Switching power supply regulation repair

[@waltschannel7465]

Rewatching this bc I have a PS that needs fixing. Best, clearest explanation of SMPS on the Net!

[@רועיקאופמן-ע2ב]

Great explanation, the demo is amazing and adds to the understanding

[@manueldi_77]

This high-pitched-sound was a bit of a stress to my ears ;-)

[@12voltvids]

Try living with tinnitus

[@shadetreetrader1135]

Probably the best smps video yet. Great job!! Keep them coming.

[@jamesconway5221]

Hi 12 Voltvids one of the best videos on optocoupler's and testing then you for sure know your stuff and thanks a million for this video it was a fantastic video and the best one I have ever seen to be fair to you, I truly love your videos as they do explain a heck of a lot. I have to say you do know a lot and thanks for sharing your knowledge, for me it could not be better. 😄👍👍👍

[@rameshmondal1179]

Thank you Sir for shearing your valuable knowledge with us. This one is the most helpful video that I have been looking for days to troubleshoot my problems upon switch mode power supply.

[@mrjohhhnnnyyy5797]

The funny thing is that I had a Panasonic CRT TV to repair once, which wouldn't turn on. After a quick investigation, I found a shorted zener diode on the output of the supply and two bone-dry small electrolytics on the primary side. So your story is very true. Nice video!

[@12voltvids]

Yes that is why they added the "crowbar" on the output. That was the era where they had the oscillator operating on the low side of resonance. I had tons of thoe zeners fail due to dry caps on the primary side.

[@karlschwab6437]

Wow! very interesting, this video on how a SMPS works! I was looking for information on how to fix my MFJ-4225MV DC bench power supply that blew its 5a fuse, thermistor and 2 pass transistors! I'll replace these components slowly so I can maybe get it fixed and learn something to boot! Thanks again, Sir.

[@PL00Longa]

Great video! Regarding the panasonics, that is so true. I had an NV-J30 in for repair. It was completely dead. That zener diode kept the output anchored at 0v, which is the same as saying the hot side from powering up. And it was due to the electrolytics. The zener diode (as a sacrificial component) in paralel with the output was a simple, effective solution that actually kept the power supply assembly from destroying itself. Cheers,

[@12voltvids]

That was a design f!!! up. Switching regulator is designed to change the switching frequency to bring the transformer closer to or further out of resonance. At resonance it is most efficient . The idea was to increase the frequency to bring transformer closer to resonance if voltage was low and to drop it if voltage was high. The problem was when caps dried out the frequency went higher,and even though feedback circuit was trying to pull it down it got closer and closer to resonance and thus the voltage kept climbing. Before the aener crowbar was added these VCRs blew up completely. A unit arriving with every chip on the board with hole blown in it. In later designs they moved the frequency above the resonance of the transformer, so as capacitors aged the frequency would go up and move the transformer further away from resonance thus dropping the voltage.

[@nyambemundopu1168]

Hi! You've brought out one of the symptoms of failing SMPS and the probable cause. Well, at least I've learnt that a defective optocoupler could be one of the suspected parts. By the way, kindly tell me the make/brand of the magnifying glass you're using. Thank you.

[@rayhindle642]

Hi.........You always amaze me with your in deapth knowledge of electronics, another of your very educational videos. Thanks for sharing. RayH ( From England )

[@gerardorodriguez5057]

Ok 12 volts,I like how You give Many nformation about other devices, This job is interesting,greetings from Torreón Coahuila México.

[@ventureelect]

Your videos never dissapoint.

[@supercopp6917]

There is always something to learn in your videos. Thank u so much.

[@waltschannel7465]

excellent video, and the full tech school treatment of SMPS. I learned a lot!!!

[@bubblelaber4909]

its always nice watching you fixing.

[@kelirrapaj6462]

Thank you for this video Helps me a lot to understand and to solve my problem

[@rkstr9965]

Good choice of problem and fairly simple SMPS. Also good that you simulated other types of failure modes. It would have been nice to see you bring in the correct 12V's. Even though you can interchange optocouplers there may be enough difference to cause an offset to the voltage control feed back therefore effecting the targeted voltage. I didn't see an adjustment POT on the unit so you may need to use the same part number optocoupler or find a different value reference resistor value.

