I have a repair shop. Just answered another email from a new customer telling me that he thinks his "amplifier just needs the capacitors replaced".
While, yes, sometimes indeed the caps need a swap, it's silly how the general public seems to believe that every audio issue in their world is caused by the need for a "caps swap." Where did this begin? How can we stop this?
conditions which people have tried to convince me can be repaired with a caps swap:
"my amplifier won't turn on" - caps swap
"one channel is really distorted" - caps swap
"smoke came out and then it sounded really bad" - caps swap
"I heard a pop and now there is no bass" - caps swap
"I found this speaker outside and thought it might still be good" - caps swap
Stay tuned for part II: "just needs a little solder"
While, yes, sometimes indeed the caps need a swap, it's silly how the general public seems to believe that every audio issue in their world is caused by the need for a "caps swap." Where did this begin? How can we stop this?
conditions which people have tried to convince me can be repaired with a caps swap:
"my amplifier won't turn on" - caps swap
"one channel is really distorted" - caps swap
"smoke came out and then it sounded really bad" - caps swap
"I heard a pop and now there is no bass" - caps swap
"I found this speaker outside and thought it might still be good" - caps swap
Stay tuned for part II: "just needs a little solder"
There's no excuse for not testing the unit before working on it, to see if there is actually a problem and what the problem actually is.
I've seen amplifiers that worked perfectly fine but didn't "sound" the way they used to. Replacing the electrolytics restored the performance. BUT there wasn't anything really wrong with them, except they were 40 years old with all original parts. Big electrolytics can easily lose half or more of their capacity after 40 years of service. Plus weak or defective electrolytics in the power supply can stress power transformers.
I've seen amplifiers that worked perfectly fine but didn't "sound" the way they used to. Replacing the electrolytics restored the performance. BUT there wasn't anything really wrong with them, except they were 40 years old with all original parts. Big electrolytics can easily lose half or more of their capacity after 40 years of service. Plus weak or defective electrolytics in the power supply can stress power transformers.
Better get used to it. Given that the "general public" are pretty ignorant when it comes to electronics (and most other things), this is really no surprise.
jeff
It's interesting when amateurs lecture me on capacitors. Kids that are into mobile stereo know more about capacitors than trained engineers do.
Do what every scammer does..swap the caps and take the money.If you don't do it , they'll pay three times more somebody else to do it.There's no cure for this illness...
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If you only have a hammer, everything looks like a nail.
In my country the minimum wage was about 250 euros back whenone of my best friends asked me to recap a Teac amp.Listening to it i recognized it was sounding very well and advised him to let it live.My usual price for a fix for him was about 15 euros. Then he paid 150 euros plus the capacitors price to a scammer to recap the whole thing...He never paid me more than 20 euros for anything...so don't be stupid's friend.Just take their money or someone else will.I stopped helping that person since...he couldn't even hear 12kHz...but he develloped into a huge audiophile with a great body of knowledge....
Being an audiophile isn't about knowledge. It's about a state of mind, an image.
And since I attended engineering school, I am unfortunately bound by the laws of physics. What a bummer! What I couldn't do if only I didn't know so much.
I'm not sure on 40 years lifetime, especially with some amps being a burning oven from the 1990s where temps reduce lifetime of the already low 3000 hour caps.
I think part of it is that it's easy to understand the concept of replacing capacitors. Or rolling tubes/opamps.
Typically these persons have no technical knowledge.
It's the equivalent of 'if you only know how to use a hammer, all problems look like nails'.
Edit - I see Rayma beat me to it ...
Jan
If the customer knows what he wants then why just not deliver the service... 😉
Generally speaking - if equipment is e.g. 30 years old then wipe-replacement of all electrolytic capacitors (for current and good ones) - except perhaps the "big main ones" - would provide assurance to the owner that the device will not go into oscillation or start generating hum at least for the next decade.
Having measured such capacitors as a hobby for some tens of old devices I recall very few of these (devices) without a degraded capacitor.
So for decades old equipment I would consider capacitor replacement as a standard routine before any additional fault searching - a bit like a surgeon washing their hands before surgery.
When they explicitly ask for capacitor to be replaced, I replace at least the few that are stressed more than the others, such as the nearest to linear voltage regulators. After more than 20 years they may still be within tolerances and perhaps I would not have replaced them, but they are still degraded, and sometimes actually defective. Then I will repair the actual fault, if any. Leaking electrolytic capacitor failures are rare lately, but I rarely fix analog audio products so I don't have a complete picture. I mainly repair digital boards, and now many faults are related to shorted SMT MLCC bypass capacitors.
Degradation that I am referring to in my previous post ranges in loss of capacitance from 30 to 100% and ESR increase to e.g. 10...70 ohms. When you find one such capacitor in an old (and worthy restoring) device then the safest route is to replace them all without spending time on thinking twice. Components do not cost much and wipe-replacing is a fast soldering job. At least the owner will not lose much sleep on wondering how many bad caps were left "in the box".
As an example one power amplifier of quite well known manufacturer - being of ca 15 years of age - had used some Chinese capacitors 50% of which were practically "dead" (I measured them all after soldering them out) and the remaining ones had severe loss in capacity. Had to replace them all - so it is not just a case of very old equipment.
A combination of factors, none legit.
In no particular order:
* users are worried about their stuff and want to restore/improve it ... but have no clue.
* "Audiophile" Magazine/Page editors simply have to write "something" even if just to fill space, even if poor Science or plain nonsense; warning about Capacitor Doom is as good as anything else.
