My phase 90 clone isn't working

[snow123]

ok, in summary; the phase effect (and most of the pedal) is working as it should be, but if i try to use the first 40% of the speed pot the signal disappears. but after that the signal is just fine..

[ElectricDruid]

Ok, here's what you've given us recently:

uhhhh i think there was a short on top of the board, and i fixed that, and now im getting a really bizarre, really quiet phase effect. and i hear it when probing the 150k resistor next to q5s base.

wait no, that weird phase effect only happens when the trimpot is maxed out, when i turn down the trimpot at all it turns into that weird sputtery fuzz type sound.

part of me wants to say the trimpot is the issue but i really doubt that, i also dont have any other 250k trimpots lol.

there was actually a short somewhere that was 'causing that super fuzz sound thing, now i fixed that and the small stone thing is back when it max out the trimpot!!

everything looks to be working as it was working before i went backwards.

yea i dont really know what the issue could be

the only thing i think could be the issue is the 3m9 resistor but i REALLY doubt that.

i just tried getting a better phase effect, and it seems like the pedal is working pretty well but when i turn the speed knob down (from ~11 o clock) the phase effect starts to disappear..

ok, in summary; the phase effect (and most of the pedal) is working as it should be, but if i try to use the first 40% of the speed pot the signal disappears. but after that the signal is just fine..

Now, *you* tell me what part of that train-of-thought thinking-out-loud we can actually work with?!? There's basically not much there that gives us any concrete information about your circuit, only stuff about what you *think* about your circuit. No voltages, no report of what you hear where, except for the final output. You're speculating. You have no idea. That's fine - that's why you're here asking us instead.

The only actual clues in any of that is that you're only getting phasing in a certain frequency range of the LFO, and that the LFO trimpot isn't behaving as it should. Both of those things suggest problems in the LFO circuit, so you're back to checking component value, shorts, and voltages in the LFO part of the circuit. This is actually a MASSIVE step forward because it means that we've most likely got all of the audio path working eventually and we're only a few tweaks away from a fully-working pedal! So don't give up! We're really close!

So let's have some voltages around the LFO op-amp this time. If you don't know where or what that is, for god's sake ASK! A wise teacher of mine used to say that "the only stupid question is the one you don't ask". This advice has stood me in good stead and I've learned a lot by asking stupid questions. Lots and lots of "stupid" questions. And now I know the answers to those and the people that didn't ask don't

[snow123]

Ok, here's what you've given us recently:

uhhhh i think there was a short on top of the board, and i fixed that, and now im getting a really bizarre, really quiet phase effect. and i hear it when probing the 150k resistor next to q5s base.

wait no, that weird phase effect only happens when the trimpot is maxed out, when i turn down the trimpot at all it turns into that weird sputtery fuzz type sound.

part of me wants to say the trimpot is the issue but i really doubt that, i also dont have any other 250k trimpots lol.

there was actually a short somewhere that was 'causing that super fuzz sound thing, now i fixed that and the small stone thing is back when it max out the trimpot!!

everything looks to be working as it was working before i went backwards.

yea i dont really know what the issue could be

the only thing i think could be the issue is the 3m9 resistor but i REALLY doubt that.

i just tried getting a better phase effect, and it seems like the pedal is working pretty well but when i turn the speed knob down (from ~11 o clock) the phase effect starts to disappear..

ok, in summary; the phase effect (and most of the pedal) is working as it should be, but if i try to use the first 40% of the speed pot the signal disappears. but after that the signal is just fine..

Now, *you* tell me what part of that train-of-thought thinking-out-loud we can actually work with?!? There's basically not much there that gives us any concrete information about your circuit, only stuff about what you *think* about your circuit. No voltages, no report of what you hear where, except for the final output. You're speculating. You have no idea. That's fine - that's why you're here asking us instead.