[@izzzzzz6]

I've been trying to modify a 31.5V 100W rated HP plastic supply which uses an lm358. There are 2 op amps inside that particular package and it's had me really baffled how they have used both of the op amps in this configuration. One side has a Vr but it seems to do nothing, i've tested it for current clamping and wide voltage adjustment but it does nothing (perhaps fine adjustment?). I managed to get V to about 10% down and about 6% up by swapping out one of the resistors for a VR. But i was hoping for more adjustment. Why does it start clicking after i drop the voltage below 26V? Someone mentioned the clicking is arcing. Anyway i'm pretty happy to have gotten some results as i have seen these give 300W at the +6% range possibly more in the ideal volt range. I had 9x 100W LED's light pretty bright from one of these (i just drilled medium sized holes all over the case to improve air cooling).

[@surgingcircuits6955]

Newbie comments. Was glad to see this video (well done, actually explaining "why" things happen) as we have all had switching PS's fail. Thanks for the "how it works" feature in this video. Have been told these are dangerous to work on, and due to not using isolation, they have claimed many scopes. Would have enjoyed a preface on safety before working on these. Another very useful video. Did not enjoy the background music though; distracting - causing me to lose focus several times. Just my 2cents. Thx!

[@12voltvids]

The only reason the music was added at 20db below program audio was because a TV was picked up in the background, and youtube are a55holes for content matching, an dthen hitting the video with a copyright strike. It is amazing how sensitive the detectors are, so I wasn't about to take a chance of getting a hit, as I would have to pull the video.

[@surgingcircuits6955]

12voltvids - No worries. The good far outways. Cheers!

[@12voltvids]

I have other videos describing bench safety, but you are correct. You need to use a "floating" isolation transformer to isolate the hot side from the mains power, and it is a good idea to remove the ground prong from your scope cord, or plug your scope also in to the floating isolation transformer as well. See my isolation transformer demo to see why you need one, and how not all isolation transformers are created equal. If the isolation transformer has a ground prong, you are not isolated. A floating isolation transformer has a 2 prong mains plug, and a 2 prong test outlet. That is why it is called a "floating" design, as the neutral will float, which protects the servicer, as either the hot of neutral side could be pulled to earth and no danger.

[@tonyd1149]

@@12voltvids Thank you so much.

[@khx73]

Nice job Weird high pitched tone behind the video though?

[@12voltvids]

Have no idea where it came from. Was picked up by microphone as it is on the main audio track. Wasn't aparant when I shot it, but I sure heard it once someone noticed it, and went back and looked at the source files. It is there. Have no idea where it came from.

[@Zandraccoon]

Sounds kinda like a CRT power supply. It is possible that it wasn't an audible sound when you recorded it but, magnetic/static interference picked up before the signal got from the mic to the ADC.

[@12voltvids]

It was my scope dyiing. The HV multiplier had started to short, that is why the CRT was so dim. It failed completely a few days later. The microphone was picking up the sound that I didn't hear as it was masked by the sound of the fan in my monitor. Also I tune out those frequencies. I have tinnitus and the buzzing in my ears is very close to the horizontal sweep frequency, so I just ignore it.

[@reacey]

Why would you get less voltage than you are supposed to on the secondary side? I'm getting 4.3 v instead of 12, but it's a steady 4.3v, is this some kind of short on the secondary side? Could it be the regulator transistors on the secondary side?

[@izzzzzz6]

Do the opto's always dead short when they fail? As for the high pitch noise i must be going deaf as i could barly hear it, but it did get me checking my ears for a second.

[@12voltvids]

No they don't. A short is fairly rare. Usually the LED gets weak and thus the unit starts ramping up the voltage. Possibly what happened was the LED was getting weak, and the reference was sensing too low voltage and applying more power to the LED to brighten it up, and that caused the led to pop? Just a guess on my part. Optocouplers have been a relatively reliable part over the years, so this video demonstrates that they do indeed fail, and this is a symptom of that failure. Normally nobody would repair these disposable power supplies. This video was done just to show how they work. If the power supply was embedded on the main board for example, it would have to be repaired. This one came from a PVR, so the power supply was replaced, and I grabbed it to see what went wrong with because I was curious as to what failed. That's why I take apart CFL bulbs, and LED lights ect. Because a diagnostic engineer never stops thinking about device failures. As far as designing things that doesn't really interest me, but when something that was functional breaks, well then it is like being a detective. Instead of figuring out who did it, you have to figure out what did it.

[@izzzzzz6]

Still, great little PSU for certain LED lighting projects

[@12voltvids]

Great idea thanks.

[@NunYa953]

Can a bad opto-coupler cause a surge of voltage that will blow an LED ( and many others in a chain type reaction) on a Samsung LCD TV?

[@suhailasaba1051]

18:28 When 15v zenar gets short & kill everything no current would flow into the circuits of the vcr. Wouldn't shorting the zenar diode result in high currents in any other components of this smps?

[@TheSoundtec]

GREAT VIDEO ! My variac is showing a current draw with no load on the supply so there is a short. The supply has a high pitch whining sound, what would you think the problem is?

[@fly4fun24]

Great video..I have a similar power supply for my recliner, it is 30v 2A when i apply 700ma load the voltage drops to 16 v . Do you have any video on this issue. Thanks

[@lethargicalflux]

Would you recommend changing the power supply for devices if I plan to take them to Europe. I’m moving there, and would like to continue using my AV receiver and subwoofer. Any advice would be appreciated.

[@12voltvids]

Most devices that have a switching power supply will run on 240v buy conventional transformer linear supplies will need to be changed or operated through a 240 to 120 step down transformer.

[@rameshmondal1179]

Sir, I have an SMPS circuit in which two of the primary side filter capacitors blown. As I replace the capacitors and powered up the circuit, the mains fuse keep blowing. I'll be grateful if you point me the direction to solve the problem.

[@12voltvids]

Check the mosfet on the primary side. I did a video a month or so ago showing how to test a mosfet.

[@williamstaten8102]

Cool video. Not sure if I like the music playing though.

[@KingDD83]

I wonder if he put the music in to try to cover up the ~10k tone.

[@redemptusrenatus5336]

There's a crazy annoying high frequency squealing going on in the audio throughout the video. Almost like a dentist drill only higher.

[@redemptusrenatus5336]

Actually, I just put it through a spectrum analyzer on my phone and there's a 10.4 kHz tone but in addition, a higher, 15.7 kHz tone that really squeals.

[@12voltvids]

Have no idea what it is. The sound is definitely there on the source files so it was recorded by the microphone on the camera but I have no clue where it was coming from.

[@manueldi_77]

Maybe from the scope?

[@jimcastillo8950]

what is the brand and strength of your lighted magnify glass on the bench?

[@Okie-Tom]

Very good explanation of the switch mode power supply. I really enjoyed it. One question though. Since voltage was at 11.59 volts and not twelve, was there something you could have changed out to get it up to the 12 volts it was supposed to be?

[@12voltvids]

Remember, the optocoupler was blown. I didn't have the exact part, I had one I pulled from another dead supply, so the spec is likely slightly different.

[@t0nito]

So can you create a variable power supply from 0 to max rated voltage by tweaking the photo transistor side with a variable resistor?

[@12voltvids]

Might be better to do that on the reference IC side, which would change the brightness of the LED in the feedback loop.

[@music4dheartnsoul]

hi sir...thank you so much for this video. do u have video above cctv camera?

[@Synthematix]

hello mate i have a video request! could you do a vid on VFD displays and how theyre powered? ie what voltages and how they actually light up? cheers, paul.

[@SalimAhmad204682]

Very good presentation. Thank you very much.

[@hannonm]

whats the high pitch whine?

[@12voltvids]

The only noise in the background is the fans in my 32" monitor on the wall above my bench that I use as a camera monitor. That's why that TV was given to me. Fans were loud on the old flat panel monitors. It's an old LCD Benq.

[@tonyd1149]

Thank you so much, 12voltvids.

[@HDXFH]

Got a 12 V one that has no output, just Ticks, checked all caps and i suspect the oscillator transistor or optocoupler died

[@old64goat]

Great info, I will be looking to your scope repair.

[@12voltvids]

NEXT!

[@Gary-ts6dh]

Thanks for sharing your knowledge; but, that background music was distracting. Also, you could get closer to your microphone so the echo would be drastically reduced.

[@12voltvids]

microphone is durectly over my head about 6" away.

[@waynegram8907]

I often see circuits that want Unregulated DC voltage, I'm not sure what the benefits are when apply a circuit that wants Unregulated DC voltages. Why would a circuit be "sensitive" to regulated voltages and not work when applying regulated voltages? the circuits will only work with Unregulated DC voltage and NOT regulated voltages, any reasons why?

