Boss SD-1 Keeley 5 star mod problem

Started by romance, September 10, 2009, 08:23:24 AM

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romance

First off, I hope this is the right place to post this, I have gone through to check i have any soldering problems etc but i can't think of anything besides the components i used as to be the reason for the problem. I have recently started educating myself in electronics and modding pedals but I have recently had a problem with my diy Keeley 5 star Boss SD-1 mod which i can not debug.

When I engage the pedal it cuts almost all the high end and alot of the mids, and boosts the bass. It almost sounds like a light fuzz pedal with the guitar eq pot rolling off all the highs.

I used this (http://www.geocities.com/overdrivespider/SD1/stepfour.htm) diy walkthrough but had problems finding some of the components locally so i used aternatives.

The changes i made to the instructions:
-1Uf Capacitor (preferably metal film) x 2 : I used plastic coated ones instead, which seem to be larger than ones i've seen in stompboxes despite being the correct value.
-0.1uF Capacitor (preferably metal film) x 2 : I again used plastic coated ones instead, which seem to be larger than ones i've seen in stompboxes despite being the correct value.
-I have not (yet) swapped out/installed the 47pF capacitor or Germainium Transistor, which are optional anyway
-I swapped the stock small Boss red LED for a larger ~3mm white LED which lights up fine

What I did:
-Replaced C10 and C7 with 1uF capacitors
-Replaced C2 and C3 with 0.1uF capacitors
-Replaced R6 with 2.4k resistor
-Replaced R2  with 620k resistor
-Replaced D6 with Sillicum Diode
-Replaced small LED with ~3mm white LED



The only thing i can think of is the capacitors are not right because of their size (the green and red ones pointed out above), despite them being the correct value. OR I may have (hard to tell) seen a dammaged contact on one of the components after i used the solder wick to remove old solder on a contact, but it is now connected to the board just fine, and if it was this problem wouldn't the pedal just not work at all.

Any help is much appreciated as I am in the studio this Sunday and I do not want to buy yet anothert overdrive pedal when I like the sound i've heard of other peopls modded SD-1s.

Thanks alot

BAARON

The physical size of the capacitors will not be the problem.  Those poly caps are simply larger than the kinds of caps typically used by large manufacturers.

Looking at the mods you did, none of the 6 changes should cause a problem like you're describing.  All they should have done (so far) is allow a little more bass into the pedal and make the dirty end of the gain knob even dirtier, but nothing you did should have cut out the treble or mid frequencies.  I suspect something else on the board got damaged, so check for loose solder joints and bridged solder joints; I'd also check the wires leading to the tone pot to make sure nothing happened to them.

For the record, D6 was already silicon.  Replacing it with a different silicon diode will have practically no audible effect.
B. Aaron Ennis
If somebody makes a mistake, help them understand what went wrong.  Show them how to do it right.  Be helpful.  Don't just say "you're wrong, moron."

bside2234

Make sure the lugs of the pots aren't touching the lugs/sides of another pot or the sides of the enclosure.