My phase 90 clone isn't working

[Kevin Mitchell]

i fixed the volume loss, i was just missing a few parts in the area. but now that i did the LFO and all of the extra wiring, when i plug the pedal in, it just goes through the input buffer without going into the actual phase shifting circuit. basically, the pedal doesnt do the phasey thing when i turn it on.

Try to adjust the trimpot, see if the effect comes to life.

Turn the speed low and use your multimeter on the voltage setting to monitor the output of the LFO - so the gate pins (pins 1) of the jfets that connects to the 3.9M resistor. If you're not seeing the voltage swing then your lfo isn't working and there's an error. If it is working and you've verified that the guitar signal is making it through all phase stages, then your jfets would be suspect. Sadly they are one of the more commonly counterfeited parts. Not to scare you! Just a warning.

[snow123]

i fixed the volume loss, i was just missing a few parts in the area. but now that i did the LFO and all of the extra wiring, when i plug the pedal in, it just goes through the input buffer without going into the actual phase shifting circuit. basically, the pedal doesnt do the phasey thing when i turn it on.

Try to adjust the trimpot, see if the effect comes to life.

Turn the speed low and use your multimeter on the voltage setting to monitor the output of the LFO - so the gate pins (pins 1) of the jfets that connects to the 3.9M resistor. If you're not seeing the voltage swing then your lfo isn't working and there's an error. If it is working and you've verified that the guitar signal is making it through all phase stages, then your jfets would be suspect. Sadly they are one of the more commonly counterfeited parts. Not to scare you! Just a warning.

the gate pins are stuck at 4.7v..

[snow123]

and i adjusted the trimpot a bit and swapped out all of the transistors and nothings changed.

[Kevin Mitchell]

Are you an anecdotal horse?

Edit:
"You can lead a horse to water but you can't make him drink"

[ElectricDruid]

the gate pins are stuck at 4.7v..

So the LFO isn't working. What are the voltages on the relevant pins? (finding the relevant pins is left as an exercise for the reader )

[snow123]

the gate pins are stuck at 4.7v..

So the LFO isn't working. What are the voltages on the relevant pins? (finding the relevant pins is left as an exercise for the reader )

the relevant pins being p5, p6, and p7 on ic 3?

[ElectricDruid]

the relevant pins being p5, p6, and p7 on ic 3?

Exactly! Nice work!

Voltages there will give us some idea about the health of the LFO.

[antonis]

Voltages there will give us some idea about the health of the LFO.

An alive (in the mean of not dead) LFO doesn't necessarily indicate a healthy one..

[snow123]

the relevant pins being p5, p6, and p7 on ic 3?

Exactly! Nice work!

Voltages there will give us some idea about the health of the LFO.

ok, here:

P5 = 0.0
P6 = 2.2
P7 = 0.0

[ElectricDruid]

ok, here:

P5 = 0.0
P6 = 2.2
P7 = 0.0

So...no sign of the voltages varying at all then?

Those look terrible if they're fixed numbers. You should be able to see pin 7 switch from a high state (close to 9V, but not 9V) to a low state (close to 0V but not 0V - how close in both cases depends on which op-amp you use). The pin 6 voltage should follow the voltage on the 15uF cap, a triangle wave going linearly up and down - and the triangle frequency should be affected by that 500K rate pot.

Check the component connections for the LFO carefully, and not just the joints, but *where* they're joined. Looks like something is wrong there somewhere.

[snow123]

wait im an idiot. the 150k on p5 is in 1 hole too high.

[snow123]

ok now the voltage on p5 is 3.8

[snow123]

and the voltage on p7 is oscillating in between 3 and 6 volts!!!

[snow123]

still no phaser effect when completely plugged in.

[andy-h-h]

still no phaser effect when completely plugged in.

If it's passing audio as it should, but not phasing, time to check your JFETS.

[ElectricDruid]

still no phaser effect when completely plugged in.

If it's passing audio as it should..

Don't let's assume that. Snow123, can you check that? Have you got audio at the outputs of all the phase stages?

IC2 pin 1, IC1 pin 1, IC1 pin 7, IC2 pin 7

Sounds like good news with the LFO. I think we're making progress.

[snow123]

still no phaser effect when completely plugged in.

If it's passing audio as it should, but not phasing, time to check your JFETS.

the voltage on all of the jfets on all of the pins is 4.8

[snow123]

still no phaser effect when completely plugged in.

If it's passing audio as it should..

Don't let's assume that. Snow123, can you check that? Have you got audio at the outputs of all the phase stages?

IC2 pin 1, IC1 pin 1, IC1 pin 7, IC2 pin 7

Sounds like good news with the LFO. I think we're making progress.

there is audio in those places

[Kevin Mitchell]

I didn't see any mention of your JFets, are they matched?

i think so yea

So what's the story on these jfets?

Where did you get them?
Were they actually tested and/or matched?
-Did you purchased them as a matched set for this project?
-If you had tested and/or matched them, what method did you use and how many did you purchase to do this?

Again, jfets are commonly counterfeited. These parts are no longer manufactured in TO-92 packages so everything is either old stock or absolutely fake.

[snow123]

I didn't see any mention of your JFets, are they matched?

i think so yea

So what's the story on these jfets?

Where did you get them?
Were they actually tested and/or matched?
-Did you purchased them as a matched set for this project?
-If you had tested and/or matched them, what method did you use and how many did you purchase to do this?

Again, jfets are commonly counterfeited. These parts are no longer manufactured in TO-92 packages so everything is either old stock or absolutely fake.

I got a 20 pack off of Amazon.