That was a filter cap. Mean to filter noise from the audio. It wasn't the wrong capacitance it was "Leaky" meaning that it was letting noise through. Sometimes when filter caps heat up a bit it can help "seal" the leak. Also sometimes if you ground them out using your finger you provide enough capacitance to aid them in doing the job. Anytime you have popping like noises on audio circuits it is probably faulty filtering. You can see this on an oscilloscope usually. Also testing with a component tester/meter can be enough if you already know where to look.
Could it be, that it's "leaky" because of the lower capacity? After it's fully charged, the overcharge in dependency to the lower voltage specs of the wrong capacitor causes arcing. The arcing causes the "plop-noises" everytime it arcs.
The capactitor was intermittently faulty, whether leaky or some other type of fault. I actually don't believe it was leaky as much as an intermittent faulty connection internally, as leakage usually increases with heat. Decoupling capacitors such as these are not critical as far as the capacitance. You can be off 10 or 20% and they will still do the job
Yep, I was thinking the same. The frequency of the noise was changing with amplification rather than turntable speed so you should be able to ignore the motor and cables. I was thinking capacitor but I would not have guessed the smd ones. That said, once you knew it was one channel only it shoud be simple to trace back all the amplification circuits to find the pairs of caps and, even measuring in circuit, you should be able to find a badly unbalanced pair.
Brilliant!!! Haha @ the IPA written your head!! I suspect that capacitor had a fracture in it - what was probably going on is as voltage was passing across the fracture, it was intermittantly passing over, and then stopping, starting to pass again. Caps like that subject to failures like crystals, ie. they can fracture, and they can be affected by vibration and they can oscillate too (through vibration). I am assuming those caps were coupling the audio. To fault find that, I would have scoped - compare one channel to another, on that channel you would have seen the spikes as you hear them, and then narrowed to something connected to that point.
The clicking is the “clipping” of the top of the sinusodal audio wave, e.g. the top of the audio sin wave is being chopped off at the top, or clipped giving a square wave, (castellations) hence the on off of the clicking noise, which you would definitely see on an oscilloscope. Love your connected by the way, I’m a mass spec & HPLC engineer here in Ireland and would love to take you out on some of the breakdowns us guys go on over here working out the flow of electrons through the instrument, or lack of 🙈
Yes. I think that was due to inadequate capacitors across the DC suply. Something loud and short could drag the voltage down and it would reduce the maximum audio output amplitude.
Yes, soon as I heard I said same. You should see it on a scope but motorboating capacitor is the term. Only us older guys would have felt the pain and always on audio amplifiers. If it happens in an if or rf stage of a wields, then that’s also a challenge. Especially on a superhet Circuit.
!00% agree with the motor-boating description. I believe the cap was either poorly connected at one end of its own connection pad. Hence the heat making things expand and work. Or cracked and heating it made it temporarily connect. The reason I’m sure it was this is the fault stayed when you completely removed it.
You prob won't see this Vince, but also in the early days of PS3 YLOD (Yellow Light Of Death) repair strategies, heating up the tantulum capacitors also had the effect of temporarily fixing the YLOD fault. This led to theories that the heat was reballing the chip, when really it was just the caps that were the issue. Great vid as always :)
it actually turned out to be something like a mere 3% of the diagnosed cases. turns out its mostly the solder between the gpu die and the interposer, or the interposer and the main substrate pcb failing due to the heat cycles screwing up the connection. none of which is fixable, without replacing the gpu chip itself.
@@kenabi ah thanks for the info :) I've got an old PS3 YLOD and some replacement caps, so I'll give it a shot, but steel myself fir the chance it may still not work! Fingers crossed...
@@johnparker007 The channel "RIP Felix" (@ripfelix3020) has a view on it from around year ago. I don't know if there's been another or more info. _"A PS3 Story: The Yellow Light Of Death"_
@@johnparker007ripfelix on youtube has made a great analysis video about the ps3 ylod and indeed its not the caps but the gpu underfill that due to thermal expansion makes it so that the gpu die gets discconected/moved from the substrate and that caused the ylod. I can link the video if you want
That RC combo on the output is called a Zobel network and it's there to add a load to the output at higher frequencies (where the speaker impedance starts going up). Problems with the Zobel can upset the feedback circuit causing oscillations. How to fault find ? Replace the speaker with a 8 ohm dummy load and check the amp output on the scope. It would have been ok (because the resistor has no inductance and thus has flat frequency response). That would have been a clue pointing to the Zobel.
Hindsight makes it easy to say do this or that. We want to locate the fault not because its economical, but for knowledge and experience improving, honing our skills. My lesson from this excellent repair is next time, disconnect one speaker in the initial observations, could have pinpointed it to one of the stereo amps. Great work.
It has been a minute since I have watched one of your videos, honestly didn't see you were posting as much as you are. The quality has gone up quite a bit, fantastic job! Always nice seeing a channel I enjoy growing. Keep it up man.
very well done vince like you my first step after checing voltages would be to change the chip. after that i would of used freezer spray to try and pinpoint the fault .
Nice Job Vince, tenacity paid off. I thought a capacitor or something on the power input side and would probably have been the cause, but I also suspected the chip too. You could possibly have used the scope to find the area where the noise was coming from. Great Job as always👍
Nice catch ! I work on a lot of audio and I don't know how you found it without at scope !!! With faults on audio you usually have one channel thats ok so its a simple mater of following a signal around. I would have stuck a known signal, usually 1Khz at the input and taken it from there. That cap was almost certainly a filter so upping the capacitance won't hurt but the 10nF is a Tenth! of what it should be. The speed of the clicks is governed by an RC network thats a cap and res combination and with the circuit diagram you could work out the clicks but who cares. Essentially you got a bit lucky ! and in no way am I dissing you but thats your determination. Without a scope I would have binned it and chalked it up with the rest...cheers
You asked how else could that be found?... A tool used in radio repair called a "Signal Tracer". It is used to find noisy or open signals. One probes an audio source from input to output to find noisy transistors, tubes (you call 'em valves), and faulty capacitors. That capacitor you replaced would be referred to as a "Coupling Capacitor" where it would allow an AC signal of a specific frequency to pass through. What was happening is that in that circuit was being amplified. Any amplifier will amplify everything... in that case likely some type of audio mixer... and the pulse of the mixer was not being filtered or blocked by the faulty capacitor. Thank you very much for your "Fix It" videos. I also enjoy fixing whatever I can. Greetings from Oregon, USA.
Oh yes. Building your own signal tracer was a rite of passage in the 80's. Great piece of kit as simple as using an oscillator injector and an amplifier and earpiece.
