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Post by johneppstein on Jul 16, 2019 19:41:36 GMT -6
You can go the pro route and install the low voltage units that have remote power supplies. Then the bulbs don't have noise issues. But the power supply still might.
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Post by johneppstein on Jul 16, 2019 19:47:12 GMT -6
I've got both recessed LEDs and installed strips. No problem with switching noise. Besides, switching noise problems have always been overblown in the studio world talk, and any instance could likely be traced back to a wiring/installation issue. Er, no. I've had a number of computers and other switching powered devices that had definite RFI problems. Computers also sometimes leak RFI off of video cards and cables.
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Post by svart on Jul 16, 2019 21:06:28 GMT -6
I've got both recessed LEDs and installed strips. No problem with switching noise. Besides, switching noise problems have always been overblown in the studio world talk, and any instance could likely be traced back to a wiring/installation issue. Er, no. I've had a number of computers and other switching powered devices that had definite RFI problems. Computers also sometimes leak RFI off of video cards and cables. It's usually ground loops. Almost all my computers have needed disassembly and sanding of ground connections between panels and such. Most cheap cases use a waxy stamping lube that leaves a high ohmic connection between the cards, panels and connections. Fixing the ground had always fixed the RFI. Same for house wiring. Usually the issue is poor ground and neutral matching so current leaks along the ground conductor. Source: I'm an RF engineer.
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Post by jeremygillespie on Jul 16, 2019 21:27:07 GMT -6
I’ve got no dog in this argument cause I’ll admit I don’t know much on the subject. But... a few years back I racked up some vintage modules and had an awful noise problem with them. Couldn’t figure it out so had my tech look at it (with my tail between my legs). He traced it to my phantom power supply and put in a linear instead of switching and the noise went away. 🤷🏻♂️
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Post by svart on Jul 16, 2019 22:17:26 GMT -6
I’ve got no dog in this argument cause I’ll admit I don’t know much on the subject. But... a few years back I racked up some vintage modules and had an awful noise problem with them. Couldn’t figure it out so had my tech look at it (with my tail between my legs). He traced it to my phantom power supply and put in a linear instead of switching and the noise went away. 🤷🏻♂️ Before I was an RF designer, I designed switchers.. Yes, they can be noisy, but as I mentioned, it's usually a case of them being misused, mis-specified, or improperly applied, and there's always an underlying reason why you get noise. Majority of the time it's due to poor grounding which allows the noise currents to float over ground. Unfortunately, they're also somewhat more complicated to troubleshoot as there are more failure modes to consider, so most folks stop short and just blame the supply and do what your tech did and swap it out. And then you get all the anecdotes about switchers in forum threads about how noisy they are, and everyone agrees and years on the myth persists. But the truth is, they're in everything. Everything from your TV to your phone, to your audio interface, some preamps, and in the majority of cases they work perfectly. It's usually these edge cases where someone racked up some modules and used a switcher with a large ripple(poor spec or needs external filtering), either too light or too heavy of a load which causes pulse skipping safety modes to trigger, or the ground is not good enough and you get ground currents all over everything. In fact, I use some switching supplies in my day job that are quieter than linear supplies..
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Post by jeremygillespie on Jul 17, 2019 5:33:40 GMT -6
I’ve got no dog in this argument cause I’ll admit I don’t know much on the subject. But... a few years back I racked up some vintage modules and had an awful noise problem with them. Couldn’t figure it out so had my tech look at it (with my tail between my legs). He traced it to my phantom power supply and put in a linear instead of switching and the noise went away. 🤷🏻♂️ Before I was an RF designer, I designed switchers.. Yes, they can be noisy, but as I mentioned, it's usually a case of them being misused, mis-specified, or improperly applied, and there's always an underlying reason why you get noise. Majority of the time it's due to poor grounding which allows the noise currents to float over ground. Unfortunately, they're also somewhat more complicated to troubleshoot as there are more failure modes to consider, so most folks stop short and just blame the supply and do what your tech did and swap it out. And then you get all the anecdotes about switchers in forum threads about how noisy they are, and everyone agrees and years on the myth persists. But the truth is, they're in everything. Everything from your TV to your phone, to your audio interface, some preamps, and in the majority of cases they work perfectly. It's usually these edge cases where someone racked up some modules and used a switcher with a large ripple(poor spec or needs external filtering), either too light or too heavy of a load which causes pulse skipping safety modes to trigger, or the ground is not good enough and you get ground currents all over everything. In fact, I use some switching supplies in my day job that are quieter than linear supplies.. As I remember I probably cheaped out on the switching supply and then was frustrated when that was the problem haha.
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Post by svart on Jul 17, 2019 7:25:33 GMT -6
Before I was an RF designer, I designed switchers.. Yes, they can be noisy, but as I mentioned, it's usually a case of them being misused, mis-specified, or improperly applied, and there's always an underlying reason why you get noise. Majority of the time it's due to poor grounding which allows the noise currents to float over ground. Unfortunately, they're also somewhat more complicated to troubleshoot as there are more failure modes to consider, so most folks stop short and just blame the supply and do what your tech did and swap it out. And then you get all the anecdotes about switchers in forum threads about how noisy they are, and everyone agrees and years on the myth persists. But the truth is, they're in everything. Everything from your TV to your phone, to your audio interface, some preamps, and in the majority of cases they work perfectly. It's usually these edge cases where someone racked up some modules and used a switcher with a large ripple(poor spec or needs external filtering), either too light or too heavy of a load which causes pulse skipping safety modes to trigger, or the ground is not good enough and you get ground currents all over everything. In fact, I use some switching supplies in my day job that are quieter than linear supplies.. As I remember I probably cheaped out on the switching supply and then was frustrated when that was the problem haha. I think it's important that people know that SMPS have caveats to their usage, which you might have found out the hard way. Not all SMPS are suitable for the tasks people want them to be used for unless care is taken to work around the shortcomings. They excel at saving power, at the expense of cost and complexity in design and implementation. Linears have drawbacks of being extremely inefficient which result in large amounts of power wasted as heat, but they're more forgiving in implementation and application. I guess what I'm saying is that the notion of SMPS being "noisy" is quite a pervasive one, but it's almost always an application or implementation issue that allows them to be noisy in a certain situation.
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Post by EmRR on Jul 17, 2019 21:50:38 GMT -6
I’ve got no dog in this argument cause I’ll admit I don’t know much on the subject. But... a few years back I racked up some vintage modules and had an awful noise problem with them. Couldn’t figure it out so had my tech look at it (with my tail between my legs). He traced it to my phantom power supply and put in a linear instead of switching and the noise went away. 🤷🏻♂️ some audio analysis of popular switchers linked here: www.proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=1123Some work fine as-is, some need extra support circuits, etc.....
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Post by cyrano on Jul 23, 2019 20:30:11 GMT -6
Obviously, you'll have a bit of experimenting to do. LED's don't have a linear curve, so you need to find the bottom and top of the range. Nothing much happens under 1,5V and going over 3,5V won't yield more light, but will reduce lifespan. And these numbers vary by color and standard/high efficiency LEDs.
My simple way to do this (presuming an existing controllable power source) is by using a standard linear pot, setting the bottom, measuring the value of the pot, then adding a resistor. Likewise for the top.
A current controlled power source will be easier.
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Post by BenjaminAshlin on Jul 24, 2019 5:13:29 GMT -6
Go the DIY route and use a DC power supply. Easily dimmable by using a PSU you can control the voltage or current of. No interference from the LEDs and the wiring and you can stuff the power supply where it's far enough from sensitive wiring/gear. I've seen some pretty lousy builds in constant current LED drivers. And it's not price related... HMmmm. Have you actually tried that? I don't have experience with LED dimming, but most lighting dimmers I know of control the light by altering the duty cycle of the AC, not the amplitude of the voltage. That would lead me to think that an LED dimmer would be contolling the duty cycle of pulsed DC.