The only actual clues in any of that is that you're only getting phasing in a certain frequency range of the LFO, and that the LFO trimpot isn't behaving as it should. Both of those things suggest problems in the LFO circuit, so you're back to checking component value, shorts, and voltages in the LFO part of the circuit. This is actually a MASSIVE step forward because it means that we've most likely got all of the audio path working eventually and we're only a few tweaks away from a fully-working pedal! So don't give up! We're really close!

So let's have some voltages around the LFO op-amp this time. If you don't know where or what that is, for god's sake ASK! A wise teacher of mine used to say that "the only stupid question is the one you don't ask". This advice has stood me in good stead and I've learned a lot by asking stupid questions. Lots and lots of "stupid" questions. And now I know the answers to those and the people that didn't ask don't

so for some reason i thought that swapping the pot out would fix that , and it didnt. it actually removes the phase effect (that should be an easy fix), but turning the pedal on does make the signal go slightly out of phase, but anyways heres the voltages:

Q1-q4
D =  4.7
S = 4.8
G = 0 (?)

Q5
C = 3.1
B = 4.2/3
E = 4.8


ic3 (p5-8):

p5 = 4.9
p6 = 0 (??)
p7 = 7.7
p8 = 9.0

so im thinking theres something wrong with the 47nf thats next to q4s source and gate, and maybe the 10nf thats near q5.

[snow123]

and i replaced the 470k next to ic3 (ive been replacing parts instead of checking soldering 'cause i know that everything is soldered correctly and theres no shorts, and i replaaced the 470k and the 10nf 'cause the speed pot isnt doing anything and 'cause of the lack of voltage at p7.) and now theres no voltage at p6... so there is definitely an issue around the speed control and the LFO part of ic3. and maybe in-between the phase shifting stage and the lfo. but i doubt that theres anything wrong with the phase shifting stage since the signal is slightly going out of phase, but not oscillating at all.

[duck_arse]

why do you show a question mark against the gate voltage? if it is at 0V, the fets won't do anything, you need to adjust that trimpot to bias them into their happy place. do you still have a voltage on D2 [assuming tonepad circuit refs], the zener?

also, if an IC has eight legs, we want eight voltage readings, not 3 or 4. what you don't list might be the key.

[snow123]

IC1 (Top):

P1 = 4.7
P2 = 4.7
P3 =4.7
P4 = 0
P5 = 4.7
P6 = 4.7
P7 = 4.7
P8 = 8.9

IC2 (Middle):

P1 = 4.7
P2 = 4.7
P3 = 4.7
P4 = 0
P5 = 4.7
P6 = 4.7
P7 = 4.7
P8 = 8.9

IC3 (Bottom):

P1 = 4.7
P2 = 4.7
P3 = 3.2
P4 = 0
P5 = 3.2
P6 = 0
P7 = 0
P8 = 8.9

5v1 zener (diode test):
4.29.

5v1 zener (200 dcv):
-4.7 (not sure why its negative when i have the negative probe on the cathode)

and the trimpot does affect the jfets gate voltage but it doesnt oscillate.

[duck_arse]

5v1 zener (200 dcv):
-4.7 (not sure why its negative when i have the negative probe on the cathode)

I'm guessing this means you have the red probe on the ground. which is wired negative ground. so the meter is ground referencing the positive zener voltage, and reading how far below it, how much more negative, ground is.

IC3 (Bottom):

P1 = 4.7
P2 = 4.7
P3 = 3.2
P4 = 0
P5 = 3.2
P6 = 0
P7 = 0
P8 = 8.9

from this I'm guessing IC3 pins 5, 6 and 7 are the input buffer, IC1A on the [once seen, long ago] tonepad circuit diagram. pins 6 and 7 should read anything but 0, so there is either a fault there, or a mis-reading.

and the trimpot does affect the jfets gate voltage but it doesnt oscillate.

the zener is meant to provide a steady voltage reference. the trimpot is meant to read that voltage, and tap-off a divided, also stable, voltage of your choice. lower than reference, but higher than ground/0V. the voltage at the trimpot is not meant to oscillate or waver. it is a reference, and is held away from the oscillations by the 1,000,000 ohms of resistance attached to its wiper. the far end of that resistor is meant to provide a bias to the jfet gates, that bias being tuned by you to the point where the jfets do their thing, and change their resistance in accordance with the applied oscillator output, via the 3M9. phasing your signal.

so you need signal thru the input buffer, and a voltage bias on the gates, and an oscillating signal on the gates, if you want phasing at the output.

you only need to use the 20V DC setting for pedal work. always take voltage readings with the black probe on ground. use the diode test range when the diode is not soldered to the circuit.


alright, on second look, not the input buffer. if those 0V pins are the oscillator stage, you look to have a short of some description, somewhere around pins 6 and 7.

