Philips Soundbar - Design Fault? | Can I fix it?

A long time subscriber sent me a Philips sound bar to have a look at. He bought a job lot of 25 of them, and they all have the same fault. They overheat after about 15 minutes and start cutting out.
The person he purchased them from, had a container full of them, all with the same fault too!
He tried changing the amplifier chip on one, and it didn't make any difference.
Design problem? Wrong Component fitted?
Let's see if we can figure out a way to get them working again.
I'm not an expert, but I do enjoy trying to fix things.
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#electronicsrepair #electronics #repair
Philips sound bar repair
Philips sound bar overheating
Philips sound bar cutting out
Philips sound bar fix
Faulty Philips sound Bar

[@RaduTek]

It's surprising how design defects like these manage to make their way out of R&D departments to the production line and retail. Great job explaining the way the Class D amp works and how to fix it. Probably going to save a lot of these from becoming e-waste.

[@BuyitFixit]

Thank you 🙂👍Yes hopefully it might help others with the same problem.

[@Sydney268]

Yeah I was thinking that, the design must have worked at some point?!

[@BuyitFixit]

I think the problem only starts showing when at loud volume after about 15 or 20 minutes.

[@Sydney268]

@@BuyitFixit sure but one of the first tests I'd do is full power for an hour or so to see how hot it got - come on Philips R&D

[@RaduTek]

@@Sydney268 Yeah like they need to test it at full volume for a long period of time to make sure nothing fails or malfunctions. Unless they don't care about the longevity of their product, which nowadays is sadly becoming the norm.

[@GapRecordingsNamibia]

They did indeed try to implement a hybrid filter, problem is, when doing that you need to calculate the components to deal with the 2x the maximum output voltage and also the current and that is only for starters, if you look at an RC snubber for a power relay you'll see it is very similar the problem is, even those resistors were totally under speced for the output circuit being driven under modulation, for the basic power rating of the amp it would most probably have been ok, typically, this is referred to as a Zoebel network, and should be designed so that the amp is kept 'stable'........ But, this was inadequate, when combined with modulation..... Very well done sir, another brilliant video!

[@BuyitFixit]

Thank you, and thanks for the info 👍

[@d614gakadoug9]

The filter network is not required for amplifier stability. It is required to control EMI/RFI. If the connections to the speakers were very short the filter could be as simple as a couple of ferrite beads and small capacitors to deal only with very high frequencies. The inductance of the speakers themselves would be the major "smoothing" components. Long connecting wires act as radiating antennas so the high frequency components due to the switched voltage at the amp outputs must be kept off the wires.

[@MichaelBeeny]

The application notes were for 8-ohm speakers, but 4-ohm speakers were used in the product. This would explain the different inductor value. Strangely the circuit diagram showed the capacitor and inductor being the same for both 8 and 4 ohms, clearly incorrect. The resistors that burned was part of the Zobel network in series with the capacitor. It probably burned because the filter was connected incorrectly. I assumed you replaced them, probably about 10 ohms. Its function is to keep the amplifier stable. The output inductors do tend to run warm, but of course not as hot as they were. I doubt the amplifier puts out more than about 10 watts with only 15 volts input. Well done in sorting it out.

[@BuyitFixit]

Thanks Michael 👍Yes I replaced the resistors but the inductors still got hot. I've not really done anything with class D amplifiers before so it's all new to me. I'll have to look up Zobel network. Thanks for commenting 🙂

[@d614gakadoug9]

Yes, I had a look at the data sheet and noticed the filters were the same when the text was clearly implying they would be different. The filters are purely for EMI/RFI control and necessary because the connections to the speakers are long.

[@Denis7947.]

​@@BuyitFixityou can try to put a small fan to cool them down

[@BuyitFixit]

@denisstefan2820 No need, works fine after the modification.

[@Denis7947.]

@@BuyitFixit oh ok

[@jonasschinkler5376]

Never thought that one could fix a design fault like that, good to know!

[@BuyitFixit]

Thanks 🙂👍

[@TechGorilla1987]

I very much admire packaging engineering and design. Back in the 90's, I used to hang around a couple of people that were attending Penn State for packaging engineering degrees. Some of the projects that they had to do for class were very interesting. Like being given an object and one sheet of material to create a box to encompass the thing. It's always fascinated me.

[@BuyitFixit]

Yes, unusual shape box, but two if them fit together nicely as shown in the stack on the video thumbnail 👍

[@davebrooks993]

Thank you for taking the time to identify the ic’s. Really appreciated.

[@BuyitFixit]

No problem 👍I usually try and do this on most devices I look at. I've been there myself where a chip has blown on something and I've been trying to find pictures or videos of the board to try and identify it.

[@andreim841]

I love your calm and collected approach when repairing something. Like AvE said...if it's efft is not like you can eff it even more :)

[@BuyitFixit]

Thanks 👍 and exactly right 😂😂

[@generaldisarray]

Excellent fix. It just goes to show you that even Philips makes mistakes. They were once a top electronics producer with great quality and reliability. However, like many others, their quality has now become inconsistent.

[@BuyitFixit]

Thanks 👍🙂

[@argusdenia]

Philips doesn't exist as an electronics manufacturer. They only licence the name.

[@generaldisarray]

@@argusdenia well the Philips brand used to be good, now it's just hit and miss whether the product is any good or not

[@samuelfellows6923]

😠 ~ I think “PHILIPS” is now a zombie brand and being used by “Chineseum crap” factory’s - a name slapped on their polished turds

[@dyslectische]

China shit with a philips name. I'm dutch and just to tell sorry about it.

