Build Your Own Clone Message Board

Gentlemen, I have completed building a Soaring Skillet and I am having a few issues with it.
I tested the IC voltages with the chips in and IC 1-4 the voltages are within tenths of a volt between chips.
With the exception of IC5, the one closest to the input jack.
Voltages for the 4 nearly identical IC's are as follows

Pins 1 = 4.3
Pins 2 = 4.3
Pins 3 = 4.3
Pins 4 = 0.0
Pins 5 = 4.3
Pins 6 = 4.3
Pins 7 = 4.3
Pins 8 = 8.7 (9.3v at the power supply)

Pin 1 on IC5 is fluctuating between 8.6v and 0.6v about every second. Is this normal?
The second issue is that the 4 trim pots, when rotated through their sweep, make no noticeable difference in the tone.
And finally, the tremolo is stereo but no panning or phaser effect.

Thoughts??? Questions???

Thanks, Steve0

P.S.
I've tried getting a better picture of the resistors etc. but I am not having any luck with the 1/8 watt little guys.

P.P.S. If a photo of the soldered side is needed, it'll take a minute, but I can make that happen.

_________________
“To know, and not to do, is not to know”

This is what the value at Pin 1 of IC5 looks like if I sweep the value of the Pan Rate pot (updated to show DC voltage):



So I would definitely expect to see that moving around, it would be part of the oscillator for the pan circuit, I think.

I'm happy to take measurements from my working Soaring Skillet if that would be helpful.

IC5a and IC1b are the tremolo and phaser LFOs respectively. So you are supposed to see fluctuating voltages there. The fact that you are not seeing fluctuating voltage on 1a is not a good sign.

You've got a lot going on here. It's probably best to just focus on one thing at a time. Let's start with the tremolo and the lack of panning. Am I correct in understanding that you have tremolo, but both the left and the right are modulating together rather than 180 degrees apart?

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

"Am I correct in understanding that you have tremolo, but both the left and the right are modulating together rather than 180 degrees apart?"

That is correct Keith.

_________________
“To know, and not to do, is not to know”

If you look at page 3 of the schematic, it shows the tremolo/panning circuit. IC5a is the LFO. The output from the LFO goes first to IC5b. This is a non-inverting buffer. The output from this buffer goes to "X" or the left channel. This output also goes to IC4b, which is an inverting buffer. This inverting buffer changes the phase 180 degrees. This is the output to "Y" or the left channel.

So if you aren't getting panning, but tremolo in unison, then my guess would be that you have a short somewhere in this region of the PCB that is causing one or the other phases of the tremolo LFO to be sent to both channels. Look for anything that may be causing this.

You could try removing IC4 from its socket and see how that affects the tremolo. That may give us some clues as to where the short is occurring. Try it at its slowest speed and see if you can here a phase jump when you take in and out of the socket.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

When I remove IC4 the pedal is dead. No signal getting through engaged or bypassed.

_________________
“To know, and not to do, is not to know”

Bump~

_________________
“To know, and not to do, is not to know”

Oh. Yeah. IC4a is the input stage to the phaser and signal always passes through the phaser.

Have you reflowed your solder joints yet? It sounds like you've got a cold solder joint somewhere in the phaser LFO and a short somewhere in the panning LFO.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I looked at the solder joints from the top side with a magnifying glass and touch up a few suspects. But I have not removed the PCB from the enclosure to properly inspect it.
I will remove the PCB, reflow all joints and report back with any changes.

Thanks!

_________________
“To know, and not to do, is not to know”

One time I had a build that drove me almost to the point of madness. I knew I had a short somewhere, but couldn't find it for the life of me. I eventually did find it. It eneded up being a tiny strand of hook up wire that was stuck under an IC socket. Poke around with your meter set to continuity test. See if you notice something that doesn't make sense.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Okay Keith, thanks. I'll keep probing around for a solution.