[snow123]

5v1 zener (200 dcv):
-4.7 (not sure why its negative when i have the negative probe on the cathode)

I'm guessing this means you have the red probe on the ground. which is wired negative ground. so the meter is ground referencing the positive zener voltage, and reading how far below it, how much more negative, ground is.

IC3 (Bottom):

P1 = 4.7
P2 = 4.7
P3 = 3.2
P4 = 0
P5 = 3.2
P6 = 0
P7 = 0
P8 = 8.9

from this I'm guessing IC3 pins 5, 6 and 7 are the input buffer, IC1A on the [once seen, long ago] tonepad circuit diagram. pins 6 and 7 should read anything but 0, so there is either a fault there, or a mis-reading.

and the trimpot does affect the jfets gate voltage but it doesnt oscillate.

the zener is meant to provide a steady voltage reference. the trimpot is meant to read that voltage, and tap-off a divided, also stable, voltage of your choice. lower than reference, but higher than ground/0V. the voltage at the trimpot is not meant to oscillate or waver. it is a reference, and is held away from the oscillations by the 1,000,000 ohms of resistance attached to its wiper. the far end of that resistor is meant to provide a bias to the jfet gates, that bias being tuned by you to the point where the jfets do their thing, and change their resistance in accordance with the applied oscillator output, via the 3M9. phasing your signal.

so you need signal thru the input buffer, and a voltage bias on the gates, and an oscillating signal on the gates, if you want phasing at the output.

you only need to use the 20V DC setting for pedal work. always take voltage readings with the black probe on ground. use the diode test range when the diode is not soldered to the circuit.


alright, on second look, not the input buffer. if those 0V pins are the oscillator stage, you look to have a short of some description, somewhere around pins 6 and 7.

i meant the jfets gate voltage doesnt oscilate.

[ElectricDruid]

alright, on second look, not the input buffer. if those 0V pins are the oscillator stage, you look to have a short of some description, somewhere around pins 6 and 7.

+1 what DA says. The half of IC3 that is supposed to be doing the LFO looks terrible. 3 and 5 aren't great, but might be ok after whatever else is wrong is fixed. 0V on 6 and 7 is not at all right. You've got some shorts or bad joints or something on there.

Send a us a detail picture of just that area if you like and we'll take a look. If the LFO isn't working, the JFET gates won't ever be right, no matter how you adjust the trimpot. So it's crucial to get the LFO going.

[snow123]

alright, on second look, not the input buffer. if those 0V pins are the oscillator stage, you look to have a short of some description, somewhere around pins 6 and 7.

+1 what DA says. The half of IC3 that is supposed to be doing the LFO looks terrible. 3 and 5 aren't great, but might be ok after whatever else is wrong is fixed. 0V on 6 and 7 is not at all right. You've got some shorts or bad joints or something on there.

Send a us a detail picture of just that area if you like and we'll take a look. If the LFO isn't working, the JFET gates won't ever be right, no matter how you adjust the trimpot. So it's crucial to get the LFO going.

Here's some pics of the lfo area

[duck_arse]

remove those two caps - take them outside and throw them as far as you can. you have the theory correct, but not the execution. replace that cap with ONE ONLY 10uF, or a 22uF, or a 47uF, or even a 4u7, whatever you have, doesn't matter, just to get it to work. then retake and repost voltages, please.

nice-ish work on the 3M9.

