My phase 90 clone isn't working

[snow123]

is it normal for the signal to start to die at the 470k resistor? and im not getting any signal out of p1 or 2 on ic3.

[andy-h-h]

I'm confused - didn't you say that it's now working in this thread, before these recent posts?   

https://www.diystompboxes.com/smfforum/index.php?topic=127366.0

i was building a bluesbreaker pedal, and i had a minor issue with it, and fixed it.

So you're back to talking about the phase 90?  I thought you got this working too?

[snow123]

I'm confused - didn't you say that it's now working in this thread, before these recent posts?   

https://www.diystompboxes.com/smfforum/index.php?topic=127366.0

i was building a bluesbreaker pedal, and i had a minor issue with it, and fixed it.

So you're back to talking about the phase 90?  I thought you got this working too?

no i didnt, i just restarted building it, like i got a new veroboard and stuff to rebuild the circuit stage by stage

[snow123]

I'm confused - didn't you say that it's now working in this thread, before these recent posts?   

https://www.diystompboxes.com/smfforum/index.php?topic=127366.0

i was building a bluesbreaker pedal, and i had a minor issue with it, and fixed it.

So you're back to talking about the phase 90?  I thought you got this working too?

no i didnt, i just restarted building it, like i got a new veroboard and stuff to rebuild the circuit stage by stage

i just took your advice and finished a much simpler pedal (that i already built but wasnt working) than the phase 90.

[andy-h-h]

is it normal for the signal to start to die at the 470k resistor? and im not getting any signal out of p1 or 2 on ic3.

If you mean along this path, then no it should not.   The red line is the clean signal path (noting that it exits pin 1).

[snow123]

ok, i just swapped out the tl072 with a new one and it now no longer sounds like the signal is dying, so do i do the rest of the clean signal path or start building the phase shifting stage?

[andy-h-h]

ok, i just swapped out the tl072 with a new one and it now no longer sounds like the signal is dying, so do i do the rest of the clean signal path or start building the phase shifting stage?

This is harder than a Bluesbreaker to build step by step - and generally just harder to make.

If you have clean signal coming out of the buffer, you could do the rest of the output stage if you wanted to.  You will need to have a very firm understanding of the schematic against the layout to have any chance of building this stage by stage.  JFETS can also be pesky things with odd pinouts and inconsistent performance.

There's;

an input buffer (opamp)
an output / mixer stage that blends clean and phased signals (the transistor)
1 x oscillator (the LFO)
4 x phasing stages using JFETS
+ the power section

Explaining how to go through this stage by stage is a bit more than I can commit to right now, and I still think you need to learn a bit more and improve your soldering.        Fingers crossed you have better luck this time.

[ElectricDruid]

Referring again to http://www.generalguitargadgets.com/pdf/ggg_p90_sc.pdf - although this is shown with all single op-amps, and your vero layout shows duals, so ignore the IC pin numbers.

Start with the power supply components: D1, R16, C6, D2, R22 trim. Step One!

Do the buffer IC1, R1, C1, R2.

If you've got good solid sound coming from pin 1 of your dual op-amp, the buffer is working. Hooray! Step Two.

Do the output mixer transistor: R27, Q5, R26, R28, C9, R29, R30. That completes the output stage, and you should have signal at the output end of R30. That's Step Three. R24 feeds in the signal from the phase stages, so we'll add that later.

After that, we can start work on the phase stages. But I've given you a lot to do there already, since you'll have to work out which component on the schematic refers to which component on the vero layout - but that's all good schematic reading practice. Take it steady and you'll get it.

[snow123]

when i probe the collector of the 3906 (instead of the 2n4125) and both ends of the 47nf cap it creates a weird glitchy sound. is that normal?

[antonis]

Is that glitchy sound also present at the Base of 2N3906, too..??

[snow123]

Is that glitchy sound also present at the Base of 2N3906, too..??

nope, i get a clean dry signal at the base.

[snow123]

i just resoldered the socket (there was some pretty suspicious areas), and replaced the 47n cap in that area, and now on the collector and on 1 side of the 47n cap, theres a much louder, less weak sounding glitchy-fuzz type sound getting out, and on the other side of the cap that signal gets much weaker. granted and i am just using the probe as an output rather than soldering the output to the circuit. but idk if that would affect the type of signal that gets out.

[snow123]

i just resoldered the socket (there was some pretty suspicious areas), and replaced the 47n cap in that area, and now on the collector and on 1 side of the 47n cap, theres a much louder, less weak sounding glitchy-fuzz type sound getting out, and on the other side of the cap that signal gets much weaker. granted and i am just using the probe as an output rather than soldering the output to the circuit. but idk if that would affect the type of signal that gets out.

and the signal on the base of q5 is still clean without any distortion

[ElectricDruid]

Ok, let's have a look at the voltages. It sounds like the transistor isn't happy with its biasing.

What have you got for the power supply and Vref voltages? What have you got at pins B, C, E on the transistor?

[snow123]

Ok, let's have a look at the voltages. It sounds like the transistor isn't happy with its biasing.

What have you got for the power supply and Vref voltages? What have you got at pins B, C, E on the transistor?

q5 voltages:

C = 0.0
B = 4.3
E = 4.8

[andy-h-h]

Ok, let's have a look at the voltages. It sounds like the transistor isn't happy with its biasing.

What have you got for the power supply and Vref voltages? What have you got at pins B, C, E on the transistor?

q5 voltages:

C = 0.0
B = 4.3
E = 4.8

0 on the collector is not right.   Check for shorts to ground.  Photos?

[snow123]

Ok, let's have a look at the voltages. It sounds like the transistor isn't happy with its biasing.

What have you got for the power supply and Vref voltages? What have you got at pins B, C, E on the transistor?

q5 voltages:

C = 0.0
B = 4.3
E = 4.8

0 on the collector is not right.   Check for shorts to ground.  Photos?

[andy-h-h]

You don't have the 56k resistor going to the collector on the board - add that and you should get it going.

What's going on with the two electrolytic caps next to D1?  Are they in series, and what values are you using?  They would have to be 47u and 22u to equal approx 15u as asked for on the layout.

If you plan on building a few pedals, get a cheap breadboard or make a test rig so you can work on it not attached to an enclosure and switching.  It will make your life a lot easier   

[snow123]

You don't have the 56k resistor going to the collector on the board - add that and you should get it going.

What's going on with the two electrolytic caps next to D1?  Are they in series, and what values are you using?  They would have to be 47u and 22u to equal approx 15u as asked for on the layout.

If you plan on building a few pedals, get a cheap breadboard or make a test rig so you can work on it not attached to an enclosure and switching.  It will make your life a lot easier   

those 2 electrolytics are in series (10uf+4.7uf) for the 15uf cap

[andy-h-h]

You don't have the 56k resistor going to the collector on the board - add that and you should get it going.

What's going on with the two electrolytic caps next to D1?  Are they in series, and what values are you using?  They would have to be 47u and 22u to equal approx 15u as asked for on the layout.

If you plan on building a few pedals, get a cheap breadboard or make a test rig so you can work on it not attached to an enclosure and switching.  It will make your life a lot easier   

those 2 electrolytics are in series (10uf+4.7uf) for the 15uf cap

10u and 4.7 in parallel will get you close to 15u.   The values you have used in series works out to just over 3u.   

Capacitors in series and parallel work differently to resistors.