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PostPosted: Mon Jan 16, 2023 11:19 am 
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Hi all.

My Phase Royal (version 1.0) that I built approximately 10-11 years ago is suddenly sounding more like an overdrive than a phaser! It has worked as expected throughout the years. I switched it on last night and noticed a distorted sound coming out of the pedal. The last time I tested the pedal before last night was about six months ago.

Here are some pics (this was one of my first builds, so there is some not-so-pretty stuff).

Description of the behavior:
When clicking on the pedal, I can hear minor traces of a phasing sound, but it is not very prominent. Turning the knobs does change this phasing sound somewhat. I have a clipped signal like a warm overdrive. Turning the knobs does not seem to change this overdrive-like sound. The LED works, bypass works, the pedal worked as expected until the test last night.

What changed?
I have a pedalboard that had not had the configuration changed for many years. Recently I have been experimenting around and had this pedal off the board for several months. Last night it was placed back on the board, with a different power supply, different spot on the chain, different signal cables, etc. In order to verify it was not the signal cables or the power supply, I connected to pedal up by itself directly to amp/guitar and with another power supply that is known to work. The distorted behavior was the same, so I do not believe this is a result of changing my configuration around.

I see this "white stuff" on the solder joints for the IC socket that sits on the opposite side of the board. I don't know if it has anything to do with the problem or not, but I don't see it anywhere else. I see a couple of joints that look like they could use a reflow, but nothing else is really jumping out at me. I don't understand why this would happen suddenly.

Any ideas? Also, does someone have a high-res schematic for this version? I can find the old instructions, but can't read the schematic!

Thank you for your time,
John


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PostPosted: Mon Jan 16, 2023 12:30 pm 
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(I am assuming the schematic you have is about like the one in this thread: http://www.byocelectronics.com/board/viewtopic.php?f=29&t=39393)

Does the output change at all with the position of the MIX knob? Does it seem overall any louder than it used to? Sometimes "it is distortion now" means an amp (an op amp, say) no longer has the negative feedback it needs to tame it. Is the back-mounted IC (which I think is the one with the "white stuff" now present) the one that is configured as a voltage follower/buffer at the input, in that schematic? If there is a failure at that part of the circuit, which seems unrelated to the LFO, it might lead to the collection of symptoms you report. I think a single problematic solder joint could cause that.

I ask about the MIX knob in order to know whether an op amp loss of negative feedback might instead be among the all-pass filters in the upper half of the schematic. If it sounds distorted at all positions of all knobs (which I think is what you meant) then I'd look first at the voltage follower at the input.


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PostPosted: Tue Jan 17, 2023 3:03 pm 
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Hi. Thanks for responding!

Yes, my schematic is the one that is four images down on the thread. The mix knob did not seem to have any effect on the distorted sound.

I have re-flowed all of my joints near that IC, but I'm not 100% sure if that IC corresponds with that first buffer chip in the schematic or if it is one of the others. I have also touched up a few more spots which looked bad. I don't know what happened inside that pedal...maybe it's time I started cleaning my boards?

I was almost ready to test tonight, but... I screwed up my wiring and need to redo those. I probably won't be able to do that until later in the week. I'll respond back when I have tested again.

Thanks again for your time!


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PostPosted: Tue Jan 17, 2023 3:36 pm 
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I'm just going to put some links in here for future reference.

http://byocelectronics.com/phaseroyalinstructions-old.pdf

http://www.byocelectronics.com/board/viewtopic.php?f=29&t=39393 (scroll down a bit for the PCB map)


... edit 2023 Jan 18: Gee, if I would just look on the home page under the "How-to Info" section I might find a convenient listing of schematics, such as this clearer one:

http://byocelectronics.com/schematics/phaseroyalschematic.pdf


... edit 2023 Jan24, a message for future readers: If you have found your way to this thread because of interest in this older Phase Royal kit, even though it has been superseded, know that a lot of information about how it works and what mods have been tried (or just contemplated) can be found in these older threads (which are referred to here and there in posts farther down in this thread). CaptainPeyote had requested that in one of them that it be "stickied" but since I have been unable to find such, I'm linking them here:

http://byocelectronics.com/board/viewtopic.php?f=29&t=40310

http://www.byocelectronics.com/board/viewtopic.php?f=12&t=40729


Last edited by WMP1 on Tue Jan 24, 2023 9:15 am, edited 3 times in total.

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PostPosted: Wed Jan 18, 2023 11:41 am 
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I would suspect that one of the 5 op amps may have gone bad. I'd suggest swapping a known good one into each IC position sequentially and see if the problem disappears with one of the substitutions. If you have another working pedal with a socketed dual op amp, you can pull it from there to try this. Otherwise, buy one from BYOC, Mouser, DigiKey, etc. Don't buy the crap currently coming out of China.

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PostPosted: Wed Jan 18, 2023 12:55 pm 
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Posting op amp voltages would be helpful...maybe. I would suspect the problem would be with a semiconductor. So you can swap out all the op amps with know good op amps. If that doesn't fix it, definitely take voltages as a next step. Maybe the zener in the voltage divide popped. Improper bias voltage would cause the op amps to distort.

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PostPosted: Wed Jan 18, 2023 12:57 pm 
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Not being able to read the schematic well, I hesitated to make this suggestion about IC testing, but duhvoodooman has gone there:

If the problem is with one of the ICs and not the rest of the circuit, you indeed may be able to chase down a faulty IC by swapping in another, in sequence until satisfied, for the five various dual op amps in your pedal; if you don't have a spare one from somewhere else, you could start with the IC that corresponds to the two extra phase shift stages, if in fact both of those op amps are on the same chip. Since the schematic image is smudged, I'm not sure which one it is (or even if it is both op amps on one IC), but I would guess IC5. (See the links in my previous message.) That is, set the switch for 4 rather than 6 so that that pair of op amps is not being used anyway. Then you can try that IC in place of the others.

I have another hesitancy, which is that if it is a bad IC, and the badness was caused by something else wrong in the circuit, I suppose there is a risk of damaging whatever other IC you put in there.


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PostPosted: Thu Jan 19, 2023 11:55 am 
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Hi all.

Thanks for the responses! I have reflowed several suspect joints. One of the most egregious ones had a half-missing pad on R25, going to the mix pot. I've got my wires back on the board but need to get them on the power jack and output jack. Thanks for the tips about the opamps! I would have been bummed if I got it together and then had to pull it apart again. I do have a selection of TL072s (these should also work?) and 4558s sitting around at home, so I will swap them before buttoning it all up.

Hopefully I'll be able to test this weekend!

John


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PostPosted: Thu Jan 19, 2023 2:19 pm 
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shaman wrote:
...I do have a selection of TL072s (these should also work?)

Yep--TL072, TL082, 4558, 4559, NE5532, etc.--any of those general purpose dual op amps should work fine.

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PostPosted: Thu Jan 19, 2023 4:30 pm 
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I notice the OP said this was an old Phaser, from a decade ago. I built one at that time, too, and it had the same issue right from the get-go. It's been a long time but if memory serves, this was a known issue with the design and somebody here came up with a fix. Could this be that same issue, and does anybody remember the original fix? I think it was just a resistor value or something similar and easy to change. I can't remember the name of the member that identified the problem and fix, but they were an electrical engineer and came off a little rude so I think they may have eventually been banned?

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PostPosted: Thu Jan 19, 2023 9:34 pm 
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I don't think this is the same issue, because our OP specifically comments that this was a sudden change in the output sound after the pedal had "worked as expected throughout the years." Given this "step change" in performance, I think it's much more likely to be a failed component (IC would be my guess) or perhaps a solder joint that let go.

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PostPosted: Fri Jan 20, 2023 10:32 pm 
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So progress, kind of.

I replaced the IC on the solder side of the board (I believe IC2) before I closed it up and tested. It sounded like everything was fixed. I played around for a few minutes, clicked the pedal off and jammed on some other things, then clicked the phaser back on. It was distorted sounding again.

Quote:
I have another hesitancy, which is that if it is a bad IC, and the badness was caused by something else wrong in the circuit, I suppose there is a risk of damaging whatever other IC you put in there.


This sounds like what could be going on, but I'm not sure. It was definitely sounding like the problem was solved with a fresh IC2 and then got worse.

Quote:
Maybe the zener in the voltage divide popped.


I checked the zener in diode mode on a Fluke. Although I don't quite understand diode voltage values yet, I noticed the value was smaller with the with the black probe to the cathode and larger with the black probe to the anode. Unfortunately I didn't record the values as I didn't have much time to work on it at the time. It "seemed" like it was good to me, but I don't know exactly what to look for.

Another observation: The distorted sound isn't nearly as bad if I switch to a guitar with mellower pickups. My main guitar has a pretty hot bridge pickup (Wilde humbucker- the long bar type), but that was the same setup I had back when I built the pedal, and I don't remember the distortion. If I go to a neck pickup or single coil, it's almost fine. The phasing effect seems to be working. It just seems too sensitive to a hotter signal. I also played around with the trimpot.

Here are my voltage readings. IC2 seems fishy to me, but with the time I've had I'm not sure where it's supposed to be.
IC1
1. 4.15
2. 4.15
3. 2.75
4. 0
5. Fluctuates 3-4
6. Fluctuates 3-4
7. Fluctuates 2-7
8. 9V

IC2
1. Fluctuates 3.7 - 4.8
2. Fluctuates 3-4
3. Fluctuates 3-4
4. 0
5. 0.98
6. 0.98
7. 1.37
8. 9V

IC3
1. 4.15
2. 4.15
3. 4.08
4. 0
5. 4.13
6. 4.15
7. 4.15
8. 9V

IC4
1. 4.15
2. 4.15
3. 4.13
4. 0
5. 4.13
6. 4.15
7. 4.15
8. 9V

IC5
1. 4.15
2. 4.15
3. 4.13
4. 0
5. 4.12
6. 4.15
7. 4.15
8. 9V


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PostPosted: Sat Jan 21, 2023 12:17 pm 
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Your IC voltages look very reasonable, including IC2. The "B" side pins of that op amp (5, 6 & 7) aren't connected to anything and so the voltages just "float". The zener output is a tad low at ~4.2V, which is apparently often the case in this circuit.

As you probably already know, the v.1.0 BYOC Phase Royal was designed to be a faithful reproduction of the MXR Phaser circuit at its core, but with added control options (resonance, depth, mix and # of phasing stages). As such, the circuit also has some of the same faults/shortcomings/sensitivities as the original MXR circuit--a tendency to clip/distort among them. But there are things that can be done to improve the pedal's performance in this regard. I'd suggest that you look through this thread in some detail: viewtopic.php?f=12&t=40729

As CaptainPeyote referenced, this was the thread that discussed the perceived shortcomings of the Phase Royal/MXR circuit and suggested options for improving it. You may wish to skim the heavy-duty electrical engineer's discussion in the first half of that page of the thread and cut to the chase here: viewtopic.php?p=352845#p352845

These are the two modifications done by forum moderators Morgan and yours truly that definitely reduced the circuit's distortion tendency--rebiasing the Q7 transistor and lowering the current-limiting resistance at R37 to get higher and more consistent voltage from the zener. The Q7 bias mod works very well for some pedals and less noticeably for others, but is easy to do and definitely worth trying. The R37 resistance mod raised my zener output to ~4.8V.

A couple of other mods that you may wish to try are as follows:

  • Raising the values of the C1, C11 and C12 caps if you want to get more bass in your output. I went to 150n at all three positions instead of the 47n stock value.
  • Disconnecting the Resonance control by removing C4 and R16, as described HERE, and my description of the impact on my PR HERE. Bottom line was that I liked it and left it disconnected.