The reason that your record player was making that popping noise, in my opinion, was that the faulty/ wrong value capacitor had turned one channel of your audio amp into a blocking oscillator! Full marks for perseverance, though!
I will love to find a great repair man like you where i live, i want to repair a Arcadia 2001 console i buy some years ago, but there is not fix videos of this console and i don't know where to start looking how to fix it, also, the components will probably be imposible to find in my country anyway. Great video.
Hi Vince, I've heard similar faults in audio equipment and there too was the fault caused by the capacitors. Next time you deal with faults having similar behavior, you will know - A capaciThor is at fault. You just have to find which one. Other than that, good job mate!
I would always use freeze spray before using the hot air. I fixed hundreds of faults that way in the '90s without even referring to the service manual. Always aimed at the semiconductors in those days. We didn't have SMD MLC capacitors back then so it's interesting that they are also prone to thermal faults. Having said that it is probably more likely someone at the P&P factory replaced a mislaid 100nF with a 10nF at the board rework station.
My money was on a capacitor from the beginning, just from the sound and the fact that it changed when the volume (voltage of the pot) changed. My layman explanation would be that the smaller capacitor wasn't able to absorb the fluctuations to filter out the noise, kind of like if you were using a really small funnel to fill a bottle, from an erratic tap, and you get water splashing out of the funnel when the tap spurts, like when there's air in the line. I'm not an expert by any means, and I might be totally off the mark, but this is what my brain thinks!
the capacitor(s) must be used as a noise filter, so if one capacitor is only 10ohm then more noise from e.g. the motor can get through, and with a 100ohm it filters out more noise. yes there are many ways to make a noise filter today😅, I hadn't thought in that direction either, but you can just see how such a small capacitor can wreak so much havoc.😂thanks for teaching us about such a problem and where that problem can be on the circuit board🥰
cheramic capacitor easily gets micro cracks, especially when the pcb bends a little. you measure short circuit or open. very common problem in mobile telephones and laptops
Yet another great fix - I am always amazed by your persistence and ingenuity. I guess the "swearing" moments are cut out with edits. Surely there must be an odd moment where you just think !!!!!!!. Come on Vince you are human (aren't you, not AI!!!).😉😉
Indeed strange problem. In the 80's there was probably much more testing and quality control was better, so very very few faulty items ended up in consumer hands. Now it seems there's a lot of faulty items, and QC is a joke these days.
Generally, I was taught you MUST remove a capacitor in order to get the correct value. You pretty much confirmed that. I admire your determination to find the fault. Using the heat probably expanded the micro- crack in the cap. By pushing on it with your finger, you were manually flexing the ceramic. There are more advanced ways of finding a faulty capacitor, but hey, it worked. Sorry you had to spend hours figuring it out, but that's always the process of learning anyway. The next time around will take minutes.
Different ceramics used will have a different response to temperature, some types (NP0, C0G) are designed to remain fairly constant and are generally up to about 100pF or so, although they can be had up to 100nF or more, depending. These are found mainly in timing circuits or the loading capacitors adjacent to quartz crystal units. Another group (X7R, X5R, etc) are usually used for decoupling, generally around 100nF to 10µf, they're not as stable, but still usable in non critical applications. Then there's the ghastly Y5V and Z5U grades which have tolerances from +80 to -50% (or something along those lines) depending on how you look at them. These change with both time and temperature, but have a higher dielectric constant, meaning for higher capacitance value in less space. Gotta love tradeoffs. I think that specific capacitor is just plain bad or has somehow been internally damaged or otherwise defective, but working with pick and place machines, sometimes they'll mispick a component, which ends up at a funny angle in the tape, then gets flung out when the feeder advances. Sometimes they'll end up laying on the board, falling down inside the machine someplace, or landing on top of an identical-appearing (to machine vision) component in an adjacent feeder, then hoovered up and placed someplace on the board where another part was intended to go. Sometimes the carrier tape that the parts come in is just plain garbage *cough*Yageo*, and parts will end up sticking to the cover tape or getting popped up out of the carrier tape by an irregular bottom layer underneath, causing all sorts of mayhem. If you have enough familiarity with the boards you're working on, the specific parts you're using and the intricacies of what they look like, and are used to examining these things up close for several years, you'll notice it almost immediately if something isn't right.
Those tiny ceramic caps are a PITA in electronics longevity. We used to have a plasma TV which stopped turning on unless you let it rest for a few hours, which is a telltale sign of caps usually. Got quoted almost the price of a new telly at the service. But swapping two of those specks of dust on each of the sustain voltage generator sub-boards got it back to life! Until I tried to repair a broken HDMI port and fried the CPU some 10 years later :-)
Thanks for the video. I would try and trace the noise back from the speaker to the source using a cheap signal tracer, like the velleman, k7000. It works wonders for me.
Hi Vince, I don’t have much to contribute in terms of technical help but I think the returns label says Vinyl (misspelt as Vinyle) Scraping. Fairly new viewer here but catching up rather quickly. Keep up the great work!
It depends on what the circuit is and where in the circuit it is. Without a circuit diagram, we can only speculate. Reverse engineering the amp circuit would show what the cap's application is. the stuff we learn from repairs of this stuff is far more rewarding that doing crossword puzzles :-)))
You could fault find this with a scope by measuring the signal of the input of the amplifier and then gradually backwards until the signal from the needled. You could find after which component the noise appears.
DC decoupling caps probably. The scope would have shown the spikes that you were hearing most likely on the DC rails. With high gain circuits like this I would likely have paralleled up any capacitors on the input side to test the effects. Sometimes even the parallel capacitance of the scope probe will affect the circuit, depending on frequency. Many types of caps are affected by temperature, as you discovered. Still a good fix though, albeit a substitution marathon!
Vince, I think the fault stated on label was supposed to read “Needle Scraping”. I also saw another commenter interpret it as “vinyl scraping”. Both are possible interpretations.
Prolly signal probe would be way better than the oscilloscope, you could check the signal as it goes from the cartridge and hear where the popping starts. Look for some schematics as they are easy to make. I'm long overdue for making one for myself.
that kind of noise ive found to be capacitor faults so i would have been looking for something wrong in that regard right away, the fact that it was only one one side would have had me looking for a paired set with one being different as for the why, i dont actually know for sure but i suspect it has to do with the smaller cap being overcharged, iirc resistance goes up as the the charge goes up so an overcharged cap would behave close to an open hence why removing it made the click worse. my guess is that the signal is supposed to go through at a set rate but it cant if the capacitor is saturated and heat increases conductivity which temporarily resolved the issue the part im having a hard time sorting out is why the clicking, i would have expected no sound at all on that channel instead or being choppy/quiet
worth noting that i would not have found this issue, i dont touch smd components and always assume they are okay, i dont have steady enough hands to do that kind of repair so if thats the issue then its junk and i cant do anything about it
An idea that I just had: Maybe using your oscilloscope you could've traced back the audio signal backwards from the output until you find a place without the pops.
