Author Topic: Tractor Beam distorted?  (Read 1822 times)

madbean

  • Administrator
  • Electron Doctor
  • *****
  • Posts: 9344
  • Brian
    • View Profile
    • madbeanpedals
Re: Tractor Beam distorted?
« Reply #15 on: January 30, 2018, 06:12:18 PM »
You have a lot of excess solder on those joints, but I don't think that has much to do with your issue. Your work-around on the 10k resistor seems fine. Getting clean signal through when you pull the FETs is good - it means that the problem is either those FETs or the LFO. If you are getting oscillating voltages on the LM358 then by process of elimination it is most likely the FETs. If yo uhave any other FETs it might be helpful to pop them in there...even if they are not matched just to see what happens.
I own madbeanpedals (duh). I am part owner of Function F(X).

greenskull

  • Diode Destroyer
  • *
  • Posts: 20
    • View Profile
Re: Tractor Beam distorted?
« Reply #16 on: January 30, 2018, 06:32:21 PM »
Thanks, Brian. A lot of extra solder due to me trying to reflow in hopes of correcting a possible cold joint. I'm getting the right voltages on the LM358, so it is more than likely the jfets. I'll try to rustle up some others to try and will report back.... hate to give up!

madbean

  • Administrator
  • Electron Doctor
  • *****
  • Posts: 9344
  • Brian
    • View Profile
    • madbeanpedals
Re: Tractor Beam distorted?
« Reply #17 on: January 30, 2018, 06:34:24 PM »
A tip: don't need to add solder to reflow. Just work the existing joint. However, if you are reflowing a lot of joints at once it's a good idea to remove ICs temporarily to prevent the part from overheating.
I own madbeanpedals (duh). I am part owner of Function F(X).

greenskull

  • Diode Destroyer
  • *
  • Posts: 20
    • View Profile
Re: Tractor Beam distorted?
« Reply #18 on: February 01, 2018, 03:53:11 PM »
No luck  :(. Even tried using 2n5457's (flipped around) and changed out all the chips. I'm going to put it aside for another day and go on to a phase 90. If the jfets work cleanly in it, I'll try to mod it to do some of the Tractor Beam stuff. 8)