_________________
“To know, and not to do, is not to know”

I "finished" this build back in August of this year and it wasn't functioning properly. After looking at the PCB until my eyes bled, I decided to shelve it for awhile.
I took it off the shelf today after watching the BYOC video on YouTube featuring the Soaring Skillet (https://www.youtube.com/watch?v=g55t6YGutSQ).
The first thing I tested through the amps was the phaser circuit. That circuit is functioning perfectly. Then I pulled the cable on the right channel and tested the
tremolo on the left side. Other than a slight volume drop when the switch was engaged, the tremolo on the left channel worked fine. Unplugging the left side and connecting
the right, when I engage the switch there is a huge drop in volume. I have to put my ear by the speaker to hear it, but there is a very very slight tremolo effect happening.
As discussed earlier in this thread, the voltage on pin 5, of IC5, is only fluctuating a couple of tenths of a volt but should match the voltage on IC1 pin 5 which is fluctuating
like crazy. Any thoughts or direction will be greatly appreciated...

_________________
“To know, and not to do, is not to know”

It kind of sounds like the pedal is more working than not working. Have you tried using your signal tester to see where along the path(s) in the upper section of Page 3 of the schematic the signal coming in gets treated differently for the two outputs--or, if no change, then maybe where (and under what circumstances) the signal gets lost in the switching paths on Page 1? I don't have this pedal so I can't offer comparisons, but I could probably kibitz about which test points to prod.

Using a tone generator everything is good until the signal splits into right and left.

_________________
“To know, and not to do, is not to know”

So the question is, what is different about the two branches, that is not supposed to be?

I presume that in the lower branch, which appears not to be working properly, you have attempted to adjust VR7 (“pan right” trimpot) to make it sound correct, with no luck.

One way to continue is to try to see whether, apart from the X and Y signals coming in, there is some difference between the two branches. Maybe the JFET Q7 is bad, but may as well try to find other things first.

In your PCB photo the only possible difference I saw is based on resistor band colors, which in these photos of those little guys is hard to be sure of. It *looks* as if your R44 and R53, which are both supposed to be 470k, are different from each other. But the R53, in the “not-working branch”, looks like it’s got plausible colors for 470k (yellow purple black orange). The R44 is the one whose colors look off, but that is in the working branch. Still, maybe you could take a peek at those.

And in any case, see if voltages at the various available locations near the JFETs in the two branches more or less agree with each other.

As for what is fed into the JFET gates, the X and the Y, if I understand correctly those two signals are supposed to be the same except 180 deg out of phase, courtesy of the inverter (as explained by Keith in his posts above). I have the sense from previous posts here that if the panning (or tremolo) LFO is set to its lowest rate, it is slow enough that your voltmeter is able to show the varying voltage. If you’re not seeing a wide variation at Y, and the voltage is stuck at an unfortunate level, that could in principle explain both the weak or absent modulation and the low overall volume. So I think it would be worth setting the pan to as slow as possible, and exploring the X and Y locations (the gates of the JFETs) as well as the various pins of IC5b and IC4b to see what is going on with X and Y and what is supposed to create them. I think this repeats somewhat the things you have done before but it would help to track down where the problem is coming in.

You can measure those voltages w/r to GND as usual and you could also measure the voltage diff between X and Y which I suppose ought to have twice the amplitude of what either of the two them do, if they are both working.

If the Y signal isn’t running up and down similar to, but out of phase with, the X signal, then maybe there is something wrong with IC4b. I think Keith was trying to work out how to explore that before it was remembered that the other op amp in IC4 is needed earlier in the circuit … But perhaps you have a spare dual op amp you could put in there.

You can mark this one as solved!
I had checked and double checked the components on both sides of that circuit and knew them all to be of the correct values.
You mentioned that I was not getting any response when turning the VR7. And that turned out to be some what true.
When I previously tested the response from it I only went a little to the right and left of center because that's
USUALLY where the sweet spot is. However when I rotated it full clock wise, the right channel came alive! IC1 pin5
and IC5 pin5 now respond exactly the same on my DMM and the pedal functions as it was designed to!
My Chinese trimmer may be off a little more than 10%.

Thank you sir for your time and insight into this matter!
It is greatly appreciated!

-=Steve0

_________________
“To know, and not to do, is not to know”

Glad we could help, Steve…

_________________
Scott

My band, Austin Hollow

Woohoo! Enjoy, it a killer phaser.


Sent from my iPhone using Tapatalk

_________________
Pedal building is like the opposite of sex. All the fun stuff happens before you get in the box.

Might hafta get me one then.

Glad you got it working SteveO.

You should. FWIW, of all the BYOC phasers I've built, the Skillet is my hands-down favorite.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2