New (broken) pedal day!

[laurie]

I could swap the JFETs again, but could that really help identifying the problem?

No. The JFETs aren't strictly part of the signal chain.

There really isn't anything active in the signal chain than the opamps. Really hard to imagine that the opamps are causing it though - almost always they either work, or they don't.

What is the voltage across the 1N5230 Zener?

[Pepe]

There really isn't anything active in the signal chain than the opamps. Really hard to imagine that the opamps are causing it though - almost always they either work, or they don't.

That's what I thought as well, but I'm no expert.

What is the voltage across the 1N5230 Zener?

The multimeter says 5.09 V.

Can I desolder the zener to see if the distortion remains? I'm sure that I installed the battery clip correctly, so that shouldn't cause a problem.

[laurie]

There really isn't anything active in the signal chain than the opamps. Really hard to imagine that the opamps are causing it though - almost always they either work, or they don't.

That's what I thought as well, but I'm no expert.

What is the voltage across the 1N5230 Zener?

The multimeter says 5.09 V.

Can I desolder the zener to see if the distortion remains? I'm sure that I installed the battery clip correctly, so that shouldn't cause a problem.

5.09V is fine. If it was 9V or 0V that would be a problem.

[laurie]

The only things it can be are the input or output cap, or one of the opamps?

[Pepe]

I just saw a Phase 45 schematic that has the TL072 as opamps. I have two of these and I can try them in my faulty unit instead of the original opamps. I would install precision sockets in that case.

Or is a TL022 the better equivalent? I don't have one at hand, though.

[laurie]

I just saw a Phase 45 schematic that has the TL072 as opamps. I have two of these and I can try them in my faulty unit instead of the original opamps. I would install precision sockets in that case.

Or is a TL022 the better equivalent? I don't have one at hand, though.

TL072 is fine. I just have my doubts that it will fix it

[laurie]

Interestingly it was really hard to find data on the sn72l022p. It is a standard configuration dual opamp, but it looks like it was rarely used back in the day.

[Pepe]

TL072 is fine. I just have my doubts that it will fix it

Oh yes, yes, yes, it did!

I installed the sockets, placed the old opamps on them (I don't know if they were in the same order as before) and the distortion was still there. Swapped them for the new TL072CP opamps: sweet undistorted phasing!

It is late here, so I haven't had a chance to hear it through my amp.

[laurie]

Oh yes!!!!

[Pepe]

Before and after pictures: