My Dad's Internet Radio Boot Loops After Lightning Strike to Router???
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- Опубликовано: 26 янв 2024
- Hi, I fixed this internet radio years ago and it has been in constant use at my dad's ever since. He loves it! Unfortunately the street he lives on had a lightning strike on/nearby and it fried his internet router along with also causing problems in his neighbour's houses. Since then this internet radio packed up. Can it be fixed again? Let's find out.
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Remember that this is just for entertainment and I am not an expert in these repairs. The processes in the video may not be the best way, the correct way or the safest way to fix these things. I do love fault finding and trying to fix broken things, so I hope that comes across in this 'Trying to FIX' series. Many thanks, Vince. 
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For the wifi, I've found that it's faster to change the SSID name and password on the new router to match the old one than it is to set up every separate device
The exactly what ive done in the past and will probably do rhe same when my fibre is fitted next week.
This is true, but some devices usually ios devices and some windows laptops will refuse to connect until you remove the saved network and re connect to it. I don't know if they pickup the MAC address being different or what from the router.
@@tready2008 Absolutely 100% true, it's still faster if you have many devices though.
I have been doing that for years
Also a big fan of changing WiFi names. A Airbnb I stayed in in Norwich had default login for the router so I changed it to 0800norwichsluts. How long it was like that I'll never know 😂
The radio started to behave because it didn't want to spend another night on the cold.
3:30 music layy all your love on me
The 3101Hz tone you can hear is known as a birdie. It is a symptom of the system and normally filtered out so I think you may have some bad capacitors in the amplifier circuit.
I did not know about the naming, but I thought that it's something about the amplifier too. BTW Nice job Vince.
Pre amplifier, before the volume control circuit as you can adjust the volume of the 3khz tone I thought. Use your scope to look at the power supply’s on all the boards. It’s not a ground or mains hum, they are lower frequency noises of 50 or 100hzs, depending on mains rectifier circuit/ earth issues (you don’t have an earth on that device) . I’m not sure your scope in sensitive enough, but turn up the time base setting to find the 3khz tone. I’m sure your esr meter needs new or repaired leads. Shorted leads would give a low (0) ohms. But poor connections, plugs etc would give higher readings.
@@digihorse6730 Also it's probably not from a buck converter as those usually work from 100 kHz to a few MHz. 3.1kHz is too low. Maybe some harmonics? (I am no expert, just guessing)
Thats what I am considering. Hard to troubleshoot but I would say in that area. Could try adding some ferites or blocking caps to quite it down a bit on the power supply and speakers but thats treating a symptom and not the source but it is what I have to do with equipment getting interference from radio transmitters. It's too early and not enough coffee but I do recall something similar being an angry inductor. If I can recall in my notes I will post.
Hi Vince. Those output capacitors are there to smooth the DC, and their values are not critical. It is ok to replace them with a larger value capacitance (if it will fit in the space) As long as they have a high enough working voltage. For example, you could have replaced those 680uF caps with 1000uF, which I think you had in your boxed set.
Thank you Terry👍
@@Mymatevince
Yo Vince
When is part 51 of the Rolls Royce coming out
@@Mymatevince too bad you'll forget it like always and next time again try to match exact value :)
It's OK even other way around. Typical electrolytic caps are ±30% and when used as output smoothing ESR and leakage are way more important compared to actual capacitance. So using, say, 470uF instead of 680uF is also OK most of the time. Output ripple would probably be higher though and longevity till the need of the next raplacement will suffer too. Matching voltage limits is crucial though. Using 16V caps instead of 25V might result in nasty explosion later down the road. Yep RMS measurement for Vdd was 15V in this case but we don't know what actual voltage peaks are coming from the secondary side of the PSU transformer - they might well be around 20-22V+ for some really short durations, one would need to use an oscilloscope to tell for sure.
@@Mymatevincebtw In the Nintendo vid who is Ben
Hi, Vince I have seen this fault when the laser oscillator for the CD player has poor coupling/decoupling capacitors. It could also be from one of the DC buck converters. You could try bridging a capacitor with a good one of known value and seeing the result. I would definitely probe around with an oscilloscope. Love your videos been following you for years. Wow your getting good mate. Pac172
When old electrolytic capacitors get warmer, they tend to fail more with the rise in temperature. An item will often work when cold, at switch on, and then the fault manifests as the internal temperature rises. This used to be a common symptom with old TVs that had a CRT, and changing the old electrolytics was often the cure.
Maybe a dry cap or two absorbed some moisture from the air, maybe even condensation.
A couple of observations, Vince:
1. Never bring equipment in from a cold place and power it on. Condensation forms inside and it will often allow stray currents to flow, which can destroy ICs. Always let it warm up to room temperature. (I realise that this defeats the object of your test but you should be aware of the risk.)
2. In your dad's house I noticed what looked like a tangle of cables on the carpet and maybe a multi-socket strip. If you have plug-top PSUs or chargers plugged into the strip, always place it on a ceramic tile or plate AWAY from anything flammable, such as a carpet, curtain or furniture. That will reduce the risk of fire.
Hi Vince, I had been thinking the noise could be caused by one of the DC-DC switching power supplies on the main board, but they usually run at a higher frequency than 3kHz.
its probably a sub harmonic of the switch-mode oscillator i would be looking for a bad noise suppression cap. the subwoofer wouldnt respond to 3Khz
woofers usually cut off at around 2khz
Nice thought Mick, 😊
The humm/squeel could be due to mains filters. Just a thought. I would put a choke on the cd wires going to the main board. Or even put a chocke on the speakers wires. Nice video, love your channel.
Vince you are much better than most of us repairing things no doubt. I do wonder if the sound was from an DC-DC converter circuit on the main board? Not as high as most switcher carrier frequencies, but was a harmonic of it? The cool thing is that it went away when you put it all back together. Wonder if it was shielding inside that is back around it when installed? Good choice starting with the output caps for the reboot issue! My thought was starting there also for sure. As far as the ESR of that one cap, if the leads would have been shorted it would have shown better not higher. Possibly a loose connection maybe, and then agian maybe cap is bad. Excellent troubleshooting as usual!
I enjoyed it, thanks!
Hey Vince you shuld ask a fellow yt'er Mend it Mark he does audio repairs he may help in your quest in fixing your dads radio
Yeah, just thinking about Mark 😊
Me too😊
Bonjour Vince, vos vidéos sont très instructives et géniales.Merci pour çà! Superbe chaine en tout cas Bravo!
Here's a tip that may save your life.
When working with high voltages always keep one hand in your pocket.
That's because 100V across your hands will stop your heart :(
But if you accidentally touch ,say, 240V with one hand it will run down your body to your feet.
You will get a massive shock but your heart will keep beating.
Or make it even safer, get an insulation transformer and one hand in your pocket and there's no chance of a fatal shock 😲
Could I also add, you may get an electric shock. Electrocuted means you died.
PS, Take off that wedding band. PPS. Pink underwear is the safest !!
That’s as funny as a string of people holding hands with the first touching the electric fence and the last in line getting the shock. 😂
LOL. So right. (unless they are wearing welly's)
@@astra6712
hey vince, been an on and off fan for awhile and i always come back cause your videos are interesting, would you ever make educational videos that show you how to use a multimeter or videos on basic electronics?
Same here - I have at least 2 multimeters, still in their boxes unused, as I don't know how to use them!
Good point about caps on the power board of lots of electrical devices. I have just replaced 2 bulging electrolytic caps on a 32" AOC monitor with a distorted display, chose Rubicons with the same values - hey presto it works perfectly. I also remember the old Sky boxes having a similar problem which could be fixed easily with new caps.
The 3kHz sounds like a display scan frequency or a button scan frequency - in either case it could be a bad/aged capacitor on the power line in the relevant sub-assembly. Visual check the capacitors on those boards and maybe consider changing those out.
Hi been watching for 3 years now and love the content even tho I scream at the TV sometimes 😂.