Lastly, here's a better copy of the v.1.0 PR schematic:

Attachment:
phase_royal_schematic.gif
phase_royal_schematic.gif [ 105.85 KiB | Viewed 3373 times ]

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PostPosted: Sat Jan 21, 2023 11:15 pm 
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Thanks for the response duhvoodooman. When I first read that thread, I thought what was happening may have been common for the pedal and I was wasting everybody's time, but I learned a little more tonight.

I performed mod #1 as described in the thread. I didn't have a 68k resistor so I used a 51k (closest value I had). This did not reduce the overall distortion when the knob was at noon, but it did considerably clean up the dry signal when the mix is turned all the way clockwise. As described in the thread, it's almost transparent now when I have mix all the way to the right.

I then performed mod #2 (2.7k resistor) and verified this brought my vref up to 4.7. After adjusting the trimpot again I tested. This did not noticeably affect the sound when compared to results at the previous step. I decided to not go further with the mods for now since the others seemed a bit more permanent.

As a final step, I put a good opamp and tested after each in IC1, IC3, IC4, and IC5 (remember I had already replaced IC2, and with the dry signal sounding good I figured that was okay). At each step I continued to have a relatively harsh, distorted sound, only getting worse as I turn the mix knob counter-clockwise.

EDIT: I see IC1 is actually responsible for the dry. I knew this before but had a late-night brain poop. So I suppose the issue could also be in the LFO/bias section. I have a signal probe and could dig deeper, but getting the time for that kind of involved work is a challenge for me right now!

Other than playing with the mix knob I've left my controls like this:
Depth: about at noon (occasionally turning it up when biasing)
Rate: 2 o'clock
Mix: variable
Res: all the way counter-clockwise
Stages: 4

At this point it seems like it's in the phase stages portion of the circuit (I have been testing with 4 stages), possibly a transistor that is clipping. Although I can understand the circuit at a higher level, it gets a little out of my wheelhouse when getting to the transistor bias, etc (I've just recently built my first fuzz). I have checked my solder joints several times and am at a loss. I wasn't planning on building another phaser for a while, so I'd still like to figure it out. At the very least, I've learned quite a bit about this pedal in the process!

EDIT2: This is my first time really trying to understand a circuit such as this. Where does the control/bias network in the bottom center of the schematic connect in to the phase stages? I can't determine the output of that network. I guess I need to brush up on my schematic reading skills as well. :D

Thanks for your help everybody!
John


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PostPosted: Mon Jan 23, 2023 3:06 pm 
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I played around with it quite a bit yesterday, and I still feel it is not working as intended, despite the tendencies of the base circuit. I was almost sure the mods would clean it up, but they did nothing to affect the wet part of the signal to my ears. It's almost unusable except for quiet, slow, single notes. Granted, it's been a while since I really used it, but I certainly don't remember this.

I am going to use a signal probe to try and find where it's going sour, but it may be a while before I can get a couple of hours to sit down with it. I'll post back when I find out more.


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PostPosted: Mon Jan 23, 2023 4:23 pm 
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Quote:
Where does the control/bias network in the bottom center of the schematic connect in to the phase stages? I can't determine the output of that network. I guess I need to brush up on my schematic reading skills as well. :D


All those little "LFO" flags connect together; that is, the "bottom center" produces that signal and it gets fed into the JFETs.

Similarly for "Vref" that you see here and there, and there, and over here ...

By the way was the "IC1 pin3" voltage of 2.75 V you reported earlier a typo? I'm still trying to figure that one out.


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PostPosted: Mon Jan 23, 2023 10:11 pm 
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Hi WMP1.

WMP1 wrote:
All those little "LFO" flags connect together; that is, the "bottom center" produces that signal and it gets fed into the JFETs.


Thanks for this. Simple enough, but I was having a hard time putting it together. I knew the LFO was a part of the phase stages but didn't know where they connected up. (schematic reading fail on my part)

WMP1 wrote:
By the way was the "IC1 pin3" voltage of 2.75 V you reported earlier a typo? I'm still trying to figure that one out.