[@12voltvids]

They have internal linear regulators which require a higher input voltage to work. Give them a stable voltage below their required input and they won't work properly.

[@waynegram8907]

@@12voltvids When circuits use Unregulated DC voltage they don't use internal linear regulators on the PCB board they will supply the components with just Unregulated DC voltage. I'm not sure why some circuit boards will only want unregulated DC voltage and there is no linear regulators IC chips are the PCB board.

[@brig.4398]

I always thought Panasonic vcr was top of the line. Interesting story about the power supplies. I guess they went to a switching supply because of size, weight and cost.

[@12voltvids]

Panasonic made some great machines, but a lot of not so good ones too. As far as VHS machines went JVC and Hitachi were the best built machines. Lot of them are still working after 30 years. At the time we thought of these as cheap machines, but they have stood the test of time.

[@jasejj]

12voltvids The Sanyo Beta machines (specifically the 5x00 series) also stood the. test of time whereas the Toshibas and Sonys of the period are all faulty or expired. The machines that unspooled the tape during wind operations are longer lasting IME.

[@crashbandicoot4everr]

The VTC 5300 (5350 in Greece and Middle East) and the 5400 didn't unthread the tape in stop mode just like the Sony's.

[@jasejj]

The 5100, 5150 and 5000 certainly did though, I have one right here. www.palsite.com/5000ovi.html

[@crashbandicoot4everr]

Jason james Yes. I have a 5000 and a 5350. Sanyo was a bit weird on their model numbers. The higher the number, the older the machine.

[@mrjohhhnnnyyy5797]

I didn't know there's that high pitch noise in the video until I saw bunch of people complaining :) I must've a low-pass filter in my ears :D And I'm 22, supposed to hear over 15kHz. My scope has a dc-dc converter which runs on even lower frequency, now that's what can drive you mad.

[@12voltvids]

I didn't notice it initially when I was editing as I am not cranking it up, and there are lots of other noises around that masked it such as the racket that my computer with it's 7 hard drives, and 3 or 4 cooling fans, it is relatively loud. When it was brought to my attention I put on some headphones and wow, there is was, on the source files too. So I threw on some filters, and uploaded another copy for those with sensitive ears. I didn't remove this one as I don't want to loose revenue that it has already generated. So that's why there is 2 copies online. They are different enough in the sound track that youtube doesn't flag it as a duplicate.

[@vlwilbert]

GREAT VIDEO, JUST WHAT THE DR. ORDERED.KEEP UM COMMING.

[@KingDD83]

Is that ~10khz buzz your scope?

[@quasarhi]

Nice work - explanation and info thankyou!

[@m.emrahozkaya9903]

very nice explanation, thank you.

[@owenthaxter8889]

Great video I learn a lot .

[@robertocisneros1407]

Well explained very educational.

[@saarike]

Nice music and nice work of course. :)

[@12voltvids]

Thanks.

[@dannylightyear3108]

Nice background sound.

[@dannylightyear3108]

Thanks i had the same issue in my tv set.

[@skilledhiko329]

Best explanation thanks

[@josephbuganski8066]

I LOVE REPAIR VIDEOS FROM INTELECTS!!!!!

[@zx8401ztv]

That psu looked quite nice in comparison to the typical junk, the correct input filtering is often omitted, it has an output filter too, not often seen. I dont see many opto couplers fail, its the evil crapacitors (as you said). For switchmode supplys i like the delta electronics psu's, generally quite reliable.

[@12voltvids]

That PSU came from an VDSL modem, so good filtering is essential, as ripple would cause data errors.

[@12voltvids]

I fully expected bad caps. This is the first one I have seen fail like this, with the LED side shorting.

[@aquarius2435]

thanks ,very useful video,hope you can fix your scope :-)

[@FennecTECH]

The spike in this video is at 10474 Hz just notch filter that down to 1

[@markanderson350]

I can hear it whistling, drives me nuts and I am 56

[@umajunkcollector]

The main thing is that it converts 60z to a much higher freq to put through a SMALLER CHEAPER TRANSFORMER, since higher freqs are more efficient on transformers. Then the secondary must filter high freq instead of 60z. Higher freqs can cause RFI. Plus the safety devices can go bananas. They must take more precautions than linear since switchers are often used to recharge lith ion batteries. Don

[@12voltvids]

Right, cost is one factor, but efficiency is the main reason they do it. Governments have mandated certain efficiency levels, and switching supplies convert more energy and produce less heat than linear transformers. Linear power supplies are 40 - 60% efficient at best. I am not just talking about the transformer efficiency either, I am talking about the entire supply, with the linear regulator that burns off excess power as heat. Very wasteful. Switching supplies on the other hand are 90% some as high as 95% efficient which is a huge difference.

