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I am a musician and use a modular synth in two cases (powered by three uZeus power supplies), which runs into a Focusrite Scarlett sound card, then into an iMac, running the test OS. See attached photo.

I had to take my gear down while I did some work on my desk space. Having put it all back together I powered on my cases, and now my mac's cursor is acting like I am doing lots of right clicks. If I hover over a menu it starts spamming these phantom right clicks.

The uZeus power supplies are plugged into a different 6-way to the mac. This only happens when the eZeuses are on. The more of them I power on, the worse the issue becomes. Everything was fine for months before. I can't see anything I've changed.

Unplugging the Scarlett's USB power stops the issue. So does unplugging the 1/4" jacks from the front. But obviously these are not fixes.

The mouse is a magic trackpad so has no (changeable) batteries. The issue also occurs using a wired mouse - and with no mouse plugged in, and bluetooth turned off.

I have plugged the zeus power supplies into a different wall outlet + extension. No difference.

It even happens when the main (Scarlett-connected) rack is off, but a second rack is powered on, which is not connected to the Scarlett. But if I then unplug the Scarlett from the main rack (which is off), it stops.

There are no other new devices in the house. I live on the end of a block. My only neighbors are decidedly not into tech.

I know of no external works in the neighborhood in the 2-3 days since unplugging everything.

Again, there has been no change that I know of in my home or my immediate area, and everything was working perfectly prior.

Moving the Zeus power supplies into a different socket has made a difference in reducing the spamming of the menus, but not eradicated it.

Any observations/suggestions?
 

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Lucien Nunes

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USB devices are not normally particularly senstitive to power-derived interference e.g. from earth loops and DC offests created by multiple external power supplies. I build a lot of equipment of a similar nature (not synths but audio/video/computer workstations) and have never had a single problem of this nature, but dealing with interference in mixed analogue/digital systems is one of my specialities.

Presumably when only the second rack is on, it is still connected to the first rack so there is an unbroken ground loop from it to the iMac? Can you give the model and configuration of the eZeus power units - are you using the distribution bus boards?

Are the audio outputs from the rack to the Scarlett balanced? If so, it might be wise to lift the ground of the Scarlett interconnects, which I think will solve the problem. Obviously we should try to find the cause first, as it was not there before, but if the option is there to separate the analogue and digital grounds, that would be worthwhile anyway. If the output is not balanced but is reliably earth-referenced, it might be sufficient to connect the Scarlett input cold leg to the synth output ground, in place of the Scarlett ground.

FWIW my days with analogue synths were those of the VCS3 and Prophet, I wish I had some of that gear now!
 
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USB devices are not normally particularly senstitive to power-derived interference e.g. from earth loops and DC offests created by multiple external power supplies. I build a lot of equipment of a similar nature (not synths but audio/video/computer workstations) and have never had a single problem of this nature, but dealing with interference in mixed analogue/digital systems is one of my specialities.

Presumably when only the second rack is on, it is still connected to the first rack so there is an unbroken ground loop from it to the iMac? Can you give the model and configuration of the eZeus power units - are you using the distribution bus boards?

Are the audio outputs from the rack to the Scarlett balanced? If so, it might be wise to lift the ground of the Scarlett interconnects, which I think will solve the problem. Obviously we should try to find the cause first, as it was not there before, but if the option is there to separate the analogue and digital grounds, that would be worthwhile anyway. If the output is not balanced but is reliably earth-referenced, it might be sufficient to connect the Scarlett input cold leg to the synth output ground, in place of the Scarlett ground.

FWIW my days with analogue synths were those of the VCS3 and Prophet, I wish I had some of that gear now!
Thanks Lucien.

The TipTop uZeus module info is here: μZEUS - Tiptop Audio - https://tiptopaudio.com/uzeus/

It says: The μZEUS mixes linear and switching power technology that can produce up to 2000mA at +12V, 500mA at -12V, 170mA at +5V.

The power supply info is attached in the photo. The product data on the label will make more sense to you than me :)

The issue exists even when the second rack is not connected directly to anything - not even the Scarlett!

This is getting really mystifying now.

So, I tried connecting the Scarlett to my MacBook Pro, and that has no issues. That runs Big Sur.