What might be a good idea is to get a SPD ( surge protection device) which is installed in your fuse board or next to it in its own inclosure which is designed to reduce the effects of incoming surge's from your electrical supply. They are designed to protect the ever increasing amount of DC equipment we all have in our homes these days. They now have to be fitted in any new home or distribution board up grade. They are now quite reasonably priced also. Hope this is of some help and would probably make a good vid maybe all the best.
It did look a bit like the leads shorted when that cap tested okay the 2nd time, which would make it a bad cap. It probably just looked that way because you were angling them so that you could see the gap though.
I'd guess the whine was from nearby interference, as it seemed to go away when you moved the radio. Maybe a noisy switching mode power supply at the workbench.
hi there Vince from Brisbane Queensland Australia, love your videos, very relaxing to watch them all the time as i have been watching about 6 a day to get through them, i would like to know if you would do a video on your equipment or even put what you use at the bottom, thankyou again Shane
Hi Vince, when i have had equipment randomly resetting, it's often a main filter capacitor that can be faulty, allowing too much ripple onto a rail that a microprocessor uses, resetting the microprocessor. However, you would normally hear that ripple on audio equipment as a 100Hz buzz. You could monitor voltage rails with your scope as its battery powered.
From my view of the radio, I could not tell if it uses a switch mode power supply or analoge style supply. Switch mode supplies use an oscillator to convert DC to AC and back to DC. You could monitor the supply rails for ripple and also the 3k tone with your scope. Keep the scope isolated from any external power, and be careful where you clip the ground clip of your scope. Use the x10 mode of the probe also. Analoge supplies normally use a transformer feeding a bridge rectifier then the main filter capacitor. Check regulators also for incorrect and unstable voltage rails with your scope. Good luck.
It's kind of a revisit isn't it? And you gave it yet another life.
Another great video. Best wishes.
I love your channel Vince. Been watching for a while but I rarely post on videos. Please check DC voltage with your DMM on the speaker outputs. When an amplifier has issues with DC offset, they can produce a midrange frequency hum like you’re experiencing. It’s generally larger amplifiers that this happens to. Not chip amps like that more than likely has but still could be something else to investigate.
Thank you Steve 👍
Vince you could have had one of the wires lying against or too close to the DC to DC converter, or lying too close to a coil or antennae connection causing a very low powered feedback.
Now that it seems to be working, it's a possibility whatever was causing the noise has moved far enough away to lose rhe hum.
It would be interesting for you to pop it open, move wires around to see if the noise comes back or not.
I would guess the noise is from some switch mode DC-DC converter. It could also be electromagnetic interference from some other device in your home. But I have to admit it does not explain why you can't see it on the oscilloscope - except if it is not comming from the speakers. The tiny ceramic SMD capacitors can emit sound if they are faulty. (btw: this also works the other way around and they can unintentionally act as a microphone). Also the tiny coils from some DC-DC step converter can emit this kind of whine.
I was thinking it might be coils because of the PS5 coil whine people were complaining off when it first of all came out. Cheers VVerVVurm 👍
Can you still hear the sound if you unplug the speakers?
DC-DC converters frequencies are typically in the range of 50kHz to 500kHz. Depending upon the power supply topology, could cause some harmonics,
The switching frequency (fSW) for most Class D amplifiers is typically between 250kHz to 1.5MHz.
I had a NAD amplifier that also had a high pitched noise. I sent it in twice for repairs, but they did not find any problems with the unit. This eventually turned out to be due to a very old refrigerator from another student on the same circuit.
The 3.1KHz humm you hear is maybe coming off either the internal (switching) powersupply of your internet radio OR from some LED- or powersaving gas-lightbulb ... these bulbs have very noisy switching powersupplies. Also, it's possible your camera produces the 3.1Khz ... so maybe try different lightings (classic filament lightbulbs perhaps) ? or move your camera a bit further away?
Intermittent faults are the worst to fix. I like your methodical approach, but you should take notes of what you changed and WHEN you did them and what sort of faults popped up afterwards... Like I said, intermittent faults can be the hardest to fix.