[@umajunkcollector]

this is true, they have their advantages. But they seem more likely to fail, but usually the fail is cheap to fix. Most folks toss them, more for the landfills. I have a bunch of failed ones that are sealed shut. Funny thing, the fail is often bad cable connections or jacks LOL

[@tonycosgrove6433]

Very interesting video good work.

[@FennecTECH]

If you cannot eliminate the source download a program called audacity and cut out the peak at the top of the scale

[@12voltvids]

Sorry they don't pay me enough to demux the audio, process it, and remux it.

[@FennecTECH]

i did it for you took about five minutes

[@FennecTECH]

mega.nz/#!bEJTSBzZ!C93CssnKcrS3bO1blqhPz0NbKHIN0OfBthOOnLOZjKs

[@FennecTECH]

if you like youtube creator studio has the facility to replace your audio with this one

[@12voltvids]

The problem is if I re-upload it, I loose the stats, and any money generated by the current views. there is NO WAY to replace the sound track on an existing video other than use KZbin creator studio and replace it all with music. This has been very well documented as many have already posted that question, and it can't be done.

[@crashbandicoot4everr]

And now I know why my 1986 National Panasonic VCR just smoked when I plugged it in and the whole house smelled burning...

[@12voltvids]

They don't call them voltage to smoke converters for nothing.

[@crashbandicoot4everr]

I recently got my hands on a rare multi system Sanyo Betamax from 1981 and it actually uses an SMPS. Sometimes, I can hear a humming noise comming from the power supply. I guess it needs a recap right?

[@12voltvids]

Yes and I would do it before using it because it could blow and overvoltage the rest of the machine. Some of those early SMPS did not have over voltage protection, and one day you head a pop and a bunch of smoke comes out. Then it is too late.

[@crashbandicoot4everr]

So, does this apply to SMPS manufacturers other than Panasonic too? Do you know where I can find the schematic for this machine? It's a VTC 9455 and I can't find anything on the whole internet!

[@IS-77]

Well explained ,thanks

[@jjohnson71958]

Interesting diagram

[@rickyjayram5384]

great job

[@alanbolek4364]

Great Video!

[@dannylightyear3108]

My tv set is a philips from 2010

[@fododude]

Man, that circuit board glue looks so terrible.

[@jerryspann8713]

Panasonic should have never put switching power supplies in their VCR's.

[@TheJavaSync]

nice, but some TVs PSU more complicated .. :'(

[@12voltvids]

TheJavaSync This gives the basics which all switch mode supplies use. TV psu has additional circuits and generally multiple supplies. Stand by main circuit and backlight. They also have power factor correction.

[@roshan1567]

Nice job

[@annierenard5954]

thank you

[@bililast705]

Nice video.

[@BlankBrain]

If your speaker is a thumpin' and there's nothin' on the wire, try some warfarin in your woofer; it's what the rats desire.

[@12voltvids]

Its the Sony receiver. Starting to act up again.

[@fulwell1]

Is that the source of the high pitched squeal? Sounds to me as though it is voltage or load dependent as it is not continuous/stable.

[@afzaalkhan.m]

Starting sounds are very jarring pls do rectify.

[@12voltvids]

Too bad so sad my scope was making a bunch of noise that was picked up by the mic.

[@Radek__]

15:30 please stop touching that optocoupler. The board is under the voltage. What the hack? :) You don't have 3 lives and 1credit as we have in arcade games :) I've noticed few times on the other videos -when you explain something, you always touching elements on the borad - don't do it ;)

[@12voltvids]

Everything I work on is plugged into an isolation transformer, so I am not going to receive a shock because the line is isolated. The worst that could happen if I put my finger across the primary side is a mild shock. I also keep my free hand away from the live circuit so no chance of current across my heart. The worst shock I ever received was from an operating microwave oven. 2300 volts at about 700 mA which is a lot. The tool I was using the insulation had failed and my hand clamped down on the tool so hard I couldn't let go. I had to jump back to break the connection. Again, no harm done, following electricians rule, only 1 hand and other hand in back pocket. It may look like I am taking risks, but I can assure you I am a journeyman electrician (in my current job even though these days it is mostly fiber optics I work with I am still working close to utilities) I take no risks whatsoever. Also it may look like I am touching live circuits on camera, when in fact I am pointing at something, but with the 2 dimension view of the camera it looks like I am closer to live circuits than I actually am.