* since repair fell in disfavour, stuff gets discarded, repair shops have dead days ... needlessly swapping caps helps using them and bringing in some action/profit; so they will warmly accept User demands.
* in those cases where user "has a soldering iron and knows how to use it" ... but not much else, plain capacitor swapping, either same for same or by an "improved" version brings ego massaging "builder´s pride" in.
All of these comments are correct.
Because the electrolytic caps are 30-50yr old on the components currently in vogue, it is, in fact, quite likely that some of the caps are aged to the point of degradation. So replacing can be of (possibly major) benefit. And that bit of truth has become magnified to where we are today.
Because the electrolytic caps are 30-50yr old on the components currently in vogue, it is, in fact, quite likely that some of the caps are aged to the point of degradation. So replacing can be of (possibly major) benefit. And that bit of truth has become magnified to where we are today.
Well if you ever heard about the " bad orange caps replacement" in Nakamichi cassette decks you know how far this ilness go.It happened that for a short while Nakamichi assembled less than 100 cassette players with a batch of mylar caps that for some weird reason got faulty after 20 years of use...Since A.N.T advertised their replacement in some of the decks he serviced, every single self made "cassette deck guru" is replacing or at least advising the replacement of all the orange caps in any Nakamichi equipment he sees'em in...
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@hild
Before you get to part 2 of your story, I´ll sqeeze in another one of mine (probably your part 3 🤣 🤣 )
When it´s the pocket book speaking. Gave up counting how many times a person brought in a faulty product
with the comment: "It´s probably just a fuse". My usual response was: "If it´s just a fuse, why don´t you just replace it yourself??"
Further attempts to advice me on my job usually stopped right there 😉
Before you get to part 2 of your story, I´ll sqeeze in another one of mine (probably your part 3 🤣 🤣 )
When it´s the pocket book speaking. Gave up counting how many times a person brought in a faulty product
with the comment: "It´s probably just a fuse". My usual response was: "If it´s just a fuse, why don´t you just replace it yourself??"
Further attempts to advice me on my job usually stopped right there 😉
I should have also said that my shop works mainly on modern electronics. Every once in a while, we get an old classic piece, like a Marantz amp, which often does indeed need those big electros swapped. Any sort of high-heat situation receives extra attention wrt electros.
To be a bit more specific, the "capacitor issue" we see a lot involves speakers with the power amp on-board. You know the ones: most small-club PA speakers, pro-sumer (and a lot of pro) studio monitors. They almost always have one of those monolithic ICs driving the outputs. (those TDA parts, or similar.) The main thing we find is a blown output section (because of the IC overheating) which causes all sorts of fun catastrophic problems--which sometimes involves blown caps, but almost always other burned parts as well. And cooked voice coils.
And yes, as Boydk said, we get plenty of "I think the fuse just needs to be replaced". To which the response 99.999999% of the time is: "sure, the fuse is blown--and we need to (charge you money to) find out why."
But we do our best not to be too cynical over here: if a customer absolutely wants us to do it, and they are fine paying the labor fee, we'll do it. And believe me, we've seen some old synths come into the shop with tantalums in... places which shan't be mentioned. horrible places. Those get replaced immediately. But man, if a kid comes in with a KRK that won't turn on, it saves us a lot of time and trouble (read: money) if we just advise them to move on.
On the other hand: we do work on a particular brand of modern turntable which nearly unfailingly needs new filter caps. It's insane. Like, you don't even need to test. Just go ahead and swap em. It's like this company went to radio shack and said, "nah, these are too good". No one should buy their stuff. Just awful parts and careless design. We'll happily charge money for that repair.
new hot topic: quite often, we'll pull out old caps to find that they test better than some of the replacements. Like, an old, big electro with milli-ohms ESR (and dead-on C value) vs. a brand new one with 1-2 ohms of ESR and higher V loss. Swap or no swap?
To be a bit more specific, the "capacitor issue" we see a lot involves speakers with the power amp on-board. You know the ones: most small-club PA speakers, pro-sumer (and a lot of pro) studio monitors. They almost always have one of those monolithic ICs driving the outputs. (those TDA parts, or similar.) The main thing we find is a blown output section (because of the IC overheating) which causes all sorts of fun catastrophic problems--which sometimes involves blown caps, but almost always other burned parts as well. And cooked voice coils.
And yes, as Boydk said, we get plenty of "I think the fuse just needs to be replaced". To which the response 99.999999% of the time is: "sure, the fuse is blown--and we need to (charge you money to) find out why."
But we do our best not to be too cynical over here: if a customer absolutely wants us to do it, and they are fine paying the labor fee, we'll do it. And believe me, we've seen some old synths come into the shop with tantalums in... places which shan't be mentioned. horrible places. Those get replaced immediately. But man, if a kid comes in with a KRK that won't turn on, it saves us a lot of time and trouble (read: money) if we just advise them to move on.
On the other hand: we do work on a particular brand of modern turntable which nearly unfailingly needs new filter caps. It's insane. Like, you don't even need to test. Just go ahead and swap em. It's like this company went to radio shack and said, "nah, these are too good". No one should buy their stuff. Just awful parts and careless design. We'll happily charge money for that repair.
new hot topic: quite often, we'll pull out old caps to find that they test better than some of the replacements. Like, an old, big electro with milli-ohms ESR (and dead-on C value) vs. a brand new one with 1-2 ohms of ESR and higher V loss. Swap or no swap?