[snow123]

remove those two caps - take them outside and throw them as far as you can. you have the theory correct, but not the execution. replace that cap with ONE ONLY 10uF, or a 22uF, or a 47uF, or even a 4u7, whatever you have, doesn't matter, just to get it to work. then retake and repost voltages, please.

nice-ish work on the 3M9.

i swapped those caps for a 22uf and now the signal is a bit more out of phase but still not oscilating, theres only a sweep while im adjusting the trimpot.

[snow123]

the trimpot is acting like a wah pedal but without the treadle. so the lfo is just stuck i guess.

[snow123]

the trimpot is acting like a wah pedal but without the treadle. so the lfo is just stuck i guess.

as in its only making that phase effect when im actively turning the trimpot.

[duck_arse]

are you going to post the voltages on that opamp, the oscillator one? if you still get 0V on any pin other than pin 4, power off, pull the IC, set your meter to low ohms range, and probe the empty socket. test pin 8 to pin 7, then pin 7 to pin 6, then pin 6 to pin 5, then pin 1 to pin 2, etc ..... THEN test pin 8 to pin 1, pin 7 to pin 2, pin 6 to pin 3, and pin 5 to pin 4. except for pins 1 and 2, you will probably -- well, you should, on a woorking circuit -- get wobbly nonsense readings - we don't really care about those. we want to know where you find a steady, low resistance reading.

actually, YOU want to know moreso than we do.

[snow123]

are you going to post the voltages on that opamp, the oscillator one? if you still get 0V on any pin other than pin 4, power off, pull the IC, set your meter to low ohms range, and probe the empty socket. test pin 8 to pin 7, then pin 7 to pin 6, then pin 6 to pin 5, then pin 1 to pin 2, etc ..... THEN test pin 8 to pin 1, pin 7 to pin 2, pin 6 to pin 3, and pin 5 to pin 4. except for pins 1 and 2, you will probably -- well, you should, on a woorking circuit -- get wobbly nonsense readings - we don't really care about those. we want to know where you find a steady, low resistance reading.

actually, YOU want to know moreso than we do.

IC3 (Bottom):

P1 = 4.8
P2 = 4.8
P3 = 4.6
P4 = 0
P5 = 0
P6 = 0
P7 = 8.1
P8 = 9.4

[snow123]

are you going to post the voltages on that opamp, the oscillator one? if you still get 0V on any pin other than pin 4, power off, pull the IC, set your meter to low ohms range, and probe the empty socket. test pin 8 to pin 7, then pin 7 to pin 6, then pin 6 to pin 5, then pin 1 to pin 2, etc ..... THEN test pin 8 to pin 1, pin 7 to pin 2, pin 6 to pin 3, and pin 5 to pin 4. except for pins 1 and 2, you will probably -- well, you should, on a woorking circuit -- get wobbly nonsense readings - we don't really care about those. we want to know where you find a steady, low resistance reading.

actually, YOU want to know moreso than we do.

and im not getting any steady readings anywhere on the socket.

[Slowpoke101]

Re-install the link shown in the following image;


Click on image to download

One leg appears not to be soldered.

Edit;

Also, from your voltage readings of the LFO, pin 5 can only be at 0V if it is shorted to 0V somewhere. Pin 6 is most likely at 0V because of the link that is not correctly soldered. Please refer to the following image;

[snow123]

Re-install the link shown in the following image;


Click on image to download

One leg appears not to be soldered.

Edit;

Also, from your voltage readings of the LFO, pin 5 can only be at 0V if it is shorted to 0V somewhere. Pin 6 is most likely at 0V because of the link that is not correctly soldered. Please refer to the following image;

just did that, getting nothing else.

[Slowpoke101]

I hope that your multimeter is now working correctly. I haven't been following this saga very closely.

Make certain that your effects circuit is not powered (remove the battery or disconnect power - whatever), set your meter to low resistance measurement. Short the test leads together and note what reading you get, then see what reading you get when you test pins 4 and 5 of the LFO IC (place one test lead on pin 4 and the other lead on pin 5). Are the the readings the same?