[@Radek__]

oh, is not like that. I admire your skills, experience and knowledge. I saw most of your videos, you are very brave during fixing high-voltage things when they are stay live. I remember one video titled “Most Dangerous TV fault ever” I was scared when I saw how you're touching and shaking high voltage capacitor and have fun with huge arc sparks - I envy you that you can do it easily. I would throw it down immediately then run away at least 2meters from it and trying to calm down. High voltage is for me something like spiders for other people. They know that nothing bad can't happen but they are scared anyway. Today I saw your video “Build a current limiter for safe testing” I'm grateful for sharing that idea, and for that you've explained why and how it works. On that video, you took cord cable and you make short-circuit easy on TV's high voltage side to demonstrate how current limiter tool works. I was scared again :) I have good experience in electronics repairs (laptop motherboards, smd, bga, etc) but I avoid high voltage units, power supplies, etc. But because of you I finally understand more about those things which always scared me. Always when I have LCD/LED Tv for repair, I'm watch your videos as help/lesson. So you are an authority (expert) for me in everything where high voltage is. (microwaves, TV and tube amplifiers repairs, old units, psu, etc.) And I guess that you are high experienced electrician engineer. Few times I heard on your videos that you are using isolation transformer. Because of you I've learned what it is :) But on the polish sites, I've read that if you connect few devices/units to one isolation transformer then risk of danger is grater. So ideal condition is one device/unit per one transformer. Is it true or unnecessary bullshit? Greetings from poland.

[@zoubirdjelouah3273]

Good

[@Mtaalas]

Kids... don't hit your measuring devices... for real...

[@thakholidornald2818]

This is Godly......

[@johnohara54]

Got me confused; you always talk about how dangerous aswitched mode PS is then you short it out to prove a point. Then you talk about emitter base side of opto-coupler then diode side; how about “ input” and “output” side would be clearer and less confusing. You lost me . Only 12 volt output; I though5 purpose of SMPS supply was efficient high voltage source. Confusing,confusing.

[@12voltvids]

The primary side of the transformer has high voltage. About 170V in 120V countries and about 360V in 240v countries. That is what is present on the main filter capacitor, and switching transistor on the primary side. The secondary side is 12 volts. The opto coupler optically isolates the 2 sides. You need to use an isolation transformer to safely work on these things and when the main primary filter capacitor is charges it can bite you pretty good if you stick your fingers in there when it is charged up.

[@FennecTECH]

I cant stand the high pitched squeal in the background sorry fix that and im in

[@12voltvids]

low pass filtered version should be live in a few minutes.

[@FennecTECH]

its not a low pass filter i actually used a notch filter to pull out he two spikes

[@12voltvids]

I know what a notch filter is. I just couldn't be bothered using one, because I have to apply to each clip separately, and there are many clips. Every camera cut is multiple clips as I cut out gaps and pauses during the record session. So I just threw on a low pass filter in my editing software and rendered it out again. The low pass filter is only on the camera audio, not the background music, which is something like 30dB down

[@FennecTECH]

sadly i can still hear it in your video instaid of putting the notch filter on each clip why not just pit on in post production (ie to the fianal video)

[@12voltvids]

That would require demux and re-compress, which would result in a degraded picture, so the only solution is to roll off the high frequency and re-encode the file. So I set the roll off this time to 6KHz so there should be nothing by 10KHz in the voice track. Still trying to figure out where the noise was coming from, but I suspect it was my scope dying that was kicking out noise. I don't hear it unless I put the cans on because there is so much noise here in my edit bay as right outside my window is the HVAC system and it is running pretty much full time to heat the house as it is the dead of winter here, so it masks the sound, but with the cans on I can hear it. New version should be up in a few minutes for those with sensitive hearing.

[@drteeth7054]

Background music is totally unnecessary and most annoying.

[@12voltvids]

Was added to drown out the flyback noise from the scope that was in the process of failing. It created a whistle and drew much fire from people that were annoyed by it.