[@zedcarr6128]

Amplifier Classes: Class A - Amplifies the whole wave cycle, it needs a lot of bias to do this and is conducting all the time. Great sound quality, but around 25% efficient, 75% dissipated as heat. Class B - Amplifies half of the wave. Not used singly in audio amplifiers, but used in RF amplifiers. Efficiency in the 70%+ region. Class AB - Probably the most common audio amplifier configuration. It has the efficiency of a class B, but two active devices are used, one for the positive cycle, and one for the negative, so both halves of the wave cycle are amplified like in a class A. They have to be biased to reduce crossover distortion to a minimum, this happens when one device switches off and the other switches on. Class C - Amplifies less than half of the wave cycle. Not used in audio amplifiers, but is used in RF amplifiers. Technically 100% efficient because there is no bias and the device is off when inactive and not passing a signal, in practice they are about the same efficiency as a class B. Produces a lot of distortion, but this is filtered out by the tuned filters of the RF output stage of the transmitter. Class D - Uses PWM (Pulse Width Modulation) where the active devices are either fully on or fully off, i.e. the device is switching. In this configuration, the active devices only dissipate power during the transitions from on to off and vice versa like digital circuits do, which increases efficiency. Efficiencies of over 90% are common with class D amplifiers, and amplifiers of hundreds of Watts can be squeezed into small enclosures that you can pick up with one hand. The downside is that they are more complex, but their power to weight and size factor negates this.

[@BuyitFixit]

Thanks for that 👍

[@MichaelBeeny]

Class D are very efficient at the rated power but at low powers surprisingly inefficient. Most of the inefficiency being lost in the output filters as heat, as they still need to remove the switching frequency, even with no output.

[@welshdave5263]

I love seeing the fault fining process and learning new methods, this a well earned SUB, cheers!

[@BuyitFixit]

Thanks for the sub!

[@lifeisfuneh]

Your persistence always gives me so much encouragement to try again when I'm stuck troubleshooting ! THANK YOU!

[@BuyitFixit]

You're very welcome, and thanks so much for your kind comments 👍

[@Mymatevince]

Amazing skills Mick, great video!

[@BuyitFixit]

Thanks Vince 👍yes a little bit out of the norm this one 🙂

[@mattc3385]

A beautiful mind. I have no other words. Just so impressive. Well done!

[@BuyitFixit]

Thank you kindly Matt 😊👍

[@kentb3175]

Subbed, excellent detective work. It seems that Phillips knew about the problem but rather that go through the expense of recalling and reworking them back from the retail supply chain told them to send them off to e-waste. Seems bonkers from a sustainability point of view.

[@BuyitFixit]

Thanks 👍I've had things like this happen before with the FLIR thermal camera I repaired and they were unwilling to help, or the solar inverter I repaired, then needed a service password to change a setting in it. I emailed the company for a password and they said pretty much it's an old model, buy a new one. Ended up having to reverse engineer their software and make my own password tool. I did videos on all of these with the emails that I sent them. I emailed them back telling them I fixed it myself and here's the passwords that I made myself 😂😂😂

[@RealBLAlley]

Everything is disposable, which drives me nuts. Having to discard an entire product due to one component failing is shameful. worse, many manufacturers deliberately sabotage products by making key components out of the wrong material and that is always the part you can't buy. They also add unnecessary components that are designed to fail at the end of the "warranty" period. In my opinion it should be a law that manufacturers provide a lifetime warranty against any defects with no cost to the consumer, instead of being allowed to charge "processing" fees that actually cover their expense to replace the product. If we had such a law, products would be much better quality.

[@BuyitFixit]

Or even worse, actually repairing a product, then needing to adjust something but they refuse to give you a password or code (such as the solar inverter video I did) where I ended up having to take matters into my own hands 😂😂😂😂

[@pauljs75]

@@RealBLAlley Better yet, the manufacturer should be responsible for e-waste that is sent right back to them at reduced or no cost to the buyer. Make the deadline something like 10 years. They'd fix their act rather fast if it became their problem.

[@mjouwbuis]

Philips hasn't had facilities to do rework on consumer audio since at least the Gibson Innovations bankrupcy, but realistically probably also before they sold off to Gibson since most of the products were already outsourced and their own facilities brought down to a few hundred employees. They might have gotten some financial compensation from their supplier and that's it.

[@mikecass8306]

Great forensic work as usual, thanks Mick 😀

[@BuyitFixit]

Thanks Mike 👍

[@davesmith8101]

Brilliant detective work,very impressed with it -and the outcome. Well done, subbed.

[@BuyitFixit]

Much appreciated!

[@en2oh]

The long time subscriber hit this one out of the park! I don't know what they're worth, but looks like a fairly simple modification will make them usable again! Great problem solving skills!

[@BuyitFixit]

Thanks 🙂👍yes a little bit from the normal this one 🙂

[@torvador9384]

anything to keep em out of landfill!

[@davidhollfelder9940]

Class C amplifiers are for RF transmitters. They run in cutoff at idle, and produce positive “peaks” (when RF drive signal is present) intended for resonant filters and antenna.

[@BuyitFixit]

Someone mentioned that in another comment but thanks for taking the time to also comment and let me know 👍

[@theoldbigmoose]

Great job mate. I enjoy your videos and learn from each

[@BuyitFixit]

Awesome, thank you!

[@Dime_Bar]

Excellent work again.

[@BuyitFixit]

Thank you! Cheers!