Good luck and have fun fixing it !
A suggestion would be to scope the supply to the CD, which (at a guess) will be 12V or 5V probably using a separate regulator somewhere on the main board. Monitor both in DC and AC (to see noise) mode on the scope. Would be interesting to see whether 3kHz also occurs at your dad's place. You are suffering with slightly dodgy loose bananas (which seem to be par for the course with those ESR meters)
Capacitors in a PSU are always inferior, Manufacturers use the cheapest things they can.. But if you use an ESR meter that will tell you if they are faulty or not. Now if you are looking for a hot fault We used to use Freeze spray. This was a spray can that ran out at speed and was costly, but a squirt on a faulty chip told the tale. Next was a hair drier. This created fast heat on what you believed faulty.
Comments below tell you to keep one hand in your pocket, this is impractical. People get electrocuted because they knew they did the wrong thing/ Amateurs are afraid, their hands are sweaty, they get zapped badly. Pro,s have dry hands they get zapped, its an oops. . If you fear what you are doing, wear rubber gloves. I fixed PSUs for 40 years, Im still here.
I noticed your ESR Meter showed "error" on the top right corner sometimes - can you really trust the shown measured value if this error appears?
I never noticed that before. Let me mess around with it to see if I can get it to show 'error' again. Maybe my leads or the connection of them is playing up. Thanks for telling me.
@@MymatevinceI believe it’s because you have the ESR meter set to “manual 1 to 10R”. As such it is expecting a value between this range and as the value is less than 1, it is warning of an error.
Try putting the ESR in Automatic mode and the error warning should disappear 👍🏻
@@Mymatevince For what it's worth, I have an identical-looking ESR meter and I've never seen that error. I noticed it in the video too.
@@IamPedroUKi have to agree the error says because less than one r nothing wrong with it.
@@IamPedroUK Nice one, that is really helpful, I've just changed it to auto. I rarely use the ESR meter, but I think I must have accidentally changed it over to manual one day, without realising. Hopefully going forward it will now make more sense. Thanks for commenting 😊
Well done Vince nice fix, my thoughts…. Bad caps on the mainboard ? Or maybe loose screws causing a bad grounding fault, I have weird faults on tvs before due to loose screws
Every summer during the late 90s and early 00s, every time there was a thunderstorm locally, the next day we'd have a steady trickle of people bringing PCs in for repair with blown-up modems and worse, and thus the market for surge suppressors was invented
I'm a former Mindspring support tech. You wouldn't believe the number of people that would purposely pull the power cord on their PC before a storm yet had occasion to call support the next day. No one EVER unplugged their phone cord from the PC and no one ever used the phone jacks on the surge suppressors either. Many a modem got killed even when the PC was disconnected.
I could have sworn you had a component tester, So if you don't, it's imperative you get a
good quality one ASAP, That way you can test Resistors, Capacitors, Diodes, Fets,
thermistors and Transistors just to name some, and depending on what component
tester you end up getting, there are some that will test most Logical & Programable IC's..
I had a Gen 2 Yamaha CD player that finally quit in 2004 or so. I got it in 1983. He probably could have injected voltage and used FLIR, to find the short, and replace a cap or something. I wish I still kept it. Years (decades) later I watch Northridge fix, fix things pretty easily sometimes.
The pitch you are hearing is digital, most probably, from the MCU or other clock bus, when it works or is given a "command" the clock frequency shifts. You might be able to probe and prove this with a scope, I had that same issue with a rubbish set of pc speakers.
What I would suggest if you wanted, is to find where the signal lines going to the preamp are, tacking a set of ceramic caps and then tack them on from signal to ground and see if that remidies it... A lot of rf equipment in the older days needed caps from audio lines to ground or chassis ground to stop spurious harmonics pickup from getting into the audio side of the rf transmitters and recivers... This would usually be a shielding issue but, because these are tight quarters, something could very well be bleeding through.
Good luck Vince.
First of all, Sorry! for the long! Explanation Vince! As it's a switching mode power supply, which is essentially a means of stepping down a voltage to DC in a controlled manner.