@@Mymatevince Instead of a scope you could use an old earphone you don't care damaging if it lands on the wrong spot in the circuit. That however would also need you to have something playing on the turntable to have a reference signal...
Motor boating is caused by the presence of the output signal on the DC supply line. This couples to the input causing the amplifier to become unstable and oscillate. The shunt capacitor acts as a filter, combined with a series element, to supress this unwanted feedback.
I think it says Vinyl Scraping - The I ,N and A match in the word scraping. Whoever wrote that did not know how to spell Vinyl.. so they did it phonetically... Vin-ALE :P
When you add heat it expands the capacitor, in turn increases the capacitance by increasing the space between the plates. (Lessens the chance of shorting) Class D style amplifiers are make sound by PWM, so they are very noisy and need a filter network to clean the signal to produce sound rather than erratic noise. When in doubt about values, check the spec sheet, in most cases the circuit will be a near copy of what is in the sample circuit.
I would have used an oscilloscope to first test the input and output of the audio amplifier IC, then you would know which side of the circuitry was at fault, secondly low-frequency popping sounds are always faulty capacitors which smooth out voltage spikes which cause audio pops
That was a faulty filter cap. You can hear it in how when you changed changed power supplies the the oscillation changed. I would have troubleshooted with an oscilloscope going from the speakers to the board to check the components as I progress backwards from the symptom.
Hello Vince, thank you for a not only entertaining channel but a very informative one as well. I used to be a TV engineer years ago and I take a particular interest in your repairs. In my day we didn't have IR cameras or even hot air devices, in this particular programme I was surprised you added more heat to diagnose a fault that was caused by or created heat. By experience this can sometimes lead to a positive result but can also exacerbate or mislead. In the past we widely used "freeze sprays" to find these particular rogue components, in fact as soon as I started watching this one I muttered to myself that it was a capacitor fault. Are freeze sprays still available do you know? Another tool I used was a signal probe. We'd make one up ourselves, a small oscillator set to either an audio or RF frequency and touch it to different parts of the circuit to assess the output, either audio or to an oscilloscope.
aaah.that's motor boating.low frequency oscillation caused by poor DC decoupling on the power rails.usually solved by a 100uF and 100nF capacitor in parallel and then series with a 10 ohm resistor across the power rail as close to the IC pins as possible.
the cap is part of a zobel filter it's purpose is to stop amp oscillating with long speaker leads with an Inductor at the end I'd speaker coil. cap is in series with resistor typically 4.7 to 10 R
There seems to be a good percentage of Bush faults , i remember must be 50 years afo my sister had a Bush music center and every time a taxi came past you could hear them on their radio even if it was playing a record 🤣
Yeah, MLC capacitors like that are known to be relatively fragile, they can fracture internally from many different causes (thermal stress, physical damage or something else). Your capacitance measure for it is all over the place which is the signature of cracked MLCs so I don't believe the pick-n-place used the wrong capacitor. This is likely also what caused the crackling, it was switching between various states with different capacitance and quite possibly either "short" (resistor) or "open"! I agree that it was very likely faulty from the factory, but I think the reason was either the MLC being pre-cracked, the pick-n-place machine cracking it or thermal stress. A proper QA would pick up the error but given the likely price-bracket for this item I expect there was little or no QA. Using heated air like you did can also cause MLCs to crack like thus but it's rare and the error was clearly pre-existing so we know that wasn't the case here.
Well done Vince, you’re like me a dog with a bone lol… Don’t heat up components with a soldering iron on mains power supplies it tends to blow the electric lol, I touched the top of an electrolytic capacitor that was on the hot side it let off a massive bang and a flash and the electric went lol 😂 Strange that it didn’t do it when you changed the chip, but then maybe the cap had heated up when the chip was changed 😊
To keep track of small components just use scotch tape. And you can write the values or whatever on the tape. My problem is that my bench will tend to accumulate various pieces of tape that I occasionally throw away.
in circuit capacitance should read the same on both channels would be a good way to find it. The clicking only got fast when you took the one cap off the good side. Maybe they both were clicking then and out of phase so it just sounded faster. When you removed the bad cap it still clicked.
It would be difficult to fault find without a spare working unit but not impossible. As the problem was only with one channel you can at least swap components between left and right channels until the fault swaps to the other channel. I would Google for the datasheets of each IC and work out what pins did what and by process of elimination work out the audio path and swap components on left and right channels until the fault was found or I gave up because it's not really worth the effort. If you stick at it you can always find the fault (not always fix it though), it's just a matter of time and determination. On the point about the faulty capacitor, it could be a wrongly picked part, but most likely is a failed component. Ceramic capacitors are constructed in layers, these layers crack with stress and the part changed value, becomes leaky (electronically) or shorted. It could have failed in actual manufacture or during storage or at the actual time of assembly (pick and place) or at any time after that. Also how the capacitor read on your tester doesn't necessarily mean that is it's actual value when in use and voltage or signal is applied to it. At that point it could be open circuit. Testing a component can really only give you an indication of failure or loss of performance. Try fitting a 10nf capacitor and see if it makes that noise again- that's the real way to find out - by experimentation. If it makes that noise you know it needs to be 100nf or at least greater than 10nf, if it doesn't make that noise you can assume the original capacitor was open circuit and the reading on your meter was false.
Capacitors can act weird when heated up(chabging capacitance/esr/resistance), and surely when its faulty! The capacitor was probably filtering things or it was going to the input of the amp/opamp
Vince does the chip have a number? I would try to figure out what it does. Analog electronics isn't all that bad and often of an opamp is involved it can explain what the capacitor is doing. My guess would be that it was in a feedback circuit of an opamp and perhaps not filtering significant signal out thus overloading the amplifier. That could explain why it was heating up. The feedback circuit controls gain, otherwise it can saturate the output.
The down side to testing those capacitors with those little battery type readers is that if your not testing them close to their rated voltage, many times they'll read as good when they are not. I use a heathkit IT-11 that I refurbished.
PMSL. This is trolling for sure. I know you must be a fan of Mr Carlsons Lab. Low voltage MLCC's are definitely prone to different voltage and frequency curves and so the datasheet has to be referred to. I would suggest something like a DER-EE DE5000 is more appropriate than something designed for 500V caps from the 1940's.