Don't LEDS have a fairly narrow range of voltages they respond to?
I'm asking because I don't know.
Thats correct. Many LEDs turn off before they go dim enough.
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Post by Omicron9 on Jul 24, 2019 7:10:15 GMT -6
Thanks for all the info and considerations, gentlemen. Both helpful and appreciated; please keep it all coming. Your partially-unlit friend, -09
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Post by svart on Jul 24, 2019 17:56:34 GMT -6
Obviously, you'll have a bit of experimenting to do. LED's don't have a linear curve, so you need to find the bottom and top of the range. Nothing much happens under 1,5V and going over 3,5V won't yield more light, but will reduce lifespan. And these numbers vary by color and standard/high efficiency LEDs. My simple way to do this (presuming an existing controllable power source) is by using a standard linear pot, setting the bottom, measuring the value of the pot, then adding a resistor. Likewise for the top. A current controlled power source will be easier. LEDs are indeed current driven devices. The way to dim LEDs is to turn them on and off very quickly so that their on-state currents are always in full conduction, but their duty cycle is variable, so the longer they stay on, the brighter our eyes perceive them and vice versa. This is called PWM or pulse width modulation. The true dimming bulbs have a feedback that changes this duty cycle with input voltage so they dim when the dimmer reduces the AC line voltage.
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Post by cyrano on Jul 25, 2019 17:06:06 GMT -6
svartOf course, but PWM can be noisy. And hard to filter. I tried DC, for a "studio" that has dozens of vintage synths around. Thousands of interconnecting wires everywhere. Mostly unbalanced wiring. Unshielded cases. Power transformers everywhere... Worked well enough. I spent days there finding sources. The owner had already eliminated all the SPSUs (wall-warts) he could find but that didn't do much for the noise. And since it was intermittent, it was driving him crazy. He hadn't found the noisy LED lighting in the ceiling since he figured these were 12V halogen bulbs. And someone on the net had convinced him halogen bulbs can't be noisy. The main culprit was mains wiring, tho. Dozens of extension cords. Neon bulbs in switches, some wired in reverse. Some without ground... Some synths had dried out caps in the PSU. That made them pick up more noise too.
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Post by Guitar on Jul 25, 2019 21:20:54 GMT -6
I cheaped out, apparently, and have a long strip of LED's running around the perimeter of my ceiling, they stick on. Soldered two of them together, and they are powered with a 4 Amp laptop power supply I had on hand. I haven't tried a dimmer, they are already dim enough for me I guess. This was a very inexpensive setup. I've really gotten used to it over the past few years. In a way it reminds me of a casino or a theater or something. All my bulbs and lamps are LED as well. It's a good vibe.
I don't know nearly as much as everyone else seems to about what I assume is construction work, which is kind of fascinating to me. Something to learn more about I guess.
No noise here either.
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Post by svart on Jul 26, 2019 6:25:02 GMT -6
svart Of course, but PWM can be noisy. And hard to filter. I tried DC, for a "studio" that has dozens of vintage synths around. Thousands of interconnecting wires everywhere. Mostly unbalanced wiring. Unshielded cases. Power transformers everywhere... Worked well enough. I spent days there finding sources. The owner had already eliminated all the SPSUs (wall-warts) he could find but that didn't do much for the noise. And since it was intermittent, it was driving him crazy. He hadn't found the noisy LED lighting in the ceiling since he figured these were 12V halogen bulbs. And someone on the net had convinced him halogen bulbs can't be noisy. The main culprit was mains wiring, tho. Dozens of extension cords. Neon bulbs in switches, some wired in reverse. Some without ground... Some synths had dried out caps in the PSU. That made them pick up more noise too. It's almost always the wiring. PWM for small household lights is usually much too high in frequency to cause issues. The higher the PWM frequency, the smaller the inductors and caps in the power supplies can be, and therefor cheaper, so small and cheap are the norm with the side benefit that the frequencies are well outside the audio band. They're usually running in the hundreds of KHz and into the MHz, which means the harmonic content of the PWM signal is much higher than that. Fluorescent lights with transformer ballasts are much worse than LEDs since they resonate at 60Hz and their harmonic noise is right within the audio band.