[@LouistTheBravest]

I have to say, I did enjoy watching the issue identification process and also the applying of a fix. I'm a software developer and most of my work consist of analyzing strange happenings, go throught the rabbit hole, and eventually propose or apply a fix that could solve the problem. You video shows why knowledge and experience, but also information retrieval is so important. Never assume the others did everything right, and trust your feelings. Sometimes thing are just not right, no matter how pretty or elegant they look like. At this point just a quick shout-out to the internet, that made my live much much easier, having many active communities worldwide to use for information search. I'm sure you feel the same.

[@BuyitFixit]

Thanks👍 I used to do a bit software too :) ...and reverse engineering. I did some of that with a solar inverter as after I repaired it I needed to adjust a setting so needed a code to access the service menu and the company were not helpful at all! So debugger...etc. I did a video on that too "No password No problem" and ended up writing my own tool to generate passwords to help others in the same situation 🙂 Also I did some messing with the Medical Ultrasound scanner (video too) where I unlocked a ton of hidden features...

[@ob1skywalker82]

Nice fix ! thanks for sharing👍

[@BuyitFixit]

Thanks 👍and thanks for letting me know 🙂

[@Turb0esky]

Great video. Highly educational. Learnt a heap from you. Thanks from. Australia.

[@BuyitFixit]

Thanks 👍 Glad you liked it. Hopefully you'll like some of my other videos too 🙂

[@Turb0esky]

I have been loving them! Appreciate the time you take to explain the circuits. A lot of repair vids seem to go straight to the fault or diagnose mostly of camera. It's great to see you work it out methodically even if it might be slower to repair.

[@skjerk]

Very interesting video - learnt a lot!

[@BuyitFixit]

Glad you enjoyed it!🙂👍

[@chrissmith7655]

Hi, sound man, sound! Well done as usual. Many thanks, great the way you explain every step. From Nr Chester.

[@BuyitFixit]

😂😂😂Thanks 🙂👍

[@kedjyrooney1225]

Genius, great work.

[@BuyitFixit]

Thank you very much👍

[@KallePihlajasaari]

Great video. Thank you for taking the time to record the process. There is one very nice thing about date formats that are YYYY-MM-DD They sort properly in any system as the most significant numbers are to the left like in text. There are also no formats starting with the year that have the day in the middle. I always store dates in text files in this format because they will always be imported correctly by a spreadsheet application without day month ambiguity.

[@BuyitFixit]

Thanks 👍and thanks for the date format info 🙂

[@JamesSmith-qs4hx]

🎉20K🎉 well deserved.

[@BuyitFixit]

Thanks 👍

[@MR.T..]

great fix....i bet the bloke who has the job lot / container load has now set up a repair production line to fix the lot ..following ur youtube video....

[@BuyitFixit]

I just messaged him earlier, and he's done one so far but not tested it yet 😂😂😂

[@wherami]

The fixer of Everything!

[@BuyitFixit]

Well...I do try 🙂👍

[@wisher21uk]

Brilliant Mick I knew you would get the problem sorted out, there no end to your talents 😊 P.s haven’t forgotten be in the post in the next day or so thanks Mick 😊

[@BuyitFixit]

Thanks Gary 👍

[@wisher21uk]

@@BuyitFixit no thank you ☺️

[@videomentaryproductionschannel]

Nice Job Good bit of detective work, Im amazed they dont put at least a small heat sink on that amp chip great video

[@BuyitFixit]

Thanks 👍

[@mistermikeanson]

Nicely done!!

[@BuyitFixit]

Thanks 👍

[@LeeLeesAdventures]

Great faul diagnosis you need to now give them the fix and take a commission on what they sell lol you the man. 👍

[@BuyitFixit]

Thanks 👍😂😂😂

[@BoatzUK]

Great stuff as always 😎

[@BuyitFixit]

Thanks mate 👍

[@Popeyes66]

I always knew you were a sound guy Mick.

[@BuyitFixit]

😂😂😂😂😂😂👍

[@ToumalRakesh]

Can we talk about that irregular box shape? What a nightmare for shipping!

[@BuyitFixit]

I think they tessalate like on the thumbnail picture, just like Tetris 😂😂😂😂

[@jamiejoker118]

Well done great stuff

[@BuyitFixit]

Thanks 👍

[@stefanopassiglia]

Amazing. Thank you!

[@BuyitFixit]

👍🙂

[@NicksStuff]

That was very impressive

[@BuyitFixit]

Thanks 👍🙂

[@rupertprice5508]

I would love to have seen the result using low resistance inductors . Ie: also higher quality inductors. Higher saturation current. loved the video. thanks for all the effort.

[@BuyitFixit]

Thanks 👍

[@cheapasstech]

I have the service manual for these - drop me a line if you want it ! According to schematics those burnt ones should be 10ohm

[@BuyitFixit]

Thanks for that! Yes10 ohm, the guy sent me a picture of the next model up with the HDMI socket and you can see the resistors on that. Strangely enough that model doesn't overheat but they changed the design of the output filter it seems.

[@cheapasstech]

I don’t know if you’re on Phil’s discord ? Same handle as here !

[@tomharris1457]

Nice bit of deduction! One thing good about the 'net, looking up data sheets!

[@BuyitFixit]

Thanks Tom, yes the internet is usually good for things like that 👍

[@jonnyduncan7056]

Amazing fault finding skills, what do you do for your 'day job'? A man of many talents..

[@BuyitFixit]

Thanks Jonny. I'm kind of semi retired. Although we run a small farm with around 70 sheep, and I also do KZbin a bit although both are more like a hobby than a job.