I checked my original handwritten notes and definitely not a typo. It's even slightly higher now that I've done the Mod#2 mod as described above (around 3V). The vref is coming up through R3 and going to pin 3 of IC1. I'm a little lost on this one. Is it supposed to be this way? The vref would be like a relative ground, correct? When I am taking these readings I do not have signal going through the pedal. I just have a little dual TS connector I plug in to power it up, if that means anything.

I also noticed something else really odd. While I was checking my readings again to respond to this post, I saw 18V on pin8 of all my ICs! I'm honestly not sure how that happened, but I double-checked it to be sure. Just at this time as I was going through my wtf's, I was called away, left the pedal powered and on, and when I returned it was back to 9V. I haven't been able to recreate this since. I may wind up desoldering the socket for IC2 so I can see what is going on under there exactly.


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PostPosted: Tue Jan 24, 2023 11:36 am 
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Your voltages all look good. Since you aren't getting any clipping in the dry signal, you can probably rule out IC1 and Q7 as the culprits, since they are only involved in the dry signal path. IC2 is only involved in the LFO and probably isn't relevant to your problem. If you turn the depth all the way down, the mix all the way wet, and the distortion goes away, then maybe the LFO is the problem....but probably not.

So based on this, I would assume that the problem is most likely somewhere in the phase stage section.

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PostPosted: Tue Jan 24, 2023 7:49 pm 
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shaman wrote:

...

I checked the zener in diode mode on a Fluke. Although I don't quite understand diode voltage values yet, I noticed the value was smaller with the with the black probe to the cathode and larger with the black probe to the anode. Unfortunately I didn't record the values as I didn't have much time to work on it at the time. It "seemed" like it was good to me, but I don't know exactly what to look for. ...



I don't think this will get you closer to a resolution to whatever is the fundamental problem but I've posted a little more info on this topic here:
http://www.byocelectronics.com/board/viewtopic.php?f=7&t=60106#p504710
The exact results you get may depend on whether or not you checked the diode in isolation, as opposed to soldered into the rest of the circuit, but there is the general idea.


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PostPosted: Fri Jan 27, 2023 10:01 am 
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Just a quick update. My zener is definitely bad (open in reverse bias direction). I pulled it off the board and tested it.

My voltages looked okay, so I don't know if it was bad all the while or the result of my screwing around. I would imagine it would have failed immediately as opposed to a "halfway there." I'm not sure if it was the original problem or not. The quest continues...


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PostPosted: Fri Jan 27, 2023 1:23 pm 
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Are you going to put another Zener in to replace the one that seems faulty?

Let me put this idea out there and see what the experts have to say. If the Zener is now out of the circuit, you could replace it with another resistor of the same value, or within 20%, as what you currently have for R37 (I think you may have modded in a value lower than 10k ?), and thereby change to an ordinary voltage divider for the establishment of Vref (supported somewhat by C17; more capacitance there would be better but it is what it is). With the possible exception of what is now going on at Q7 (I think you did a mod there too?) I don't see any strong loading of Vref compared to the relatively low ~10k rungs in the divider.

Given all the ~4.15 V readings on IC pins earlier (except for the IC1 pin 3, which I still don't understand) it seems that you did have a decent Vref established earlier, but with the Zener out of course you don't.

It could be I've overlooked something important/obvious/both and if so I look forward to suitable chastisement.


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PostPosted: Sun Feb 05, 2023 11:21 pm 
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Hi all.

I decided to just leave everything "stock," except for mod #1, which I liked. I replaced the zener (left out mod #2 this time) and also replaced all my ICs. It definitely sounds better: still pretty gritty but not fuzzy. I'm still not sure what the problem was, but it seems to be solved.

Thanks again for all the help! I learned quite a bit about how phasers work when looking into this!
John


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PostPosted: Mon Feb 06, 2023 10:23 am 
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shaman wrote:
...and also replaced all my ICs.....I'm still not sure what the problem was, but it seems to be solved.

That would be my best guess. Glad to hear that it's sounding much improved!

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