypass isn't the panacea that it's promoted as; there are certain very special instances where it's a good idea, but these situations don't happen much any more in today's world
(2) there are simpler ways to true bypass a Boss pedal that do not involve as much surgery; notably, you can simply use the existing flipflop circuit to run a relay inside the box; see the Technology of Boss and Ibanez Bypasses http://geofex.com/Article_Folders/bosstech.pdf at geofex.com http://www.geofex.com.

In fact, reading all of geofex.com would be a GREAT idea for any beginner.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.