[@stevew9945]

Good, job interesting video

[@BuyitFixit]

Thank you very much👍

[@liveuk]

Nice to show how we all like to learn from doing.

[@BuyitFixit]

Thanks 👍

[@giantkeytec]

hi,i`m giantkey,your video amazing,and it helps me to gain more knowledge to fix an item.

[@BuyitFixit]

Thanks 👍glad it helped 🙂

[@stephenlittle7534]

Well done for finding they messed up in thier design 😮😮. And with your mod made it nearer to what it should have been. I would buy a modified one off from you.

[@BuyitFixit]

Thanks 👍Honestly I wouldn't bother (not that I have any to sell) but they not very good. I'd save your money and buy something decent.

[@stephenlittle7534]

@@BuyitFixit Thank you for being truthful.

[@BuyitFixit]

No worries 👍

[@TechOne7671]

Brilliant. Thanks

[@BuyitFixit]

You're welcome!

[@darrenwardell3079]

Looks like you could be onto making a few bob fixing that container load.👍 Good on ya😊

[@BuyitFixit]

They're not mine mate. I was just fixing this one to show the guy how to do it 🙂

[@andymouse]

How you do all of this thinking and research in 40 minutes I will never know ! so have you 24 more to fix now ? or half a cargo ship !! great stuff .....cheers.

[@BuyitFixit]

Thanks Andymouse 👍. Unfortunately a lot longer than 40 mins... I actually did a lot more research than is on the video including downloading a tool from Texas Instruments to work out the values for the filters, but I didn't want to make the video an hour long. Then the time to edit it, as I had 5 different camera sources on this video. (An iPhone for the start and finish (as I didn't want to unmount my overhead camera), the thermal camera, microscope camera, camera on the scope and the usual overhead camer). It took me a good couple of days to edit and watch back, re-edit etc. The guy who has the other 24 just wanted to know how to fix them. I think he's already done 1 as we chatted over whatsapp 🙂👍

[@andymouse]

Yeah I can believe it ! thanks once again for your monumental efforts...cheers. @@BuyitFixit

[@walterjwalnut9964]

You wondered what a class C amplifier was. Class A amps the active element conducts all of the time, Class B uses a pair of active elements with each element conducting on either the positive or negative half cycle of the waveform (lots of distortion around the point where elements turn on due to non linearity), Class AB is similar to Class B except that both elements are biased to have a small current flowing when then they would otherwise be non conducting in a Class B system (better compromise between distortion and power efficiency. Class C amplifiers have the active elements conducting for much less than half of the output cycle, higher efficiency, considerable distortion of the waveform. The were primarily used for RF circuits where there is very significant narrow band tuned circuit filters to eliminate the distortion. However the narrow band tuned circuits severely limit frequency response etc, hence the limitation to RF circuits rather than audio circuits. These 4 classes of amp have existed since the vacuum tube triode was invented and are applicable to any active element family (vacuum tube, bipolar transistor or FET). Class D really only became viable as a design option when FET and particularly MOSFETs become commonly available as bipolar transistors generally either lacked the current capability but had the speed, or had the current capability but significant turn on/turn off delays.

[@BuyitFixit]

Thank you for taking the time with your detailed explanation 👍

[@maebeans]

you picked that "subwoofer" up way to easily, this seems like a very good quality product /sarcasm

[@BuyitFixit]

😂😂😂Check out the "Fantastic" reviews it gets on amazon 😂

[@TheRealBobHickman]

Your diagnostic skills are sound

[@BuyitFixit]

😂😂😂Thanks 👍

[@Rias-Gremory-a-gamer]

Sorry for my reaction i am a fan of this channel and still new to it. I know its not you but that board looks like they have used very cheep nasty ass components as well.

[@BuyitFixit]

Yes, it does look cheaply made 👍

[@DCPHONEGUY]

I love watching your channel, you are so knowledgeable and logical in your approach to your repairs, my only comments are: when you put text up on screen I have trouble finishing reading it, could you leave it up a little longer?, my second thing is: you find and fix all of these things, why haven't you found a nice de-soldering station? I have a Pace micro portable which I love but there are some much less expensive ones that I think would really help you in your work. Keep going with the wonderful videos , I sure do enjoy watching you tackle all of these items, you get right into the component level which is so helpful. Oh yes, and I forgot, maybe a nice cordless screwdriver (does Milwaukee make one that you can repair?).

[@BuyitFixit]

Thanks 👍I've been on the lookout for a decent rework station. The soldering iron I'm using is ok (although I may get some better tips). The rework station is just a cheap 858D which is not really up to the job on some things. I'm not a fan of cordless drivers, I've used them before and find it hard not to strip screws especially in plastic. I always like to give them a turn manually the opposite way until they click before screwing them in so they don't cut more threads in the plastic. Thanks for commenting 🙂👍

[@DCPHONEGUY]

A cordless screwdriver with a good clutch mechanism, not one that is really a drill.

[@robertbruce7686]

Even the cat dislikes the "lift musicke" 😆. Excellent video!

[@BuyitFixit]

😂😂😂Thanks 👍

[@andytipping70]

your guy must be some kind of magician - changing the Ic without disturbing the silicon around it - just saying

[@BuyitFixit]

It was a different sound bar he tried changing the IC on but it didn't make any difference. He sent me a fresh one that hadn't been messed about with 😉

[@styzr]

Brilliant!

[@BuyitFixit]

Thanks 👍

[@Bigbluevwvan]

That thermal camera is very useful i think i need one lol

[@BuyitFixit]

Yes they are very handy! I put some links in the description of the tools that I use and also did a video review on that camera VS the FLIR thermal camera that I repaired in a previous video.