There was a time when you would have tested all the caps first. Measuring them in circuit might not give you an accurate reading but you can still compare the left channel to the right one. That might have shown the fault. MLC capacitors like that are very fragile. Just the heat from soldering them can sometimes cause them to crack. They often fail short circuit, but not always. Sometimes they fail open and sometimes they drastically change the capacitance value.
Ah, the wonders of tiny ceramic capacitors. Although they may have fitted a wrongun during manufacture, they are easily damaged by spikes, vibration and heat (not that pick-and-place and reflow would ever introduce such anomalies). Fyi, I would ask for your money back on that tattoo. You need an NF (gold plated) capacitor book.
The popping was clearly a cap, and since it was happening at the speaker you backtrace from there. Unplug one speaker and then the other, and within a minute or two you will find the culprit.
for £30 retail it's amazing it does anything at all. Even it wasn't faulty the best place for it is the bin. The cartridge/pick-up/stylus/needle is going to ruin an record it touches.
Vince, that is not a record player, I wouldn’t dare put my precious vinyl on that junk, its best used as a pedestal for the missus to stand on when her heels are just not high enough, 😂😂
Some stuff being diagnosed can be a hair pulling event , I've had a few Cobra 29 GTL in the early 90's the 10.240 Mhz crystal legs were eaten away by the board glue ....
Missed clue was the repetition of the noise. Faster when TT rotation increases. Capacitors are probably in the filter for the servo motor pulsing. IC nearlby would be a servo driver chip?
Could they have meant 'Vinyl Scraping'? (sorry just read that someone else got it already lol). Good job on the repair, lucky you had a spare to compare.
Capacitors are often used to improve the quality of sound, image or signal. A computer can for example start without a capacitor. In troubleshooting. You can try removing a capacitor temporarily. But in this case it whould not tell. Maybe with a better PSU. Schematic and measuring not possible either. It should be possible to figure out what kind of capacitors is necessary depening on other components.
ok here's my best I have fact checked this as well as i can but please some one tell me I'm wrong if I am. 1.Temperature changes can alter a dielectric material’s properties, such as its permittivity and dielectric strength. Permittivity, which is the ability of the dielectric to store an electric charge, varies with temperature for different materials. For instance, some materials exhibit a decrease in permittivity as the temperature increases, resulting in reduced capacitance. Conversely, other materials exhibit an increase in permittivity with increasing temperature, causing an increase in capacitance. 2. I would imagine a scope would pick this up with no issues at all as its causing noise in the system with the correct settings you would see the audible pops on the scope using it to trace the issue is another thing altogether but you could trace if the noise was occurring before or after the amp but seeing as the volume nob effected it its more than likely the latte. 3. As for the difference in capacitance if these caps are used for noise reduction after or before the amp the tolerances etc matter way more than other uses of capacitors. Personally i would think the cap was faulty and the rating is a result of that rather than it just being higher rated but im unsure of this can can't find a good answer on line.
22:34 - I would use simple Kelvin probe/4Wire (Made of LM317 and USB power) to go across SMD capacitors. Then chart them from good board and check them on bad board. I believe it would take 30 minutes and you have written data for next repair when you dont have known good board.
This is a situation where you have to becareful not to assume. The LIR doesn't indicate a faulty chip, just a warm chip. High voltage can cause a chip to get hot, but the thing the digital meter won't show you is the ripple on the voltage, which can also cause those chips to get hot. The digital meter isn't sensitive enough to show the ripple on a DC voltage. Those SMD caps, especially cheap ones, can be problematic and they are usually used as decoupling caps in this type of circuit, which acts to stabilise the voltage to the chips. The capacitance is not an issue with decoupling caps. They can be off 20% and still do the job. I very much doubt the wrong capacitor was picked up by the pick and place machine. It is actually a faulty capacitor. That's why the hot air affected it. If you have an oscilloscope you would see where the noise is coming from. You can also use analogue metres that can respond a lot quicker and allow the fault to be seen. Ultimately, I think that capacitor being faulty was causing some kind of oscilation in the circuit. That would explain the variance depending on volume level. To do further testing, you'd get a spec sheet for the amplifier chip, which often will tell you values of components for standard usage. Often the manufacturers of the chips have a basic schematic of their recommended circuit for use. Given the price of those record players, a lot of places would not bother fixing them because half an hour of time on it is the price of going out and buying one new.
That was a filter cap. Mean to filter noise from the audio. It wasn't the wrong capacitance it was "Leaky" meaning that it was letting noise through. Sometimes when filter caps heat up a bit it can help "seal" the leak. Also sometimes if you ground them out using your finger you provide enough capacitance to aid them in doing the job. Anytime you have popping like noises on audio circuits it is probably faulty filtering. You can see this on an oscilloscope usually. Also testing with a component tester/meter can be enough if you already know where to look.
Interesting, that makes perfect sense. I think you've got it!
Could it be, that it's "leaky" because of the lower capacity? After it's fully charged, the overcharge in dependency to the lower voltage specs of the wrong capacitor causes arcing. The arcing causes the "plop-noises" everytime it arcs.
@@flusensieb244 yeah but it was acting flakey on the meter so not likely just the wrong capacitance.
I used to service TAM machines and that exact fault was known a faulty Bach of cap was suspected at assembly stage
The capactitor was intermittently faulty, whether leaky or some other type of fault. I actually don't believe it was leaky as much as an intermittent faulty connection internally, as leakage usually increases with heat. Decoupling capacitors such as these are not critical as far as the capacitance. You can be off 10 or 20% and they will still do the job
for the first time in about 40 videos of yours that I've watched in past week, I paused the video when requested and went and to make a cup of tea. :)
My guess was capacitor because of the time based oscillations. Just learning about circuits watching you fella's, so a win for both of us.
Yep, I was thinking the same. The frequency of the noise was changing with amplification rather than turntable speed so you should be able to ignore the motor and cables. I was thinking capacitor but I would not have guessed the smd ones. That said, once you knew it was one channel only it shoud be simple to trace back all the amplification circuits to find the pairs of caps and, even measuring in circuit, you should be able to find a badly unbalanced pair.
Good find and well done for stopping up late to find the fault and not giving up 👍
I think it's fair to say that the return sticker says 'vinyl scraping', which is probably how they described the noise :)
Well deduced! Thank you
you beat me to it.
@verschup ah well. Better luck next time mate!