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Post by svart on Jul 26, 2019 6:46:36 GMT -6
older halogen/incandescent dimmers used phase angle to dim. They'd exploit that the filaments in the bulbs had a specific amount of time to heat and cool, and would "turn off" the AC signal for a period of the 60Hz signal (noted in portions of the 360 degree cycle). The AC would be on for a variable amount of time but the filament would average out the power.
They use a DIAC (which is like a dual, anti-parallel diode with a voltage threshold) and a TRIAC (which is like a diac with a gate pin). The AC voltage is fed through a potentiometer to a capacitor and that node is fed to the diac. Using the pot to adjust the amount of AC, the cap is charged until the voltage triggers the diac, which in turn trigges the triac to turn on, and AC flows through the load. The triac conducts until the AC crosses zero volts and then turns off until the next cycle reaches the threshold voltage again.
So old style triac dimmers would chop up the 60Hz signal at odd phase angles which mean that the harmonics would not only be in the audio band, but somewhat variable in frequency too depending on what loads were attached.
I designed one of these many years ago for an industrial company that built temperature adjustable heating elements for leather branding.
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Post by Omicron9 on Dec 5, 2019 8:20:31 GMT -6
Lutron makes some really good dimmers for LED's. (About $50 a pop or so) You want to make sure your LED arrays are dimmable, then use the Lutron's and it's all good. DO NOT use standard in the wall dimmers for incandescents. Dr. Bill and others: I'm resurrecting this thread. When I first posted, I was still doing the research. Now I've installed the in-ceiling LED recessed lights. These have the outboard power supplies, are dimmable, and feature a 5-way color temp switch. Very bright and I'm digging them. Also brings a great look and vibe to the studio. I had my electrician install a Lutron dimmer (~ $35.) which was designed for LEDs, and my LED light manufacturer listed this model as compatible with the model I have. All good so far. The dimmer was working great; excellent degree of granular control over the lights and no audible buzzing. Happiness abounded. However. Once I got all the gear moved in/cabled/wired and did some signal-pass testing, there was a most unwelcome loud buzz in all tracks. Oh most unwelcome indeed. Adjusting the dimmer had an effect on the buzz-hum. Flipping the dimmer off killed the buzz-hum entirely. I swapped out the Lutron dimmer with a garden-variety bog-standard on/off switch. Lights on; buzz-hum entirely gone. Problem solved! Except that these lights are super bright at full power, so I still need a dimmer. Or sunglasses. I've done some reading/research on this, and I see things like "to avoid buzz and hum, install a high-grade dimmer." Of course none of the articles have stated exactly what is/where to find such a high-grade dimmer. Ergo, I ask your help. Has anyone installed an LED dimmer that doesn't cause buzz-hum in your signal path? Exceedingly mondo thanks in advance, -09
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Post by svart on Dec 5, 2019 8:41:17 GMT -6
Lutron makes some really good dimmers for LED's. (About $50 a pop or so) You want to make sure your LED arrays are dimmable, then use the Lutron's and it's all good. DO NOT use standard in the wall dimmers for incandescents. Dr. Bill and others: I'm resurrecting this thread. When I first posted, I was still doing the research. Now I've installed the in-ceiling LED recessed lights. These have the outboard power supplies, are dimmable, and feature a 5-way color temp switch. Very bright and I'm digging them. Also brings a great look and vibe to the studio. I had my electrician install a Lutron dimmer (~ $35.) which was designed for LEDs, and my LED light manufacturer listed this model as compatible with the model I have. All good so far. The dimmer was working great; excellent degree of granular control over the lights and no audible buzzing. Happiness abounded. However. Once I got all the gear moved in/cabled/wired and did some