Hello folks. After losing my Galacticon (phase 45) pcb and then finding it this morning :D I built it up and am getting no phase...not even a hint? It passes nice clean signal with even a slight boost but just no phase at all.
I tried a few different matched sets of 2n5457 (.77 Vgs) and also some matched 2n5952s (both 1.27 Vgs) with no luck. Verified orientation/pinouts as well.
Turning the trimpot has no effect on sound, nor does the speed or mix pots.
The only mod is I wired a 4PDT toggle into C2 and C3 to switch in univibe caps. I don't hear any effect switching the toggle either.
Thoughts?
Probe the LFO IC and make sure the voltage is varying.
I'd try different Zeners
I am getting varying voltage that changes with the speed control on LFO IC pin 7.
Have not considered the 4.7v zener? I assume if it was faulty I would not get any signal at all.
Quote from: pryde on December 09, 2013, 08:34:48 PM
I am getting varying voltage that changes with the speed control on LFO IC pin 7.
Have not considered the 4.7v zener? I assume if it was faulty I would not get any signal at all.
Now check resistance and voltages on the FET. In other words, make sure that the control voltage is getting to the FET. Work backwards if it isn't. If it is working, then something's wrong in the audio path.
The trimmer has a really narrow range, by the way.
Well after sorting through more 2457's I found another match at 1.06 Vgs and tried them: Whaddayouknow we got phasing :)
As you said Jon the trim pot range is VERY narrow to dial in but it is sounding good. I am a little surprised that the other matched ones won't work (.77 vgs) but they just don't bias up with the trimmer?
Anyway I love phase 45's and plan to box this one maybe in some sort of combo build ;D