I think its says, strange scraping 😅
Beat me too it lol
LF instability - "Motor boating" we used to call it. Usually unwanted feedback often via teh supply lines, that capacitors have not removed.
Brilliant!!! Haha @ the IPA written your head!! I suspect that capacitor had a fracture in it - what was probably going on is as voltage was passing across the fracture, it was intermittantly passing over, and then stopping, starting to pass again. Caps like that subject to failures like crystals, ie. they can fracture, and they can be affected by vibration and they can oscillate too (through vibration). I am assuming those caps were coupling the audio. To fault find that, I would have scoped - compare one channel to another, on that channel you would have seen the spikes as you hear them, and then narrowed to something connected to that point.
The clicking is the “clipping” of the top of the sinusodal audio wave, e.g. the top of the audio sin wave is being chopped off at the top, or clipped giving a square wave, (castellations) hence the on off of the clicking noise, which you would definitely see on an oscilloscope.
Love your connected by the way, I’m a mass spec & HPLC engineer here in Ireland and would love to take you out on some of the breakdowns us guys go on over here working out the flow of electrons through the instrument, or lack of 🙈
No it isn't, the video clearly shows that the noise is there WITHOUT an audio signal.
First thing that came to mind was _motorboating_ - parasitic feedback, used to be a common issue in early transistor (and valve) amps.
Yes. I think that was due to inadequate capacitors across the DC suply. Something loud and short could drag the voltage down and it would reduce the maximum audio output amplitude.
Yes, soon as I heard I said same. You should see it on a scope but motorboating capacitor is the term. Only us older guys would have felt the pain and always on audio amplifiers. If it happens in an if or rf stage of a wields, then that’s also a challenge. Especially on a superhet Circuit.
@@patrickjmorgan Older guys, what do you mean older - I'm only 72 :-)
!00% agree with the motor-boating description. I believe the cap was either poorly connected at one end of its own connection pad. Hence the heat making things expand and work. Or cracked and heating it made it temporarily connect. The reason I’m sure it was this is the fault stayed when you completely removed it.
Absolutely this is what we found
Persistence paid off, nice fix Vince!
Thank you John
oh my gosh!! i used to watch your videos back in 2017 can’t believe how long ago that was nice to see you :-)
Interesting issue, even more interesting diagnosing :P Glad you got it fixed.
Thanks Karthor 👍
Another awesome video!! Thanks for doing what you do. Always a joy.
You prob won't see this Vince, but also in the early days of PS3 YLOD (Yellow Light Of Death) repair strategies, heating up the tantulum capacitors also had the effect of temporarily fixing the YLOD fault. This led to theories that the heat was reballing the chip, when really it was just the caps that were the issue. Great vid as always :)
it actually turned out to be something like a mere 3% of the diagnosed cases. turns out its mostly the solder between the gpu die and the interposer, or the interposer and the main substrate pcb failing due to the heat cycles screwing up the connection. none of which is fixable, without replacing the gpu chip itself.
@@kenabi ah thanks for the info :) I've got an old PS3 YLOD and some replacement caps, so I'll give it a shot, but steel myself fir the chance it may still not work! Fingers crossed...
@@johnparker007 The channel "RIP Felix" (@ripfelix3020) has a view on it from around year ago. I don't know if there's been another or more info. _"A PS3 Story: The Yellow Light Of Death"_
@@johnparker007ripfelix on youtube has made a great analysis video about the ps3 ylod and indeed its not the caps but the gpu underfill that due to thermal expansion makes it so that the gpu die gets discconected/moved from the substrate and that caused the ylod. I can link the video if you want
That RC combo on the output is called a Zobel network and it's there to add a load to the output at higher frequencies (where the speaker impedance starts going up). Problems with the Zobel can upset the feedback circuit causing oscillations.
How to fault find ? Replace the speaker with a 8 ohm dummy load and check the amp output on the scope. It would have been ok (because the resistor has no inductance and thus has flat frequency response). That would have been a clue pointing to the Zobel.
Hindsight makes it easy to say do this or that. We want to locate the fault not because its economical, but for knowledge and experience improving, honing our skills. My lesson from this excellent repair is next time, disconnect one speaker in the initial observations, could have pinpointed it to one of the stereo amps. Great work.
It has been a minute since I have watched one of your videos, honestly didn't see you were posting as much as you are. The quality has gone up quite a bit, fantastic job! Always nice seeing a channel I enjoy growing. Keep it up man.
Vince is bringing home the bacon!
very well done vince like you my first step after checing voltages would be to change the chip.
after that i would of used freezer spray to try and pinpoint the fault .
Nice Job Vince, tenacity paid off. I thought a capacitor or something on the power input side and would probably have been the cause, but I also suspected the chip too. You could possibly have used the scope to find the area where the noise was coming from. Great Job as always👍
Nice catch ! I work on a lot of audio and I don't know how you found it without at scope !!! With faults on audio you usually have one channel thats ok so its a simple mater of following a signal around. I would have stuck a known signal, usually 1Khz at the input and taken it from there. That cap was almost certainly a filter so upping the capacitance won't hurt but the 10nF is a Tenth! of what it should be. The speed of the clicks is governed by an RC network thats a cap and res combination and with the circuit diagram you could work out the clicks but who cares. Essentially you got a bit lucky ! and in no way am I dissing you but thats your determination. Without a scope I would have binned it and chalked it up with the rest...cheers
You asked how else could that be found?... A tool used in radio repair called a "Signal Tracer". It is used to find noisy or open signals. One probes an audio source from input to output to find noisy transistors, tubes (you call 'em valves), and faulty capacitors. That capacitor you replaced would be referred to as a "Coupling Capacitor" where it would allow an AC signal of a specific frequency to pass through. What was happening is that in that circuit was being amplified. Any amplifier will amplify everything... in that case likely some type of audio mixer... and the pulse of the mixer was not being filtered or blocked by the faulty capacitor. Thank you very much for your "Fix It" videos. I also enjoy fixing whatever I can. Greetings from Oregon, USA.
Oh yes. Building your own signal tracer was a rite of passage in the 80's. Great piece of kit as simple as using an oscillator injector and an amplifier and earpiece.
The reason that your record player was making that popping noise, in my opinion, was that the faulty/ wrong value capacitor had turned one channel of your audio amp into a blocking oscillator! Full marks for perseverance, though!
Maybe it is a cracked capacitor? Great fix!
I will love to find a great repair man like you where i live, i want to repair a Arcadia 2001 console i buy some years ago, but there is not fix videos of this console and i don't know where to start looking how to fix it, also, the components will probably be imposible to find in my country anyway. Great video.