This SMPS basically consists of smoothing capacitors, current switches (typically transistors or a combination of transistors and diodes), and an energy storage element
such as an Inductor (You have a row off in the radio)
An example of an SMPS operating cycle works as:
Current switches on the input side allow current to flow through the Inductor, storing energy from the input within it.
These current switches stop conducting while another set begins to do so, connecting the output to the Inductor. Energy flows from that Inductor to the output.
You'll notice how the Inductor is repeatedly gaining and losing energy. This translates to a changing magnetic field, which causes mechanical movement at a frequency.
On the power board of the Radio it will have what’s called a switching regulator. As it’s name implies, it switches electricity on and off very rapidly.
The electricity then goes through a magnetic coil called an Inductor. (As I said Vince! you have them in the radio)
Because of the rapidly switching electric current, the Inductor vibrates a bit, making a very high pitched hum.
Again sorry! for the long comment 😅 I have a Pure Evoke C-F6 Internet radio that looks similar to your fathers radio. You might want to look into one of them, for an alternative. 🖖
Definitely change the new router to the same name and password as the old one. Saves alot of messing around especially if you have alot of devices.with the surge from my understanding it wouldnt blow a fuse necessarily just because voltage is high the current is probably relatively low . High voltage could easily jump a switch aswell lightning strokes are thousands upon thousands of volts 10k volts would jump 1cm.
nice video Vince
It's probably been mentioned loads in the comments now but that 3khz hum is very common, not always that specific freq but it's because of data lines close to audio lines, and/or ground looping in the device OR on any of the lines in your house. Electro-Magnetic Interference!
It's most common on cheaper appliances or those where the capacitors that do the power smoothing are low quality/worn out, those giant caps on the main board are probably amplifier related and for signal smoothing to prevent such a noise in such a densely packed board with power/data lines so close to audio causing EMI.
Replacing those for high quality Nichicon or similar reputable brands, or even a more costly "audio rated" cap (don't fall for audiophile overpriced BS though) is a great option but may not fully prevent it.
Two things: one, your Dad's hearing is likely to be as poor as mine at 3kHz, so its not going to bother him, and two, its an expensive radio, so rather than buy another, get an old iPhone running a music streamer like Simple Radio and connect it to a small amplified speaker. Better, get an amplifier and some big speakers so you can boost the higher frequencies for him.
Great video as always, Vince!
I thought that it is better to replace caps with higher uF but the same voltage?
But in this case the operating voltage does not reach 25V obviously..
About the whine - to me it sounds like a coil whine, sometimes PC motherboards or graphics cards has something in those lines, due to low quality components.
No you should not change the uF of a capacitor as that value will be chosen for that circuit, but putting a higher voltage rated is fine.
It is better to overspec the rating of the capacitor anyway so they last longer and handle unexpected voltage spikes, but a 16v rated one on a 15v power rail is quite close to the limit with very little margin.
You can create a loop antenna for your scope and then move it around the components to see if you can pick up the 3KHZ signal.
Wow great idea
It would help if the scope has a spectrum analyser function.
I get my own personal welcome at 10:13
Hi Vince, I'm guessing the noise is coming from a slight instability in the switchmode power supply.Changing the capacitor in it's feedback/compensation circuit may fix the problem. Probably the current draw is different between the radio & CD player & this is causing the SMPS to behave slightly differently.
Sometimes ferrite cores act like buzzers - to pinpoint them use a plastic hose to your ear. And yes - the buzzing can depend on temperature, humidity, load current +++ .
I asked this digital friend of mine, perple-something, and it said "According to the search results, a CD player can produce a hum at 3 kHz. The hum can be caused by low-order harmonic distortion or magnetically induced hum from the AC transformer. The noise spectrum of a CD player while playing an infinity zero track can also be measured with a 3 kHz or 3.15 kHz signal compatible with many flutter meters. If you are experiencing a hum in your CD player, you can follow some easy steps to determine the type of hum and where it is coming from."
