Boss DD-3 T (Third Edition) Effects Loop Help

[gravygeyser@gmail.com]

I've been attempting the fx loop mod on my dd-3 for a few days now but most of the posts on here refer to the older dd-3 model and the circuit board for the third edition has been changed up quite a bit. my problems so far have been that the fx loop doesn't modulate the first repeat and then it self-oscillates very quickly. i have the schematics for my pedal and the older model and there are some caps on my board where there are none in the older board, so i'm not exactly sure where to attach the send and return of the trs jack for the fx loop. Not sure if I should put a cap on my trs where the return comes in to stop it from oscillating.  If anyone has been successful with this mod on the newest dd-3 pedal, I would really appreciate some help.

Here is a link to the schematics for my the board in my pedal: http://music-electronics-forum.com/attachments/6882d1257549826-dd-3t_service_notes-1-.pdf

older board schematics: http://music-electronics-forum.com/attachments/4343d1233482513-boss-dd-3.pdf

[Johan]

what is the "fx loop mod" ?  do you have a link?
it would be easier to help if we knew what you talk about..
J

[gravygeyser@gmail.com]

It's mentioned in this post: http://www.diystompboxes.com/smfforum/index.php?topic=42738.msg309116#msg309116
It's also the mod that Keeley does here: http://www.robertkeeley.com/product.php?id=41

[slacker]

my problems so far have been that the fx loop doesn't modulate the first repeat

The first repeat just goes thorough the delay to the E.Level pot and to the output, it also goes through the F.Back pot back into the delay and comes out of the delay as the second repeat. The feedback loop mod you linked to places the loop after the F.Back pot so it won't effect the first repeat.

The part of the schematic where the mod goes is basically the same on both versions. I would do it by removing C51, connect a wire from the C51 pad nearest the F.Back pot, that's your send. Then connect a wire to the other C51 pad, that's your return, then put a cap between the jack and the return wire. You could use C51 for this if the leads are long enough.

[gravygeyser@gmail.com]

my problems so far have been that the fx loop doesn't modulate the first repeat

The first repeat just goes thorough the delay to the E.Level pot and to the output, it also goes through the F.Back pot back into the delay and comes out of the delay as the second repeat. The feedback loop mod you linked to places the loop after the F.Back pot so it won't effect the first repeat.

The part of the schematic where the mod goes is basically the same on both versions. I would do it by removing C51, connect a wire from the C51 pad nearest the F.Back pot, that's your send. Then connect a wire to the other C51 pad, that's your return, then put a cap between the jack and the return wire. You could use C51 for this if the leads are long enough.

So is there any way to modulate the first repeat as well? by putting the mod on the e. level pot maybe? or would that not work. 

Also, I'm pretty sure I had mine wired exactly the way you recommended and the fx loop would go into self-oscillation even when the feedback was turned down low.  Would putting a slightly stronger cap than the one already on the board help stop these self-oscillations. (the original cap is a 1uf cap) There's also probably a lot of noise in my chain that could make it do that, i'm not sure.

[gravygeyser@gmail.com]

sorry i know more about electronics than actual guitar effects. would this help reduce my pedal noise maybe getting rid of that annoying repeating noise: http://www.voodoolab.com/pedalpower_2.htm

[slacker]

So is there any way to modulate the first repeat as well? by putting the mod on the e. level pot maybe? or would that not work. 

Putting it on the E.Level pot would effect every repeat, but each repeat would only go through the pedal in the loop once, so the repeats wouldn't get more and more effect.   

[slowdive]

Sorry for posting on an old thread, but according to this thread http://www.diystompboxes.com/smfforum/index.php?topic=57203.0, putting the FX loop on Node 12 for the older version would affect the first repeat as well as increasing the effect on subsequent repeats. To me, it looks like that corresponds to C49 on the new schematic rather than C51. I have not tried it yet to confirm, but I will be attempting it soon. Just thought I would share that in case someone else comes across this post.