Hi Vince, I've heard similar faults in audio equipment and there too was the fault caused by the capacitors. Next time you deal with faults having similar behavior, you will know - A capaciThor is at fault. You just have to find which one. Other than that, good job mate!
I would always use freeze spray before using the hot air. I fixed hundreds of faults that way in the '90s without even referring to the service manual. Always aimed at the semiconductors in those days.
We didn't have SMD MLC capacitors back then so it's interesting that they are also prone to thermal faults. Having said that it is probably more likely someone at the P&P factory replaced a mislaid 100nF with a 10nF at the board rework station.
Well done Vince! You did it!
My money was on a capacitor from the beginning, just from the sound and the fact that it changed when the volume (voltage of the pot) changed.
My layman explanation would be that the smaller capacitor wasn't able to absorb the fluctuations to filter out the noise, kind of like if you were using a really small funnel to fill a bottle, from an erratic tap, and you get water splashing out of the funnel when the tap spurts, like when there's air in the line.
I'm not an expert by any means, and I might be totally off the mark, but this is what my brain thinks!
the capacitor(s) must be used as a noise filter, so if one capacitor is only 10ohm then more noise from e.g. the motor can get through, and with a 100ohm it filters out more noise. yes there are many ways to make a noise filter today😅, I hadn't thought in that direction either, but you can just see how such a small capacitor can wreak so much havoc.😂thanks for teaching us about such a problem and where that problem can be on the circuit board🥰
cheramic capacitor easily gets micro cracks, especially when the pcb bends a little. you measure short circuit or open. very common problem in mobile telephones and laptops
Yet another great fix - I am always amazed by your persistence and ingenuity.
I guess the "swearing" moments are cut out with edits. Surely there must be an odd moment where you just think !!!!!!!. Come on Vince you are human (aren't you, not AI!!!).😉😉
Indeed strange problem. In the 80's there was probably much more testing and quality control was better, so very very few faulty items ended up in consumer hands. Now it seems there's a lot of faulty items, and QC is a joke these days.
Roland Rat is the only Hand puppet I’d happily stick my foot up, thanks for playing side B (instrumental) 😅
Generally, I was taught you MUST remove a capacitor in order to get the correct value. You pretty much confirmed that. I admire your determination to find the fault. Using the heat probably expanded the micro- crack in the cap. By pushing on it with your finger, you were manually flexing the ceramic. There are more advanced ways of finding a faulty capacitor, but hey, it worked. Sorry you had to spend hours figuring it out, but that's always the process of learning anyway. The next time around will take minutes.
Wow, what a great piece of detective work. Sherlock Ohms! Now, what was popping that the cap had to filter it out? That's what I'm wondering.
Different ceramics used will have a different response to temperature, some types (NP0, C0G) are designed to remain fairly constant and are generally up to about 100pF or so, although they can be had up to 100nF or more, depending. These are found mainly in timing circuits or the loading capacitors adjacent to quartz crystal units.
Another group (X7R, X5R, etc) are usually used for decoupling, generally around 100nF to 10µf, they're not as stable, but still usable in non critical applications. Then there's the ghastly Y5V and Z5U grades which have tolerances from +80 to -50% (or something along those lines) depending on how you look at them. These change with both time and temperature, but have a higher dielectric constant, meaning for higher capacitance value in less space.
Gotta love tradeoffs.
I think that specific capacitor is just plain bad or has somehow been internally damaged or otherwise defective, but working with pick and place machines, sometimes they'll mispick a component, which ends up at a funny angle in the tape, then gets flung out when the feeder advances. Sometimes they'll end up laying on the board, falling down inside the machine someplace, or landing on top of an identical-appearing (to machine vision) component in an adjacent feeder, then hoovered up and placed someplace on the board where another part was intended to go.
Sometimes the carrier tape that the parts come in is just plain garbage *cough*Yageo*, and parts will end up sticking to the cover tape or getting popped up out of the carrier tape by an irregular bottom layer underneath, causing all sorts of mayhem.
If you have enough familiarity with the boards you're working on, the specific parts you're using and the intricacies of what they look like, and are used to examining these things up close for several years, you'll notice it almost immediately if something isn't right.
Those tiny ceramic caps are a PITA in electronics longevity. We used to have a plasma TV which stopped turning on unless you let it rest for a few hours, which is a telltale sign of caps usually. Got quoted almost the price of a new telly at the service. But swapping two of those specks of dust on each of the sustain voltage generator sub-boards got it back to life! Until I tried to repair a broken HDMI port and fried the CPU some 10 years later :-)
Somehow I knew within the first 1:10 that it was to do with the capacitor on the audio side - What a G I am!
Those capacitors are likely decoupeling capacitors to remove dc interference from the dc turn table motor and seperate the ac audio signal from it.
Well done Vince!!! Perseverance pays off!!! ❤
Thanks for the video.
I would try and trace the noise back from the speaker to the source using a cheap signal tracer, like the velleman, k7000.
It works wonders for me.
Hi Vince, I don’t have much to contribute in terms of technical help but I think the returns label says Vinyl (misspelt as Vinyle) Scraping. Fairly new viewer here but catching up rather quickly. Keep up the great work!
It depends on what the circuit is and where in the circuit it is. Without a circuit diagram, we can only speculate. Reverse engineering the amp circuit would show what the cap's application is. the stuff we learn from repairs of this stuff is far more rewarding that doing crossword puzzles :-)))
You could fault find this with a scope by measuring the signal of the input of the amplifier and then gradually backwards until the signal from the needled. You could find after which component the noise appears.
Ok in case these are decoupling capacitors you could see that one supply voltage has much more noise.
Well Done for find out the fault
Great fix 👍 now take it to the tip
loved the b roll of the sleeping haha cool fix
Yes. That's what I saw as soon as It was shown. I thought it was pretty obvious? Still I doubt if I could give it!
Ohhh Vince and you came and you gave without takingggg :)
DC decoupling caps probably. The scope would have shown the spikes that you were hearing most likely on the DC rails. With high gain circuits like this I would likely have paralleled up any capacitors on the input side to test the effects. Sometimes even the parallel capacitance of the scope probe will affect the circuit, depending on frequency. Many types of caps are affected by temperature, as you discovered. Still a good fix though, albeit a substitution marathon!
Vince, I think the fault stated on label was supposed to read “Needle Scraping”. I also saw another commenter interpret it as “vinyl scraping”. Both are possible interpretations.