Interestingly, when I started using my iMac after the Monterey update, my transcription pedal stopped working - and it was doing a similar thing: when I pressed the pedal to start and stop dictation, it would act like a right mouse click - which is similar to this issue, though not exactly the same.

It gets deeper. If I plug the small case into an extension lead that comes from a different wall outlet, no issue. But if I plug it back into an extension lead from the same double outlet (though a different socket), the problem comes back.

Plugging all the Zeus power into an extension from the other wall outlet, the problem goes. Both racks are on, no issue.

BUT - as soon as I plug the Scarlett back in, and patch together both racks, the problem comes back. If only one rack is powered on, the problem is less, but still there.

If I plug the Scarlett instead into the MBP, no problem on the MBP, but the problem is still occurring on the iMac.

To sum up: no matter which outlet the racks are plugged into, as soon as I connect everything together and into the iMac, the problem arises. But it also manifests when the Scarlett is plugged into the MBP, and nothing is plugged into the iMac. If I disconnect the Scarlett, the problem stops.

The only difference between the two computers is the OS. And with the latest update, I got a problem with slightly similar characteristics. In that case I had to buy a newer model of pedal.

I've just tried it with an older Roland Cakewalk UA-25EX, with and without ground lift, and the problem exists - and this is with is being plugged into the MBP, not the iMac.

Why would the iMac be affected in this way? Even with its bluetooth disabled, no joy.

I know this is quite a mess to untangle, but I'm open to all ideas on how this might be fixed.

The craziest thing to me is that prior to unplugging a couple of things and plugging them back in, there was no issue like this with the modular gear or the interface.
 

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Petej999

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I am a musician and use a modular synth in two cases (powered by three uZeus power supplies), which runs into a Focusrite Scarlett sound card, then into an iMac, running the test OS. See attached photo.

I had to take my gear down while I did some work on my desk space. Having put it all back together I powered on my cases, and now my mac's cursor is acting like I am doing lots of right clicks. If I hover over a menu it starts spamming these phantom right clicks.

The uZeus power supplies are plugged into a different 6-way to the mac. This only happens when the eZeuses are on. The more of them I power on, the worse the issue becomes. Everything was fine for months before. I can't see anything I've changed.

Unplugging the Scarlett's USB power stops the issue. So does unplugging the 1/4" jacks from the front. But obviously these are not fixes.

The mouse is a magic trackpad so has no (changeable) batteries. The issue also occurs using a wired mouse - and with no mouse plugged in, and bluetooth turned off.

I have plugged the zeus power supplies into a different wall outlet + extension. No difference.

It even happens when the main (Scarlett-connected) rack is off, but a second rack is powered on, which is not connected to the Scarlett. But if I then unplug the Scarlett from the main rack (which is off), it stops.

There are no other new devices in the house. I live on the end of a block. My only neighbors are decidedly not into tech.

I know of no external works in the neighborhood in the 2-3 days since unplugging everything.

Again, there has been no change that I know of in my home or my immediate area, and everything was working perfectly prior.

Moving the Zeus power supplies into a different socket has made a difference in reducing the spamming of the menus, but not eradicated it.

Any observations/suggestions?
Loose\bad connection somewhere
 

Lucien Nunes

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My current thinking is that one of the 15V adaptors has gone rogue and is outputting HF noise that happens to be at a frequency to which some relevant parts of the computers' I/O logic is susceptible. That would account for why rack 2 PSU can cause a problem even when islanded, but less severe when plugged into a different socket. When the system was out of action for a while, was this the first time the adaptors have been unplugged for a time? If so, or if there is some disturbance to their usual routine, this can trigger dormant problems in SMPSUs.

These power bricks appear to be regular switched-mode PSUs and could be replaced with any 15V supply >2A, although I appreciate if you don't have one lying about you've got to buy it whether it helps or not. Do they have a 2-pin or 3-pin mains inlet and cable? Relevant because we would need to consider the earth path when speccing a replacement.

I expect the uZeus module has a solid connection from its input negative to its output 0V / synth ground. If the bricks have a 3-pin inlet, there might be a path from mains earth to synth signal ground, depending on the internal construction. Some in that power range (30W) have no connection between inlet earth and DC output negative, some have a barrier resistor and some have a solid connection. You could check the resistance with with a multimeter with the PSU unplugged, measuring from the input earth pin to the barrel of the DC jack.
 
