Tube Amps / Music Electronics
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|6/12/2004 3:14 PM|
||Son of Screamer - low output help please|
Fired up my Son of Screamer (Tubescreamer without the input & output buffer stages, as per Jack O's schem) today. Quiet, no hum or hiss.
BUT - though I get a signal, it is weak.
Gets stronger as you crank up Drive or level, but weak as a kitten.
Gets less trebly as you crank down treble, so the pots appear to be connected correctly.
All grounds check OK - input sleeve to output sleeve, to pot bodies, all grounded. Grounds on board check OK. Checked the IC in another stompbox, it works
1 - 4.5v
2 - 4.5v
3 - 4.5 v
4 - 0 V (ground checks OK to output sleeve)
5 - 4.5 v
6 - 4.5 v
7 - 4.5 v
8 - 9 v
R1 and R2 both at 4.5 v
Tone 1, 2, 3 lugs all 4.5 v
Level 1 & 2 - 0 v
Level 3 (goes to ground & checks OK)
Drive 1 & 2 - 4.5 v
What makes sense is no DC on the Level pot as the 1 uF C6 cap couples that.
What worries me is the 4.5v in the feedback loop (pins 1 & 2, first stage of the opamp). Shouldn't the cap C2 off the feeback loop to Vr (I use a .1mF though Jack specs a .05) block the DC into the feedback loop?
I got the schem from an article on GEO but you can quicklink it here:
thanks in advance
|6/13/2004 1:16 AM|
Fixed...no action needed.
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