Prolly signal probe would be way better than the oscilloscope, you could check the signal as it goes from the cartridge and hear where the popping starts. Look for some schematics as they are easy to make. I'm long overdue for making one for myself.
that kind of noise ive found to be capacitor faults so i would have been looking for something wrong in that regard right away, the fact that it was only one one side would have had me looking for a paired set with one being different
as for the why, i dont actually know for sure but i suspect it has to do with the smaller cap being overcharged, iirc resistance goes up as the the charge goes up so an overcharged cap would behave close to an open hence why removing it made the click worse. my guess is that the signal is supposed to go through at a set rate but it cant if the capacitor is saturated and heat increases conductivity which temporarily resolved the issue
the part im having a hard time sorting out is why the clicking, i would have expected no sound at all on that channel instead or being choppy/quiet
worth noting that i would not have found this issue, i dont touch smd components and always assume they are okay, i dont have steady enough hands to do that kind of repair so if thats the issue then its junk and i cant do anything about it
An idea that I just had: Maybe using your oscilloscope you could've traced back the audio signal backwards from the output until you find a place without the pops.
Yes, maybe they would have shown up on the scope. Thank you
Such oscillations show up trough the entire loop, that's the nature of feedback. There is no "begin" to find.
Would it go back all the way to the needle ? @@unimportant5122
@@Mymatevince Instead of a scope you could use an old earphone you don't care damaging if it lands on the wrong spot in the circuit. That however would also need you to have something playing on the turntable to have a reference signal...
Motor boating is caused by the presence of the output signal on the DC supply line. This couples to the input causing the amplifier to become unstable and oscillate. The shunt capacitor acts as a filter, combined with a series element, to supress this unwanted feedback.
I think it says Vinyl Scraping - The I ,N and A match in the word scraping. Whoever wrote that did not know how to spell Vinyl.. so they did it phonetically... Vin-ALE :P
Saw "Bush" and was frightened right from the video start.. 🤣
When you add heat it expands the capacitor, in turn increases the capacitance by increasing the space between the plates. (Lessens the chance of shorting)
Class D style amplifiers are make sound by PWM, so they are very noisy and need a filter network to clean the signal to produce sound rather than erratic noise.
When in doubt about values, check the spec sheet, in most cases the circuit will be a near copy of what is in the sample circuit.
I would have used an oscilloscope to first test the input and output of the audio amplifier IC, then you would know which side of the circuitry was at fault, secondly low-frequency popping sounds are always faulty capacitors which smooth out voltage spikes which cause audio pops
I was going to suggest these were smoothing caps to eliminate ripple.
Nice work on the fix nice.
That was a faulty filter cap. You can hear it in how when you changed changed power supplies the the oscillation changed. I would have troubleshooted with an oscilloscope going from the speakers to the board to check the components as I progress backwards from the symptom.
Hello Vince, thank you for a not only entertaining channel but a very informative one as well. I used to be a TV engineer years ago and I take a particular interest in your repairs. In my day we didn't have IR cameras or even hot air devices, in this particular programme I was surprised you added more heat to diagnose a fault that was caused by or created heat. By experience this can sometimes lead to a positive result but can also exacerbate or mislead. In the past we widely used "freeze sprays" to find these particular rogue components, in fact as soon as I started watching this one I muttered to myself that it was a capacitor fault. Are freeze sprays still available do you know? Another tool I used was a signal probe. We'd make one up ourselves, a small oscillator set to either an audio or RF frequency and touch it to different parts of the circuit to assess the output, either audio or to an oscilloscope.
Used freezer spray up to three years ago when I was forcibly retired (they call it redundancy). Great stuff for finding intermittent open circuits.
aaah.that's motor boating.low frequency oscillation caused by poor DC decoupling on the power rails.usually solved by a 100uF and 100nF capacitor in parallel and then series with a 10 ohm resistor across the power rail as close to the IC pins as possible.
the cap is part of a zobel filter it's purpose is to stop amp oscillating with long speaker leads with an Inductor at the end I'd speaker coil.
cap is in series with resistor typically 4.7 to 10 R
There seems to be a good percentage of Bush faults , i remember must be 50 years afo my sister had a Bush music center and every time a taxi came past you could hear them on their radio even if it was playing a record 🤣
Zobel network,R/C combination at the output of each amp,maintains a constant load impedance over the frequency range.
We need to send Vince vinyl with Daniel O'Donnell music for testing 🤣
Yeah, MLC capacitors like that are known to be relatively fragile, they can fracture internally from many different causes (thermal stress, physical damage or something else). Your capacitance measure for it is all over the place which is the signature of cracked MLCs so I don't believe the pick-n-place used the wrong capacitor. This is likely also what caused the crackling, it was switching between various states with different capacitance and quite possibly either "short" (resistor) or "open"!
I agree that it was very likely faulty from the factory, but I think the reason was either the MLC being pre-cracked, the pick-n-place machine cracking it or thermal stress. A proper QA would pick up the error but given the likely price-bracket for this item I expect there was little or no QA. Using heated air like you did can also cause MLCs to crack like thus but it's rare and the error was clearly pre-existing so we know that wasn't the case here.
Well done Vince, you’re like me a dog with a bone lol… Don’t heat up components with a soldering iron on mains power supplies it tends to blow the electric lol, I touched the top of an electrolytic capacitor that was on the hot side it let off a massive bang and a flash and the electric went lol 😂
Strange that it didn’t do it when you changed the chip, but then maybe the cap had heated up when the chip was changed 😊
To keep track of small components just use scotch tape. And you can write the values or whatever on the tape. My problem is that my bench will tend to accumulate various pieces of tape that I occasionally throw away.
We used to use freezer spray to identify faulty components
in circuit capacitance should read the same on both channels would be a good way to find it. The clicking only got fast when you took the one cap off the good side. Maybe they both were clicking then and out of phase so it just sounded faster. When you removed the bad cap it still clicked.
'Vungle Sarapin' - That's a band name right there... 😁👍
Technicians use to call this sound “motor boating” it is usually a filter capacitor going bad.
It would be difficult to fault find without a spare working unit but not impossible. As the problem was only with one channel you can at least swap components between left and right channels until the fault swaps to the other channel. I would Google for the datasheets of each IC and work out what pins did what and by process of elimination work out the audio path and swap components on left and right channels until the fault was found or I gave up because it's not really worth the effort. If you stick at it you can always find the fault (not always fix it though), it's just a matter of time and determination. On the point about the faulty capacitor, it could be a wrongly picked part, but most likely is a failed component. Ceramic capacitors are constructed in layers, these layers crack with stress and the part changed value, becomes leaky (electronically) or shorted. It could have failed in actual manufacture or during storage or at the actual time of assembly (pick and place) or at any time after that. Also how the capacitor read on your tester doesn't necessarily mean that is it's actual value when in use and voltage or signal is applied to it. At that point it could be open circuit. Testing a component can really only give you an indication of failure or loss of performance. Try fitting a 10nf capacitor and see if it makes that noise again- that's the real way to find out - by experimentation. If it makes that noise you know it needs to be 100nf or at least greater than 10nf, if it doesn't make that noise you can assume the original capacitor was open circuit and the reading on your meter was false.