I think it's great that your father enjoys his internet radio. He probably didn't hear it. Husbands filter out any kinda whining.
Seems like a DC side noise. Possibly crossover network for speaker out?
Just guessing, probably resistors for high end sound, vs caps on low end.
Those high frequency noise artefacts are nothing unusual with class D amplifiers. It will have active muting for a period in some input setting changes and start up.
It can also be the digital volume control chip, or more likely the DA converter in the CD player.
I am halfway through the video, but if I suspected the power supply, I would measure the output of the power supply, then use a bench power supply to power the radio and see if it stays running.
Very good job
I had the same kind of noise in a subwoofer. It was the electrolytic capasitors in the power supply. The noise got stronger when I used it for a long time, so it was temperature.
RE 3KHz noise, your scope is displaying a notch at 3khz but also several sidebands at 10Khz and higher, all decaying as the frequency increases just like a radio signal would. My tuppenceworth would be that it is interference from the LCD display or key scan matrix multiplexer. Try holding one of the buttons down and see if the 3KHz disappears or at last changes.
Thanks Joy Of Fix 👍👍👍
Alright governor
I recently had to work on a scanner that I have here that had a garbled speaker after years of use and upon opening it I found a capacitor that had blown that was a 35v@2200uf of which I replaced and it restored the speaker where it was operating again where you could hear thing clearly. Most of the time when it has anything to do with the speakers it’s a capacitor that has gone bad. In my case it was garbled when it made any sound. I replaced it with a 50v@2200uf and it works and sounds great again. In the case of a humming sound that may be also a capacitor or a ground problem or the transformer maybe going out? Power surges of any kind will burn up the circuitry in devices so use surge protectors on every line in my home. There are 2 types of power surges: brown outs and a direct power surge. Each is different and does different things to electronic devices. Brown outs are power surges that go on and off over and over and each time they do they put a lot of stress on the system. Power surges are direct and they come in on the line at any voltage and can fry everything in the unit.
Regarding the 3kHz whine, my first investigation would be the SMPSU, look at the data sheet for the IC in the power supply, I suspect that it might run at that frequency or a harmonic of it.
After that, I'd look at the other digital ICs datasheets and what they are clocking at.
I suspect that the whine will be either bad capacitors, poor screening or poor earthing. These problems could be part of the actual design that was never picked up at the prototype stage, it does happen. The digital and analogue ground connections have to be separate for this very reason, and if these two grounds do get connected, either physically or through the failure of a component, then a symptom would be the sound of the digital signals in the audio section. As it's a constant whine, I would suspect a clock, if the sound was like old Internet dial up, then that would most likely be interference from data.
Vince ruled the smps out as cause of whine when he powered the unit from his bench supply and even if his bench PSU is a smps the chances of it having the exact same frequency of interference down to the Hz is highly unlikely
likely servo clock on driver board and always been there but to a lesser degree when new
could the hum be a signal wire routed too near the lcd display? (check the board for a 3khz crystal around the lcd - see if thats the frequency that the logic works at)
If the noise comes back, and as it seems temperature related you could use some freezer spray on some components and see if the noise goes away
Hi Vince, great video as always. I’d like to ask a question about copyright strikes. Forgive me if this has already been asked but if you’re not allowed to play music which is copyrighted, how come you can say named brands which are copyrighted? How come you can show gameplay footage which is copyrighted? Also there is music in games which is also copyrighted. Again, sorry if this has been asked before
Yep B&W had a well known issue that the high pitch noise would come first then crackling then nothing and that was a capacitor that caused the issue
Dad listening to Irish radio is a W
there is an excellent channel called Mend it Mark.. I highly recommend it if you want to feel totally inadequate about your repair skills... But I bet if you asked him he'd give you a good idea of what it is.
I've had to deal with the aftermath of a lightning strike one time. Everything was protected with anti-surge devices and almost all of them survived. The point that failed was the phone connection for the fax in the printer. That then made the printer live and then the switch via the ethernet cable. All were fried. The phone line had become welded in the junction box however the router survived.