signal-pass testing, there was a most unwelcome loud buzz in all tracks. Oh most unwelcome indeed. Adjusting the dimmer had an effect on the buzz-hum. Flipping the dimmer off killed the buzz-hum entirely. I swapped out the Lutron dimmer with a garden-variety bog-standard on/off switch. Lights on; buzz-hum entirely gone. Problem solved! Except that these lights are super bright at full power, so I still need a dimmer. Or sunglasses. I've done some reading/research on this, and I see things like "to avoid buzz and hum, install a high-grade dimmer." Of course none of the articles have stated exactly what is/where to find such a high-grade dimmer. Ergo, I ask your help. Has anyone installed an LED dimmer that doesn't cause buzz-hum in your signal path? Exceedingly mondo thanks in advance, -09 I haven't worked designing dimmers for years now so I don't know what the difference between an "LED" capable model and a non-LED capable model is, but the dimming action is done to the AC directly in the old style which caused backfeeding of the chopping noise onto the whole AC circuit. The best option would have been to isolate the lighting onto it's own circuit to the breaker box. I suggest a low-tech option.. Something used in the film industry called "ND Gel". It's a sheet of translucent plastic that reduces the amount of light through it, but without changing the color temperature. It's very much like car window tinting but specifically designed to not change color components. It comes in all kinds of strengths and it's pretty cheap. A sheet would do all the lights you have. In my studio I use something similar called "1/8 CTB" which shifts the color of light towards blue by removing yellow. This way I change rather yellow-ish LED lights into bright white output since the color temp I want is not really available. I cut out little circles that have ears and I stuff the ears between the body of the lamp and the lens to hold the CTB in place. Not terribly professional but it works and you can't really see it.
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Post by drbill on Dec 5, 2019 9:55:59 GMT -6
Lutron makes some really good dimmers for LED's. (About $50 a pop or so) You want to make sure your LED arrays are dimmable, then use the Lutron's and it's all good. DO NOT use standard in the wall dimmers for incandescents. Dr. Bill and others: I'm resurrecting this thread. When I first posted, I was still doing the research. Now I've installed the in-ceiling LED recessed lights. These have the outboard power supplies, are dimmable, and feature a 5-way color temp switch. Very bright and I'm digging them. Also brings a great look and vibe to the studio. I had my electrician install a Lutron dimmer (~ $35.) which was designed for LEDs, and my LED light manufacturer listed this model as compatible with the model I have. All good so far. The dimmer was working great; excellent degree of granular control over the lights and no audible buzzing. Happiness abounded. However. Once I got all the gear moved in/cabled/wired and did some signal-pass testing, there was a most unwelcome loud buzz in all tracks. Oh most unwelcome indeed. Adjusting the dimmer had an effect on the buzz-hum. Flipping the dimmer off killed the buzz-hum entirely. I swapped out the Lutron dimmer with a garden-variety bog-standard on/off switch. Lights on; buzz-hum entirely gone. Problem solved! Except that these lights are super bright at full power, so I still need a dimmer. Or sunglasses. I've done some reading/research on this, and I see things like "to avoid buzz and hum, install a high-grade dimmer." Of course none of the articles have stated exactly what is/where to find such a high-grade dimmer. Ergo, I ask your help. Has anyone installed an LED dimmer that doesn't cause buzz-hum in your signal path? Exceedingly mondo thanks in advance, -09 All I can do is suggest 2 things. 1. To make sure the lighting is on a different circuit than your audio. 2. What I mentioned earlier : "Lutron Maestro. C-L Dimmers. Got em from a lighting place - not Home Depot. Beyond that, a knowledgeable electrician is your best bet. I know little, and only did what those who know much more than me told me to do. Good luck!!