[@peterlarkin762]

Class D amps are amazing, but fundamentally flawed for musical reproduction. 1. It's turning an analog AC audio signal into pulsed emissions with lots of high frequency noise. So it has to be filtered before turned into physical movement at the speaker. Traditional amps do have networks before the speaker but it's more about protecting the amp from inductive loads etc and not really filtering anything in ideal circumstances. They are functionally better. Class D is used for efficiency, size and can be made VERY cheaply. There are some really good D class hifi amps but are complex custom designs that aren't cheap. Class B amps can be made with practically no crossover distortion and can sound amazing, Class A can heat up your house but sound crap if the circuit is poorly designed. Tubes can sound like solid state, and vice versa. My point is, it's the overall amp design and not a 'class' that dictates sound quality. I have designed super simple 25W class B amp with 2 Darlington's and an opamp per channel just for fun, and now use that way more than my very fancy lateral MOSFET monster amplifier.

[@BuyitFixit]

Interesting, Thanks for your input Peter 👍

[@chgabbel]

I didn't buy any Philips labeled stuff since over 20 years by now. The reason for it is that I remarked how much of their stuff does just survive the warranty.

[@davidgutting4317]

I saw someone use an E-cigarette and fill it with rosin to create a white coating on the circuit bord and them powered up the bord to find the hot componnents that wet out the rosin vapor film. Neat trick when you don’t have a thermal camera.

[@BuyitFixit]

Yes I bought one of those a while back too, although I've not used it yet. At a push you can also use IPA and see where it evaporates first when power is applied 👍

[@davidgutting4317]

@@BuyitFixit nice trick, I’ll try it. I really like your videos there aren’t a lot of electronic diagnostic videos out there and you have a really simple methodology for fixing the problem.

[@BuyitFixit]

Thanks 👍Much appreciated 🙂

[@marcyd2007]

Well done Sherlock, another awesome bit of detective work. I guess we need to look out for a flurry of Phillips Soundbars hitting eBay over Christmas now he knows how to fix them 😉

[@BuyitFixit]

Thanks Marc, I think he bought these a while ago, but he got stuck on diagnosing the problem.

[@KRich408]

It's everything I have several BlackVue dash cams I find 2-5 have issues that require replacement. QC is probably the majority of the issue with modern electronics. That build them so fast.

[@BuyitFixit]

Could well be. Thanks for commenting 👍

[@evkessel020675]

Haha, you're not an expert you say in the description. I know many "experts" with much less skills. Great approach to get to a possible root cause. And great to experience you can think out of the box (a design fault is not a common path to follow)

[@BuyitFixit]

Thanks 👍🙂

[@user-zo1kn8ob7h]

2:20 bro my dearest blessings how long were you having to blast this full vol omg

[@BuyitFixit]

😂😂😂😂😂👍

[@dennispowell7719]

You should build your own products mate atleast people could rely on its good quality build and performance if was designed by you as someone who loves fixing faulty electronics myself i really enjoy your content keep the videos coming mate amazing work and logic 👍

[@BuyitFixit]

Thanks 👍I'm no expert. I haven't really designed much apart from an internet connected incubator for hens eggs a while back, and a couple of arduino button bashing games and a shooting gallery type game.

[@Lightrunner.]

Hey , good Video 👍👍👍👍👍🍻 The heatspot isnt a faulty design from the Ingenieurs. Smaler components which a little bit heat radiate are a sign of power🤣🤪🤪 Circuits that work at border area are cost effective and guarantee a faster failure after warranty. No mistake, a good obeselezens calculation.

[@BuyitFixit]

Thanks 👍😂😂😂

[@mjouwbuis]

7:00 first impression: brown conducting glue can also contribute to problems like this.

[@BuyitFixit]

Yes, I had that on the JVC valve HiFi I looked at a few videos back. I'd not came across this problem until then 👍

[@pqrstzxerty1296]

Philips hasn't made any consumer stuff since 1999, as its sub contracted out under brand franchising. 2022 Philips completely sold its consumer compaines. Philips only does a military and medical client base now. I suspect its a class N amp (digital ic amp), and using a trick to decrease audio bandwidth to achieve a louder audio output. Other trick I seen them use 2ohm or even 1ohm deep throw speakers, on a 8 ohm nominal outputing amp, and they just use these hybrid crossover filters for control. Creative Lab has a simular problem with the 1st and 2nd revision main pcbs on the flagship Gigaworks T40 series 1 and series 2. Just like SMPSU's, the boards with N class (one chip simple design digital amps) ic amps tend to blow throu, as the fault stress of one going faulty component stresses out multiple compoments making them a different value, making the system to snowball sprial to another fault shortly after some time of a working fix. The T40 pcb are unfixable, thus why so many 2ndhand T40 's on sale on ebay. In my opinion its these cheap psu plugs and smpsu chocoboxes that allow mains spikes throu, and so on the limit for wattage to save money that the psu output regulation wobbles and usually to a higher value for a moment taking or weakening these all in one amp ics. These pcb designs also drives these amp ics hard, to get the maximum audio loudness out. So these ics are run hot with no heatsink and in a non vented enclosed box. They are simply made to cheap.

[@BuyitFixit]

Yes, cheap and not very good judging by the Amazon reviews..

[@TexasVeteranPatriot]

Yep, all the AV ops were sold to Funai in 2013..

[@cheapasstech]

That brown glue becomes conductive in each and every device … some tannoy speakers get killed because of that

[@BuyitFixit]

Yes, came across it a few weeks back on the JVC HiFi I looked at. I don't think it was the cause of this failure though, as all of these devices were pretty much brand new.

