Blue Majic de-bug........please help!!!!

[fatt-one]

Hi Guy's,
I am building a Blue magic pedal,I'm using a board from GGG,I have put the circut togeather outside the box to start,to see if any tweaks are needed.........I have no effect when switched on,signal will pass through when the effect is by-passed....and the led was on for about a second before it went out...............I used the layout at GGG for wiring the pedal and all looks right.I made 2 changes to the circut,1 I used a 1.2 meg r in place of a 1.5 meg r for r8 as it was all I had.I replaced c13a and c13b with a single .001 cap.otherwise it's as the layout shows.I have 9 volts throughout the circut, drain voltage on the BS170 is 9 and also on the J201.Turning the trimmer does nothing to the voltage...........I used a DC plug from Radio Shack,I have the center pin to the ground plain,one of the remaining 2 lugs catches the red battery lead,the other lug catches the jumper from the board and the 8.2k resistor to the round side of the led...........could it be a ground issue? or am I missing something else.
Thanks
Fattone

[3/4 North]

I just built one of these, seems real easy to get a solder bridge with this board. Especially if you're tweaking the tone caps.  I did, which also fried the 500k pot.

[petemoore]

drain voltage on the BS170 is 9 and also on the J201
  Hmmm...could be the trimpot's is bad, or theres a bridge to 9v from the Drains, or...
  With the drains @9V of 9v supply there's no room for signal swing.

[fatt-one]

Hi Guy's,
Thanks for the replies!!!! I found a bridge!!! but it wasn't solder,the jumper(1n914) side trace was touching r1(4m7) I scraped the copper away but no luck................I will check the trimmer next,all the DC voltage's I get are the supply voltage or slightly under...................thank-you guy's I will keep looking!!!!!!!!!
Fattone

[fatt-one]

Hi Guy's,
I just double checked the DC voltage to the drains, 9.34 vdc on both the BS170 and j201.I checked the pot,reads 50k on the outside and will drop if I turn the wiper.no voltage swing on the trannys though.
Ant thought s!!!!!!
fattone

[fatt-one]

Hi Guy's,
SOMEONE QUE THE MUSIC TO "IF i ONLY HAD A BRAIN"!!!!!!!

I used the wrong type jack for the input!!!!!! changed to the proper one and BAM we have sound...........some initial thoughts,I need to mess with the mid boost as I don't hear alot going on.........also any ideas on how to get a hair more grit or dirt on this bad boy? I will re-read all the post's here to find some ideas,Is the 1.2m in place of the 1.5m costing me some grit because I don't hear a tube screamer in there yet!!!!!!

Thank-you all for the help!!!!!!!!!
Fattone

[3/4 North]

That mid-boost drove me crazy. I finally switched the 530p to 2200p just to get some sort of response.
One thing I've noticed is the mid-boost switch won't make any difference if the drive or volume is past 3/4 turn.

Mine has no grit, it's no replacement for a Tube Screamer.  But it does has a very good tone.

[blanik]

was someone sucessful at getting more drive from this thing??

[fatt-one]

Hi Guy's,
I will have to try raising the .001 up to get some kind of a boost going!!!


"Mine has no grit, it's no replacement for a Tube Screamer.  But it does has a very good tone"

So far I agree 100%!!!!! maybe a small booster circut in front of the BM,I agree the tone is very nice but more of a clean boost to me...It does break up alittle the harder you pick...but not enough for me..I could always try and socket the j201 and see if different ones sound better...
thanks
Fattone

[Doug_H]

The "mid boost" works for lower gain settings. With the gain maxed you won't notice a difference.

For more gain try another circuit The BM is intended to be a low-med gain blues pedal.

[fatt-one]

Hi Guy's,
I see what you mean about the mid boost,as long as the drive pot is set around 1/2 way or less I hear some mids being boosted.......................

The "mid boost" works for lower gain settings. With the gain maxed you won't notice a difference.

For more gain try another circuit The BM is intended to be a low-med gain blues pedal.


I would be happy with some medium gain!!!!! my build is on lower side of the low gain spectrum
as mentioned in an above post,I will try a different j201 to see if maybe I have one that's got some higher gain going on.

Thanks
fattone