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Post by stormymondays on Dec 5, 2019 11:26:30 GMT -6
By the way, for those of you that have Philips Hue systems, sometimes the power supply itself makes a high pitched noise. I think it’s called “coil whine”. I’ve had that happen on their new “play” model, only on some full power settings.
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Post by swafford on Dec 5, 2019 11:49:04 GMT -6
I suggest a low-tech option.. Something used in the film industry called "ND Gel". It's a sheet of translucent plastic that reduces the amount of light through it, but without changing the color temperature. It's very much like car window tinting but specifically designed to not change color components. It comes in all kinds of strengths and it's pretty cheap. A sheet would do all the lights you have. FYI "ND" stands for "neutral density." If it's a true neutral density gel, it will pass all wave lengths of light at a specified reduced intensity and because it is engineered with those specifications, can be quite expensive. You can purchase other kinds of gels that are 'neutral' and designed for stage lighting that would have the same affect (ie reducing light transmission, but not necessarily equal wavelengths nor at specific percentages) and cut them to size.
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Post by svart on Dec 5, 2019 12:15:59 GMT -6
I suggest a low-tech option.. Something used in the film industry called "ND Gel". It's a sheet of translucent plastic that reduces the amount of light through it, but without changing the color temperature. It's very much like car window tinting but specifically designed to not change color components. It comes in all kinds of strengths and it's pretty cheap. A sheet would do all the lights you have. FYI "ND" stands for "neutral density." If it's a true neutral density gel, it will pass all wave lengths of light at a specified reduced intensity and because it is engineered with those specifications, can be quite expensive. You can purchase other kinds of gels that are 'neutral' and designed for stage lighting that would have the same affect (ie reducing light transmission, but not necessarily equal wavelengths nor at specific percentages) and cut them to size. I've used ND gel sheets for years in video/film work, I know all about it.. The ND gels aren't that expensive. I have tubes full of various ND and other gels. ND glass filters for cameras ARE crazy expensive though, but those are held to a different standard.
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Post by Omicron9 on Dec 5, 2019 13:05:06 GMT -6
Thanks, Svart. Thanks, Dr. Bill. I have a call in to my electrician re: different circuit. And I did find the Maestro CL dimmer at Home Depot and amazon; will try that first.
Again, highly appreciated. I really like what a friendly, helpful community this is. Unlike some other forums <cough>purple<cough>.
Regards, -09
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Post by swafford on Dec 5, 2019 13:17:06 GMT -6
FYI "ND" stands for "neutral density." If it's a true neutral density gel, it will pass all wave lengths of light at a specified reduced intensity and because it is engineered with those specifications, can be quite expensive. You can purchase other kinds of gels that are 'neutral' and designed for stage lighting that would have the same affect (ie reducing light transmission, but not necessarily equal wavelengths nor at specific percentages) and cut them to size. I've used ND gel sheets for years in video/film work, I know all about it.. The ND gels aren't that expensive. I have tubes full of various ND and other gels. ND glass filters for cameras ARE crazy expensive though, but those are held to a different standard. And I worked in the commercial photographic industry for 35 years as a drone, photographer and consultant. But, as we both know, not everyone has that kind of experience. The expectation for color and luminosity absorption of the gel vs. glass is the same, the huge price difference is due to glass needing to pass image forming light. And I'm guessing that gray stage gels are cheaper then ND gels.
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Post by johneppstein on Dec 5, 2019 15:55:51 GMT -6
Make sure your power supply isn't defective. Sometimes a factory lets a dud slip through.
Semi-frequently one encounters a switching supply that develops a buzz after having been dead quiet. This usually is caused by one or more of the noise filtering caps failing. A similar thing could happen straight out of the factory if they had a bad part or if a solder joint was defective.
The thing about a switcher developing a bad filter is that, unlike in a linear, it usually doesn't affect the operation of the supply as a supply - the output voltages are still OK and it won't blow fuses; it just gets noisy.
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