[@MoseyingFan]

Also known as the brown snot of death. It's tan color when fresh, but turns brown when it soaks up moisture. I repaired a LCD display where the snot corroded away the coating of some resistors on the power board.

[@cheapasstech]

@@MoseyingFantannoy 6d - even eats away at the traces

[@SuperBoobaloo]

Bravo. Think how many devices you have saved from the recycling.

[@BuyitFixit]

Thanks 👍That was partly the idea for the channel. I've always disliked things going to recycling when mostly it's a tiny component and I've even seen perfectly good working stuff ending up there too 🤦‍♂️

[@garystevens6831]

Are you at MyMateVince's house? you've got his carpet! 🤣

[@BuyitFixit]

😂😂😂😂 No lol. I've not noticed that, you've sparked my curiosity now 👍

[@gwf82]

I had an issue with a Vizio sound bar I got on clearance years ago and it worked great until it didn't, I would turn on my TV which would turn on my soundbar and it didn't turn on as usual. So I hit the power buttons on the remote and on the bar itself and still no life, I tried power cycling it and it still didn't work. I figured it was dead, so I left it unplugged for about a day and then it worked. I began to suspect that the built in power supply was faulty and was going to change it but Vizio doesn't make parts available for that model so while it still worked I got the power output of that power supply (12v) and just removed that junk and put an external 12v, 5 amp power supply and it worked great for years after that until I upgraded to a newer Vizio soundbar.

[@BuyitFixit]

Nice workaround 👍I did something similar to a radio someone brought into the repair cafe where I volunteer at. The internal transformer had failed that produced the 9V DC it used. I just found an old external 9V DC adapter and wired that to the board inside 🙂

[@pauldavies6037]

Great job Class D amplifiers are high frequency switching devices and must have very good sharp filters on their output to reject the switching frequency I'm afraid like a lot of stuff these days poor quality control and design errors yet they get past QC and are for sale

[@BuyitFixit]

Thanks Paul 👍

[@pauldavies6037]

@@BuyitFixitgreat job pal

[@felixokeefe]

Well technically as the switching frequency should be far above any audio frequency you could run a class D amplifier without an output filter. Only then the switching frequency noise would be dissipated as heat in the voice coil of the loudspeaker instead of in the filter. That and speaker wire becomes an antenna radiating the switching frequency as rf noise.

[@ralphj4012]

Good analyses. Looks to be a Friday night design. The electrolytic at 12:54 is above a ceramic cap and an-off-the-top-of-my-head calc shows 1.5A into the speakers at 20W through what looks to be 1A capable inductors. Oops. Your gonna need a bigger mat.

[@markturner7459]

The data sheet showed 8ohm speakers..how would them using 4ohm speakers effect things?

[@ralphj4012]

@@markturner7459 My approx calcs were for 4 Ohm, with 8 Ohm you halve the current (sort of). But, just shoving in a hybrid filter to then trim the top end increases the current (more damping) and that's probably why the resistors burnt. The datasheet looks odd, it seems to show the same filter components irrespective of impedance. I would be very surprised if Philips designed that (unless a few pints of Jenever were involved).

[@BuyitFixit]

The recommended filter page on the datasheet showed the same values for 8 ohm and 4 ohm speakers 🤷‍♂️

[@pedroveloso9707]

by the first look it likes part off the crossover to speakers

[@ralphj4012]

@@BuyitFixit Indeed, though the impedance will make a marginal difference, the cutoff seems to have been changed from 44kHz (the 33kHz in the datasheet is wrong, that would be true for only one inductor) to 36KHz (if the ones on the PCB are 10uH), closer to what the datasheet was aiming for. Pure guesswork on my part but I suspect they intended 8 Ohm speakers then fitted 4 Ohm without compensating for the increased current, frequency response etc. Your workaround should be ok, but if your subscriber has all the time in the world then consider doubling the power handling capability of all the components in the output circuits, as well as investigating that 'flying electrolytic'.

[@letrainavapeur]

I remember fixing several Phillips portable radios in the '70's, the volume control was mounted on the edge of the circuit board and the corner of the board and control used to snap off. Awful design even in them days.

[@BuyitFixit]

Interesting, Thanks for commenting 👍

[@derekpaisley620]

Just started watching, good content interesting. Can i ask you put a link to your phone usb camera , yiu used for the heat detection. Is it android? Regards

[@BuyitFixit]

Thanks, yes it's android. There's a link in the video description. They do an iphone version too.

[@davidgilpin5200]

I expect the subscriber is going to want you to do this modification on his other soundbars so he can sell them on... Great work, and nice explanation of audio amplifier design. Class D amps are everywhere these days - it is how all smartphones can produce so much audio in a small form factor, efficiently.

[@BuyitFixit]

Thanks 👍 He's quite capable of doing it himself as he repairs bluetooth speaker. This one he was just having trouble working out what the cause of the problem was 🙂👍

[@RaduTek]

"it is how all smartphones can produce so much audio in a small form factor, efficiently" Have to give credit to Digital Signal Processing too. Without a DSP, phones, TVs and even sound bars would sound much worse. The DSP lets manufacturers improve the sound of a speaker that's either constrained by space, size or price.

[@pauljs75]

Makes you wonder if they're skipping out on proper QC testing somewhere with these things if enough get made with the same problem? Also you'd think for environmental testing they'd consider some people like the heat on rather than having the AC set to ice-box room temperatures, and they should use both ends of the range while also pushing the device to its limits. If not that, then somewhere in the pipeline people are signing off on defective stuff because of things like production delays. Wouldn't be too surprised if that happens too.