Looks like the noise might be coming from your external power supply. Audio amplifiers are sensitive to the kind of noise generated by switch mode power supplies. The original board probably takes that into account and do proper filtering, that the external one doesn't. Sometimes even some noise on the power lines can travel into the audio amps (mostly when the device uses normal transformers).
I was wondering if the hum was introduced by some other external device onto the radio. Maybe some chip or exposed wire was acting like an antenna. Years ago i had a CD player that had a hiss when i used it in the Kitchen because there was a fluorescent bulb in there.. Was fine in every other room in the house and was only the one cd player.
Does the noise resume in certain locations?
As a musician, I get noise like that around certain lighting fixtures when I utilize single-coil pickups.
My dad lost a TV and Satellite TV Box to a bad storm. I think his whole house is Protected now.
I don’t know how useful this info is but my ps4 used to make a squeal like that on and off and it was caused by a coil (known fault on ps4s)
Possibly the coupling circuit form the CD audio output through to the Audio amplifier out has a faulty component in it, eg capacitor, coil, or resistor gone high ?
7:17 British standard safety test. If it don’t burn and you can still remember what time the pub opens, all good.
First thing I though was to check out that transformer on the power supply. I have had high pitched whines and intermittent power issues caused by damaged transformers, and when you switch to CD it could be drawing different voltage to power the CD drive and put more load on the transformer and cause it to whine.
Hey Vince- Get the Peak Atlas ESR70 Gold. You won't regret it. They're UK based as well.
You can get electronic component freezer sprays, which will let you cool an individual suspected component. Alternate with a soldering iron to confirm. I have just bought a handheld oscilloscope to trace signals though a circuit, maybe you could do the same by introducing a signal to your unplugged radio, and try and trace it through.?
I just use a can of computer duster turned upside down.
Just a note of caution, I really wouldn’t lean over something that is open and plug it in. Maybe move your workbench sockets?
Did you have a cd in at the time of it humming? Or if you didn't di the hum start up when you first booted the radio and selected the cd then die down? My thinking is it could be the motor to spin the disc or the one to move the laser.
For the 3k hum I would suspect improper shielding and an environmental source. When you tested it the 2nd day, you were not at your bench. It being more prevalent on certain source would tell me a design flaw that isn't creating a proper bias filter. Ideally on the input phase they want a input capacitor, and bias resisters. Also a certain degree of shielding to prevent EMI from affecting low level signals. It could also be a faulty 5v or 3.3v regulator on the digital circuits, with a bad capacitor I'm those sections. I would look for ac component of your DC 5v or 3.3v rails. There is most likely a step down converter in the main circuit that powers the digital electronics. And 15v is a common voltage for audio circuits. Often even +/- 15v in pro audio configurations.
Thank you Rob 👌
@Mymatevince also if you get a chance to look at it again, check the mov's on the power input. It's possible the lightning took one or both out and is causing the unit to be improperly grounded now.
I think that noise could be an internal clock crystal running at about 3Kz..it's quite common to find xtals at about that frequency in microprocessors
Has your Dad been listening to Paddy McGinty’s Goat ?
That can cause problems.
Total guess work here Vince as not an electrician, but possibly be smoothing caps in the radio. or sheilding not covering what it is supposed to that is causing the whine. Or RF Interference like not having a polo mint type of choke/magnet type of thing on the speaker wires usually want it close to the power supply end of the cables to stop the interference if it is not positioned there, there is more chances of interference
my guess would be the choke, as electric causes a hum, and that can easily pass over to the speakers wires.
3 khz is a very high tone. Do you hear a very high tone or a hum? And do you also hear it when a CD is actually playing? The input of the amplifier might be floating when the CD is not actually playing, causing the hum. Normally we find high frequency hums with a little antenna connected to a spectrum analyzer, we just move the antenna over the board and even around the room. As suggested, also check other supplies on the board with a spectrum analyser or scope, especially near the CD section.