Thanks Radio Ged👍
Capacitors can act weird when heated up(chabging capacitance/esr/resistance), and surely when its faulty! The capacitor was probably filtering things or it was going to the input of the amp/opamp
Anyone else remember that scene in Dumb and Dumber where he asks if you want to hear the most annoying sound in the world?
Vince does the chip have a number? I would try to figure out what it does. Analog electronics isn't all that bad and often of an opamp is involved it can explain what the capacitor is doing. My guess would be that it was in a feedback circuit of an opamp and perhaps not filtering significant signal out thus overloading the amplifier. That could explain why it was heating up. The feedback circuit controls gain, otherwise it can saturate the output.
The down side to testing those capacitors with those little battery type readers is that if your not testing them close to their rated voltage, many times they'll read as good when they are not. I use a heathkit IT-11 that I refurbished.
PMSL. This is trolling for sure. I know you must be a fan of Mr Carlsons Lab.
Low voltage MLCC's are definitely prone to different voltage and frequency curves and so the datasheet has to be referred to.
I would suggest something like a DER-EE DE5000 is more appropriate than something designed for 500V caps from the 1940's.
100mf cap would also be in phase with the 9V power input if it is just rectified ac. 10mf would not phase out all the noise.
There was a time when you would have tested all the caps first. Measuring them in circuit might not give you an accurate reading but you can still compare the left channel to the right one. That might have shown the fault. MLC capacitors like that are very fragile. Just the heat from soldering them can sometimes cause them to crack. They often fail short circuit, but not always. Sometimes they fail open and sometimes they drastically change the capacitance value.
Ah, the wonders of tiny ceramic capacitors. Although they may have fitted a wrongun during manufacture, they are easily damaged by spikes, vibration and heat (not that pick-and-place and reflow would ever introduce such anomalies). Fyi, I would ask for your money back on that tattoo. You need an NF (gold plated) capacitor book.
first thing I said when i heard it at the beginning of the video,, was faulty capacitor.. having fixed something with a similar fault years ago
Good work Sherlock... 🙂
😂 Thank you Mike!
Great fix.
Cheers Paul
Hmmm, I see busted knuckles. Must be a good Rolls Royce video coming soon!!!
The popping was clearly a cap, and since it was happening at the speaker you backtrace from there. Unplug one speaker and then the other, and within a minute or two you will find the culprit.
for £30 retail it's amazing it does anything at all. Even it wasn't faulty the best place for it is the bin. The cartridge/pick-up/stylus/needle is going to ruin an record it touches.
Vince, that is not a record player, I wouldn’t dare put my precious vinyl on that junk, its best used as a pedestal for the missus to stand on when her heels are just not high enough, 😂😂
😂😂😂
this freaking sound is now burnt into my very soul.
Some stuff being diagnosed can be a hair pulling event , I've had a few Cobra 29 GTL in the early 90's the 10.240 Mhz crystal legs were eaten away by the board glue ....
Missed clue was the repetition of the noise. Faster when TT rotation increases. Capacitors are probably in the filter for the servo motor pulsing. IC nearlby would be a servo driver chip?
Could they have meant 'Vinyl Scraping'? (sorry just read that someone else got it already lol). Good job on the repair, lucky you had a spare to compare.
Loving the Roland Rat LP 😅
Capacitors are often used to improve the quality of sound, image or signal. A computer can for example start without a capacitor. In troubleshooting. You can try removing a capacitor temporarily. But in this case it whould not tell. Maybe with a better PSU. Schematic and measuring not possible either. It should be possible to figure out what kind of capacitors is necessary depening on other components.
ok here's my best I have fact checked this as well as i can but please some one tell me I'm wrong if I am.
1.Temperature changes can alter a dielectric material’s properties, such as its permittivity and dielectric strength. Permittivity, which is the ability of the dielectric to store an electric charge, varies with temperature for different materials. For instance, some materials exhibit a decrease in permittivity as the temperature increases, resulting in reduced capacitance. Conversely, other materials exhibit an increase in permittivity with increasing temperature, causing an increase in capacitance.
2. I would imagine a scope would pick this up with no issues at all as its causing noise in the system with the correct settings you would see the audible pops on the scope using it to trace the issue is another thing altogether but you could trace if the noise was occurring before or after the amp but seeing as the volume nob effected it its more than likely the latte.
3. As for the difference in capacitance if these caps are used for noise reduction after or before the amp the tolerances etc matter way more than other uses of capacitors.
Personally i would think the cap was faulty and the rating is a result of that rather than it just being higher rated but im unsure of this can can't find a good answer on line.
That player would be great in a club, gives a great beat 😂
22:34 - I would use simple Kelvin probe/4Wire (Made of LM317 and USB power) to go across SMD capacitors. Then chart them from good board and check them on bad board. I believe it would take 30 minutes and you have written data for next repair when you dont have known good board.
Imagine that on a big board full of them... Hang on that's got me thinking the projector sorry VINCE
This is a situation where you have to becareful not to assume. The LIR doesn't indicate a faulty chip, just a warm chip. High voltage can cause a chip to get hot, but the thing the digital meter won't show you is the ripple on the voltage, which can also cause those chips to get hot. The digital meter isn't sensitive enough to show the ripple on a DC voltage. Those SMD caps, especially cheap ones, can be problematic and they are usually used as decoupling caps in this type of circuit, which acts to stabilise the voltage to the chips.
The capacitance is not an issue with decoupling caps. They can be off 20% and still do the job. I very much doubt the wrong capacitor was picked up by the pick and place machine. It is actually a faulty capacitor. That's why the hot air affected it.
If you have an oscilloscope you would see where the noise is coming from. You can also use analogue metres that can respond a lot quicker and allow the fault to be seen.
Ultimately, I think that capacitor being faulty was causing some kind of oscilation in the circuit. That would explain the variance depending on volume level. To do further testing, you'd get a spec sheet for the amplifier chip, which often will tell you values of components for standard usage. Often the manufacturers of the chips have a basic schematic of their recommended circuit for use.
Given the price of those record players, a lot of places would not bother fixing them because half an hour of time on it is the price of going out and buying one new.