Help with a missworking BOSS SG-1 clone Slow Gear from GGG. (V redings included)

[solderman]

Hi
I just finished a BOSS SG-1 clone Slow Gear from GGG. It works but only when the attack pot is almost contraclockwise (~0,5K) and the sensitivity is almost clockwise (~18K) in this position it does what it should. The volume rice is OK but the decay is very choppy. In all other positions wont open or close depending on where the pots are. The trimpot is almost clockwise. No soldering bridges or tracecuts etc found and all components checked for value and polarity.

No components from the schematics are changed except the FET that is replaced by a 2N5457 that is proven to work in this thing and the C17 that is exchanged 100mF but I have intrepid this as a filter cap so it shouldn't matter.


Does anyone have any suggestions, I´m quite stuck here. The thing works but then again it does not???

Link to schematics

http://www.generalguitargadgets.com/pdf/ggg_sgo_sc.pdf



LM741
1=0
2=4,46
3=4,36
4=0
5=0
6=4,49
7=8,65
8=0

Q1
C=8,95
B=3,94
E=3,52

Q2
D=5,63
G=5,1
S=5,63

Q3
C=8,95
B=6,15
E=5,95

Q4
C=6,08
B=3,41
E=2,88


Q5
C=5,60
B=2,1 and descending slowly to near 0 while measuring
E= 2,2 and descending slowly to near 0 while measuring

Q6
C=5,60
B=2,2 and descending slowly to near 0 while measuring
E=3,0 and descending slowly to near 0 while measuring

//Solderman

[Mugshot]

the Attack knob controls the time before the effect kicks in, so zero Attack means the effect 'clutches" the signal and processes it right when the signal passes. turning the Attack knob to past 12, you get longer Attack time before the circuit begins processing the signal.

the SEnsitivity knob controls pick attack to match it to your playing style or pick up strength. you may have to max the Sens knob if playing with hotter pick ups or picking harder, and the signal decays faster with higher sensitivity, while low-output pickups and softer picking will benefit from lower sensitivity (around 12-2:00 o'clock).

the trim pot inside the pedal controls the blend of wet and dry signal. if you want the full effect of the Slow Gear, set the trim pot to max (full CW).

idk, but this is how i think the SG's controls are supposed to function. that's how it is with mine (the schematic of which i also got from GGG).

[MikeH]

Q2 seems suspect to me- based on those voltages it's not conducting.  Check it's pinout; maybe it's backwards?

[Scruffie]

I just came across this old thread by accident and I might have a suggestion...

On my build I wasn't getting any swell at all just gateing and then I stuck an extra electrolytic in parallel with C6 on the schematic (that goes to the attack pot) IIRC it was 22uF as that gave the best swell but anyway, that basically got the unit going for me and seemed to be very important to the swell so perhaps you could poke a parallel electrolytic in there if you haven't scrapped the effect for parts by now.

[solderman]

Hi
No as a matter of fact I went so far that I hunted down and ordered the original FET and did some extensive trouble shooting before I gave up. I can't remember if I did what you suggested. I'm almost certain that I have that thing lying around somewhere. I'll try to find it, test and report back.
Thanks' for the tip