[@BuyitFixit]

Could well be the case. Thanks for commenting 👍

[@manickbarry]

Nice work hope your friend gives you a nice commission for your wizardry

[@BuyitFixit]

Thanks Barry 👍

[@gd2329j]

The problems show up after a design is changed in production or by the purchasing department ! Also when outsourcing manufacturing the assembler could changed the design . Low cost high volume items with multiple suppliers will suffer most . It shouldn't happen but it does & with every order you're just flipping a coin “goldmines or landmines” ! Normally it's all about someone reducing costs & just clearing the warranty .…....... You're also probably just moving boxed product so it's hard spotting problems .

[@BuyitFixit]

Thanks for your insight 👍

[@Manu-nr1yt]

I wonder why they even attempted to create their own filter. It usually is no bad idea to stay close to what the chip manufacturer suggests.

[@BuyitFixit]

Yes agree 👍 perhaps they were trying to get more power? Or improve the audio quality?

[@d614gakadoug9]

My guess is that they were either finding problems with EMI/RFI interfering with the wireless stuff in the box or they were failing to meet CE or FCC or other standards for emissions.

[@d614gakadoug9]

There is something strange afoot there. The over-temperature shutdown threshold for the amplifier IC is nominally 150 °C (die temperature). The top of the package will be cooler than the die, but not by a huge amount. I'd expect the top of the package to be in the range of 100 °C at shutdown. Since no testing to shutdown was done with board exposed we have no useful data. My suspicion is that shutdown was occurring due to something in the filter network causing short circuiting when hot, which also causes shutdown.

[@windward2818]

In repairing consumer audio do you use an isolated AC power supply to power the mains?

[@BuyitFixit]

No, I don't have an isolation transformer. I only do this as a hobby, and don't specifically work on audio, it can be anything from a Thermal camera that I've repaired to finding a fault on a tractor 😂

[@mohindersembi7647]

Wow very nice video you are professional engineer master of the master 👏 I have philips pronto tsu9600 touch screen remote control can you please kindly do a video of it as its not working ie not powering up it was working before I changed new 18650 battery full changed still it doesn't switching on? If make a video of this it will be the best video on KZbin please kindly help me on this issue 🙏 waiting for your reply Thankyou ps how can I send this to you for repair 🙏please

[@BuyitFixit]

Thanks. There's an email address on the channel "about" page under "for business enquiries"

[@kapilsds7]

Over miniaturization and over power efficiency is killing electronics lifespan.

[@BuyitFixit]

Yep, 'they don't make them like they used to'

[@user-cd4wn1of9q]

Comprehensive low-end sound quality factors: SMPS power supply & D class amplifier & small diameter speaker & Bluetooth

[@KRich408]

I wonder if Phillips and Polk sound bars are made in the same facility? I have a Polk with Alexa that came in the exact same box. The remote even looks the same.

[@BuyitFixit]

Could well be. Sounds like it from your description 👍

[@d614gakadoug9]

An article from _EE Times_ titled _Understanding output filters for Class-D amplifiers_ by John Widder and Yun Tao Zhao, 2008, might be of interest to those who don't choke on a bit of quite simple math.

[@TheBoringReason]

i was like.. "weird hes working on that but it was not it that spot... oh well atleast he fixed it" then i reconsidered the size. that thing aint big xD

[@BuyitFixit]

Just a bit awkward to fit on my desk 🙂

[@xcoder1122]

Calling a PWM amp a digital amp is not totally wrong. In the end, it just flips a switch very quickly and this switch only knows two states: On an off. And that's in fact a digital behavior. The analog wave forms are not generated by the amplifier itself but by the LC resonator (capacitor and inductor) following it and how the wave form looks like is controlled by varying the switching times of that digital switch. And the switching time is controlled by the analog input signal. This is BTW exactly how a 1-bit DAC (digital to analog converter) works, which is the most common form of DAC in use today. People think that DACs must be 16, 20 or 24 bits, as their audio recordings are in that format but instead of fabricating a 16 bit DAC that can produce 65536 different output levels, it's much easier to produce a DAC that only knows 2 output levels and then convert the x-bit value into a switch time that controls how long this 1-bit DAC will remain in one state before switching to the other one. The result at the final output will look the same either way when done correctly. There may be a tiny ripple with a 1-bit DAC but it's at such a high frequency, way higher than what a speaker can produce (so it would never transform into an actual audio signal) and also easy to filter out using an active or even passive low-pass filter, that cuts off after 20 kHz.

[@BuyitFixit]

Thanks 👍yes was thinking that but when I looked on the internet it said it wasn't digital as that's what I was calling it at first 🤷‍♂️

[@Agent24Electronics]

The inductor measurement probably seemed off due to the limitations of your tester. I'm guessing that it only goes down to 0.01mH otherwise it should have autoranged to µH at that point (I'm guessing it can't measure that low). And it probably isn't calibrated well enough so what should have shown as 0.01mH showed as 0.02mH. Does the tester have a specification sheet of its range capability?

[@BuyitFixit]

Yes I was thinking the same, it's only a cheap tester which is why I assumed the inductors were probably ok, but it's the only tool I have that measures inductors currently.

[@demofilm]

I have seen issues with sound bars having capacitors right above the heat sinks... No idea who comes up with that

[@KirrSuitor]

Музыку чем-то группу Чиж напоминает...