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My current thinking is that one of the 15V adaptors has gone rogue and is outputting HF noise that happens to be at a frequency to which some relevant parts of the computers' I/O logic is susceptible. That would account for why rack 2 PSU can cause a problem even when islanded, but less severe when plugged into a different socket. When the system was out of action for a while, was this the first time the adaptors have been unplugged for a time? If so, or if there is some disturbance to their usual routine, this can trigger dormant problems in SMPSUs.

These power bricks appear to be regular switched-mode PSUs and could be replaced with any 15V supply >2A, although I appreciate if you don't have one lying about you've got to buy it whether it helps or not. Do they have a 2-pin or 3-pin mains inlet and cable? Relevant because we would need to consider the earth path when speccing a replacement.

I expect the uZeus module has a solid connection from its input negative to its output 0V / synth ground. If the bricks have a 3-pin inlet, there might be a path from mains earth to synth signal ground, depending on the internal construction. Some in that power range (30W) have no connection between inlet earth and DC output negative, some have a barrier resistor and some have a solid connection. You could check the resistance with with a multimeter with the PSU unplugged, measuring from the input earth pin to the barrel of the DC jack.

I tried downgrading the macOS to Big Sur from Monterey, as my MacBook runs Big Sur and has no issues - but this did not resolve the problem. The only issue seems to be with the iMac.

Why would that be more sensitive than the MacBook? The fact that the MacBook is unaffected would seem to suggest ruling out the power supplies.

I notice that when typing, even with the rack unplugged, powered off and disconnected from the Scarlett, if the Scarlett is plugged into the iMac, the cursor will jump around the screen occasionally, causing me to type into the middle of other sentences.

So here it seems that suddenly the iMac has fallen out of love with audio interfaces. As I think I mentioned, it also misbehaves with an old Roland Cakewalk.

Just for a visual, I recorded a bit of video of the original menu spamming.

I attached some ferrite cores to the power leads of the Zeuses, and this seems to have reduced the behavior a little - but has not eradicated it.

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Lucien Nunes

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even with the rack unplugged, powered off and disconnected from the Scarlett, if the Scarlett is plugged into the iMac, the cursor will jump around the screen occasionally

That puts a different spin on things, pointing towards a fault on the iMac USB ports / controller. And as it varies with electrical conditions it sounds distinctly hardware-based.

As a test, do you have a Thunderbolt dock with a few USB ports that you could use to connect the mouse & Scarlett instead of the iMac's own ports?
 
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this is a test of the issue when typing. this is also a test of writing while all the racs are powered on. try this to cgheck the typin
That puts a different spin on things, pointing towards a fault on the iMac USB ports / controller. And as it varies with electrical conditions it sounds distinctly hardware-based.

As a test, do you have a Thunderbolt dock with a few USB ports that you could use to connect the mouse & Scarlett instead of the iMac's own ports?

Thanks for suggestion Lucien. I do have a little dock, but I am loathe to try it, as the last time I plugged an external hard drive into it, it corrupted the drive and I lost it. That was a few weeks back, some time before all the current mayhem.

I have tried the Scarlett in different USB ports - same result.

I jut spent another hour on the phone with Apple support, and we had no luck. We tried safe mode, and a new user account.

Often, but not always, the problem only arises when the second rack is plugged in. But on the new user account, the problem was wild, and happened as soon as the main rack was plugged in.

So, it will be escalated to the engineers, who will look at some logs and see if they can spot a hardware or software issue. I will update the thread as we proceed.
 
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After spending much of my weekend trying to sort this, including downgrading the mac OS, and trying every reset that Apple has, I again tried different USB ports, and suddenly it worked fine - no glitch - even on the original USB port that was first associated with the issue. The Apple tech said that sometimes these glitches show up in USB ports and sometimes they get fixed with simple resets. But we may never know what really caused this, or what combination of efforts really fixed it. But I appreciate all the comments and advice you guys have shared. Frankly it may take some time to believe it is really sorted!
 

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