OD bleeding thru on a Boss SD1

[cmat]

Does anyone know how to stop the drive from bleeding through on a Boss SD1 when bypassed?   Changing R2 helps but doesnt fix it any help or ideas would be greatly appreciated.  Thanks!

[vanhansen]

This has come up lots and lots of times.  Many things have been tried with no 100% sure way to fix it other than possibly a better layout.

These are just a couple of topics I found on this.
http://diystompboxes.com/sboxforum/viewtopic.php?t=35935
http://diystompboxes.com/sboxforum/viewtopic.php?t=22748
http://diystompboxes.com/sboxforum/viewtopic.php?t=23903

[Strat Cat]

There are 2 things you can do to fix this problem. One is to convert it to true bypass. You can do that by using it with a looper bypass pedal or adding a true bypass relay type circuit like the one posted here on the Forum a few days ago. The other way is to place a buffer in front of the SD-1. Sending the pedal a low output impedance signal from your guitar seems to clear up the leaking. At least it has with amps that I have tried it with. Those amps included a JCM 800, Sovtek MIG 50, a Carr Rambler and an AX-84 High Octane that I built.

[cmat]

Thanks for the response's!!   I tried replacing R2 with a 620K and I have tried putting a 1K and a jumper in place of R11 and R14 and the noise is still there.  What jfet would you try?  Any other ideas besides true bypass?  Thanks!!

[marduk]

NEW BETTER BYPASS! We have improved the BOSS switching making it even closer to true-bypass! In stock form these units may suffer a bit of bleed through when off if the level and gain are set very high. No longer! We now have the best sound pedal both on and OFF!

That's on his SD-1 mod page. No idea what he did; it could even just be the same R2 trick for all I know.

[cmat]

Thanks for that.  Any ideas from anyone?  I will try anything.  I know thier is a solution and I think it can be figured out on here.  I seen someone wrote changing the 2sk30's and the 2sc1815's would fix it.  What would you put in thier place?  If I dont figure this out I am going to go insane!!  I have spent way to much time on this and I have got nowhere.  We need to figure this out.  The SD1 modified sounds great and is a keeper if it wasnt for that bleed through!

[shredgd]

Hi,

the ultimate (and easy, as well) solution to this problem is in the following thread:

http://diystompboxes.com/sboxforum/viewtopic.php?t=23903

You can also jump the reading and perform this mod by analogguru:

http://forum.musikding.de/attachements/Boss_SD-1_mod_c.gif

It works 100%!!

[cmat]

Thanks alot guys!  I will try this immediatly and let you know if it works for me!

[cmat]

IT WORKS!!!!!       No more bleeding!!       5min and my sanity is back!  You guys are awesome!!  I really appreciate the help!!

[JimmyJ]

NEW BETTER BYPASS! We have improved the BOSS switching making it even closer to true-bypass! In stock form these units may suffer a bit of bleed through when off if the level and gain are set very high. No longer! We now have the best sound pedal both on and OFF!

That's on his SD-1 mod page. No idea what he did; it could even just be the same R2 trick for all I know.

He copied analogguru's mod and made it his own. He said on Harmony Central that he used a FET and Diode when someone asked about doing it himself.

[tjburton]

Does anybody have a pic of this mod? Did you do it on top of the board or on the bottom?

Help...

Thanks

[tjburton]

bump

[vanhansen]

I haven't done this to mine yet but it doesn't matter where the parts are, component or solder side, as long as it all fits back in the enclosure and works.  Heck, you could even but the additional parts on a small piece of perf with their connections and then run wires from it to the SD-1 PCB.

[gulliver]

I'm trying to search this and finding nothing more than broken links and shots in the dark.

Anyone have the final answer on this one??? 

[stumper1]

The Analog guru mod works.  For SURE.  You should be able to find it with the search function.  If not I'll try to post it.

[rockgardenlove]

http://www.diystompboxes.com/smfforum/index.php?topic=23903

Thats a good link.

[gulliver]

Okay, the link works, but I'm so exhausted from looking for an answer to this I cannot for the life of me glean and answer.

I'm a firm believer that you can find an answer to any question within the proper forum ... so I look to the forum gods, please post the real solution to the SD-1 bleed-through problem. Please.

[stumper1]

From the 3rd page of the link above.....

You need an SK30A jfet, a 0.1u (=100n) cap and a 1n4148 diode.
Obviously, you have to solder your new components to the top side of the board, because you won't be able to close your pedal anymore if you work on the traces side...!
Watching the front (the flat side) of the jfet, the three legs pointing downwards are named (from left to right) S, G and D (Source, Gate and Drain, respectively).
Yuo have to solder S to D4's cathode (the side with the black ring), G to your new 1n4148's anode (the side without the black ring) and D to one side of the cap.
The other side of the cap must be soldered to the point where R5 and R6 "look each other" (they are connected together at that side, so it doesn't matter if you solder to R5's or R6's leg, choose one!).
Solder the cathode (again, the side with the black ring) of your new 1n4148 to the cathode of D8.
Done!

It works.  I used a J201 for the fet - pay attention to pinout.  Good luck.

[gulliver]

Great, thanks a million!

I have these mouser part numbers:
Cap= 0.1 UF Metal Film [5989-250V.1-F]
Diode = 1N4148 [512-1N4148]

But can't find the SK30A. I searched under "SK30 jfet"  and found 5 parts. Can anyone help with the correct number?

Thanks.

[wampcat1]

Great, thanks a million!

I have these mouser part numbers:
Cap= 0.1 UF Metal Film [5989-250V.1-F]
Diode = 1N4148 [512-1N4148]

But can't find the SK30A. I searched under "SK30 jfet"  and found 5 parts. Can anyone help with the correct number?

Thanks.

The fellow above you used a j201 and it worked just as well -- I'd try one of those if you can't find the other.

bw