[@RealBLAlley]

Someone had a container full of a single product all with the same fault. That's not janky at all. They already replaced it with the B5306 which works well. It's a shame they didn't simply update the board and replace the faulty ones instead of designing and manufacturing an entirely new model while these were packed up as e-waste.

[@BuyitFixit]

Well hopefully they learn from their mistakes...

[@TechGorilla1987]

"0" ohm resistor - R69. Nice.

[@fluffyblue4006]

Philips is not making this kind of equipment anymore. They just sell their name for use on products by others. If Philips themselves would have made this product back in the day, it would have more drivers in it, including a pair of tweeters. And proper inductors. I have never seen these black plastic things used as output inductors in a class D amp. Usually, you'll see those SMD ferrite cubes in small amps, or 'naked' coils wound on a round ferrite core in bigger ones. I think those black plastic conductors are fine if you run a class D amp on 5Volts or a Li-ion cell. Not good for applications where a certain amount of power is involved.

[@BuyitFixit]

Thanks for that. Yes I think a few companies like wharfdale I think it was who used to also make good stuff back in the day now just license their name to other manufacturers.

[@d614gakadoug9]

The inductors probably would run cooler with the insulating sleeves removed. It's hard to say exactly what core material might have been used. I suspect it is just ferrite. With the open magnetic path of simple solenoid-wound "spool core" inductors ferrite is OK. If you are referring to toroidal inductors by "round ferrite core" they will most certainly not be ferrite. The core material will most likely be a powered iron. There are many formulations of powdered iron in use. There are more "exotic" materials with better properties, but they range from somewhat more expensive to vastly more expensive.

[@10100rsn]

The values of the inductor and capacitors in the filter on the datasheet are different then what you measure on the board because the datasheet schematic is using an 8 ohm speaker and the speaker bar is using 4 ohm speakers. The excessive heat might be due to the inductors and resistors in the filter circuit being under sized. As the inductors heat up their current carrying capacity drops, their inductance value changes and being in a small enclosed space probably forces a thermal runaway that eventually damages the inductors and resistors.

[@10100rsn]

Also, in the datasheet there is a ground in the filter design but there doesn't have to be. The filter can be designed just between the two outputs of the H-bridge. Edit: But you need to use higher voltage caps and higher watt resistors as the caps are seeing a higher AC voltage. The filters are difficult to get right and those original capacitors in the original configuration probably didn't have a high enough AC voltage rating to be in that particular filter, they looked really undersized for that even at ~20-40w because of the switching frequency of the amp.

[@BuyitFixit]

Interesting. On the datasheet it shows the 4 ohm filter just under the 8 ohm one. However both show the same value. I did download a tool from TI to work out the LC filter and it said that a 1.2uF would be better. A 1uF gave a slighty higher cut off frequency. The calculations for all of it were way over my head 😂 luckily they had that spreadsheet that worked it all out for you.

[@10100rsn]

@@BuyitFixit Yeah, I got that spreadsheet too. Class D LC Filter design tool. The "differential mode" design is usually used for BTL/PBTL modes because it can be cheaper with fewer components but it can be dangerous if you don't choose the right components. The capacitor in the middle can look like a dead short at higher frequencies. The "hybrid mode" is pointless to me as it is just as dangerous as the "differential mode" version and doesn't give much more benefits. With the "common mode" filter design is best as the capacitors are not stressed as much and don't need 2 to 3 times the AC voltage rating of the output.

[@d614gakadoug9]

An inductor running at 50 °C is perfectly OK unless the core material is something very strange with an exceptionally low Curie temperature. Any change in inductance due to temperature would be of no consequence in a circuit like this.

[@10100rsn]

@@d614gakadoug9 Yes, the main thing is the AC rating of the capacitors at the output frequency of the class D amp. The filter needs to filter out the PWM frequency and using cheaper capacitors with a series resistor does not help the capacitor handle the AC voltage or frequency of the circuit. Might help with DC voltage but not really AC voltage. The capacitor can still look like a short circuit at the higher frequencies so its a bad idea. The next problem is the current capacity of the inductors but really only when the capacitors are underrated. I've had to replace inductors before because underrated capacitors caused excessive current and heating in the inductors. There was a Corsair 2.1 speaker set that was bi-amped stereo + a subwoofer, three chips total. Two chips in BTL stereo mode and one in PBTL for subwoofer. Hi+Mid amp for left and another Hi+Mid amp for left. It was notorious for power supply failures but the main cause was the design of the Class-D output filters (aside from other issues with the heatsink). They chose to use underrated caps in the output and put resistors inline thinking it would help. The burning of the adhesive they threw around the output filters showed that it was literally burning itself to death at regular output levels. The filter components should never be getting that hot. The solution was to redesign the output filters with new caps and also new inductors for the subwoofer section as there was usually at least one bad inductor in the subwoofer section. The subwoofer section was PBTL mode using a hybrid filter that meant a capacitor directly across the + and - outputs and, of course, it was not rated with a high enough AC voltage for that circuit and would explode or meltdown and then kill an inductor or two. The inductors would have been fine had they chosen a capacitor with the correct AC voltage rating for the hybrid mode design. And even TI doesn't have any design notes for us on how to choose a proper rating for those filter capacitors. :/ I forget which exact capacitor I went with for the hybrid filter center cap in the subwoofer section, but I remember the one that didn't heat up or cause the inductors to heat in testing was a film cap rated something like DC 150v while the power supply for the amp was only DC 21-24v output. That is how I discovered the AC voltage rating was related to the amount of heating I observed. Test two different brand caps with the same DC voltage rating but with different AC voltage ratings, the one with the lower AC voltage specs would always heat up more.