Spencerleehorton
Well-known member
Hi Guys,
have tried to find what the problem is but cant seem to track it down!!
i have built a phase 90 pedal using 741 chips and have used SK30 or J201 as FETs, not at the same time, along with the 4125.
I am getting no dry signal and the pedal is just acting as a tremolo, no phasing?
I have printed out this pcb:
http://effectslayouts.blogspot.co.uk/2015/04/mxr-script-phase-90.html
all values are correct apart from the 47nf caps i have 33nf in there but i have tried 47nf and it sound the same, as there is no phasing to it at all?
voltages wise on the 741 im getting:
pin1 = 0v
pin2 = 4.97v
pin3 = 4.74
pin4 = 0v
pin5 = 0v
pin6 = 4.97v
pin7 = 8.41v
pin8 = 0v
all of the 741 are about the same.
the 4125 is E = 4.88, B = 4.24, C = 1.8 - 2.6v (varies up and down)
Q1,2,3,4 = D = 4.80, S = 4.60 - 4.80 (varies), G = 2.8 - 3.3 (varies)
I'm must be missing something obvious, i dont have a DPDT switch in, feel like im cursed again at the moment!!!
any help would be really appreciated.
regards
Spence.
have tried to find what the problem is but cant seem to track it down!!
i have built a phase 90 pedal using 741 chips and have used SK30 or J201 as FETs, not at the same time, along with the 4125.
I am getting no dry signal and the pedal is just acting as a tremolo, no phasing?
I have printed out this pcb:
http://effectslayouts.blogspot.co.uk/2015/04/mxr-script-phase-90.html
all values are correct apart from the 47nf caps i have 33nf in there but i have tried 47nf and it sound the same, as there is no phasing to it at all?
voltages wise on the 741 im getting:
pin1 = 0v
pin2 = 4.97v
pin3 = 4.74
pin4 = 0v
pin5 = 0v
pin6 = 4.97v
pin7 = 8.41v
pin8 = 0v
all of the 741 are about the same.
the 4125 is E = 4.88, B = 4.24, C = 1.8 - 2.6v (varies up and down)
Q1,2,3,4 = D = 4.80, S = 4.60 - 4.80 (varies), G = 2.8 - 3.3 (varies)
I'm must be missing something obvious, i dont have a DPDT switch in, feel like im cursed again at the moment!!!
any help would be really appreciated.
regards
Spence.