Thanks Kris, once my ears tuned into that high pitched hum I could here it even when the CD was playing. If you walked into the room you wouldn't notice it straight away, but once you were aware of it you couldn't unhear it. It was really annoying!! 😂👍👍
Does the noise also occur on headphones too ? Most likely DC leakage. Some of those caps are most likely leaky too.
I reckon the noise is from a spinning pin in the cd player - the motor can be producing the noise at a certain frequency depending on its spin rate.
I think alot of amps these days are wired to be on while in stand by so they make the hum till the source starts outputing such as putting in a cd a hit play check if hum is there while cd is playing.
Whine is probably a harmonic from your pwm supply. Find out what the output voltage is and set your bench supply accordingly, I bet the whine goes away when you use it. Blow through the pwm pcb and change all the caps if it does. Failing that try the caps in the amp stage.
I have the original LEMEGA version of this radio Vince ( not the John Lewis rebrand ) . Mine is called the M5 ..and I notice that mine has spotify built in , also all my buttons are on the front of the unit , not on the top ..So far so good
My only goal in life is do become an old dad that listens to the same radio station every night on the same old radio and have my son fix the wifi in my brain chip (because it's gonna be in the future) every now and then.
Maybe the frequency is being generated from your studio lighting during the repair?
The high pitch noise is probably "amplifier self oscillation". Check the electrolyte capacitors in the amplifier section, if that's not it. Then one of the semiconductors or IC's is dodgy.
Must be something shorted.
Nice
My Pure radio has a Frontier module of a similar type, it makes electronic noises with the backlight at a full brightness, it is not really a squeal though.
I'd go with an active part... transistor thermal runaway or DC on the output of audio circuit for the hum.
that 3k signal likely was getting generated by a wire carrying audio getting too close to the transformer that drives the LCD screen. and when you pulled it apart it allowed that wire to come to rest in a slightly different spot that it is now far enough away from that transformer.
So i went to check the original video was posted April 2020. So your original fix lasted almost 4 years.
I wonder if the 3101hz is coming from something noisy like a light or something in the workshop? I wonder if he took it back into the workshop and that is the only place it makes the noise?
I noticed a number of capacitors on the mainboard along with some coils. No doubt the main board has it's own power supply to create lower voltages. Same game all over again.
I was thinking coil whine or some sort of grounding issue you fixed by taking it apart and putting it back together?
Hi Vince I think it's on the power supply as it works on high frequency and then needs to be filtered before going to the rest of the board but that is a common problem with switching power supplies it would be better to use a linear power supply like a transformer that can put out 15 to 16 volts DC but it needs a lot of current at least 2 amps but the size of the transformer will be massive as due to why it runs of a switching high frequency power supply other thing to check is the voltage regulator chips
Another thing to note is that the amplifier is also powerd by the same power supply that also runs the rest of the electronics , I've notices that when I connect an amplifire with say Bluetooth module to one power source the same noise occurs the is definitely sorting wrong with the DC to DC buck converter IC may check that out
One or more capacitors may have been bad or maybe a solder joint wasn't always making good contact. If it wasn't making good contact part of the time changing the caps would have solved the problem even if the original caps were good.
I wonder what an oscilloscope would reveal about that Oscillation?
And is the lil sucker traceable or not? As it sounds like an inductor
and or a capacitor associated to it is on the verge of failing, in this
case I would suggest working backwards from the speaker output
to the first inductor "if Amplifier is Class D" and any connected
capacitors so on and so forth along the signal connected outputs
and inputs to each stage/s, lifting the connected capacitor leads
where it should change the pitch or remove the oscillation therefore
pinpointing the problem.
*Addendum*
If that oscillation returns when the device is back at your fathers,
then the location obviously has RF noise pollution which BTW is the
very reason why there are strict rules in the manufacturer of
devices.
A radio that can tune to the annoying frequency will confirm it's RF
pollution..
I remember the original fix👍👍
Did you connect the radio whit a cd player, and hear the humm ??
hi there again Vince, do you have any merch ? as i seen you had a cup/ mug that had thankyou inside it ,it look good ,is this your merch, just interested in seeing if you have a site and all so i went to your web page and the eBay link at the bottom does not work ?