No. Let’s dig into this.

I’ll cut to the chase: people don’t know what they don’t know, and we are all affected by this. As long as expert sources of information and professionals are sought when needed, this generally isn’t a problem, but they often aren’t, and that is a problem. With that in mind, I’m going to help clarify this topic.

Before we proceed, note that DIY electronic equipment repair attempts significantly increase:

1. The risk of equipment damage
2. The risk of the introduction of new faults
3. The risk of personal harm through electrocution

Each of these outcomes is bad, so stay safe, and if in doubt, take your equipment to a professional. I don’t need the work. I say this because I am deeply invested in keeping beautiful equipment alive and well.

Dunning-Kruger

The Dunning-Kruger effect describes people overestimating their understanding of topics they know little about. The problem is real, leading to people treating cancer with fruit juice, launching themselves in rockets, denying the moon landings and visiting the Titanic in home-made submersibles.

Dunning-Kruger has also led to an explosion of ‘recappers’ and poorly skilled ‘repairers’, and a ton of damaged and destroyed hi-fi equipment. It’s silly and wasteful, and I’ll call this stuff out where necessary.

Know this: One cannot know much about anything after a few minutes of reading, especially when your sources are others affected by Dunning-Kruger! Again, if in doubt, seek the advice of a trusted specialist.

Example

Capacitors are a poorly understood topic, and a reader’s comment on an article I wrote about the wonderful Kenwood KD-500 turntable prompted me to write this FAQ. Mark wrote:

A simple fix can be changing any electrolytic caps.. Always good to remove then [sic] and check there [sic] capacitance. 10% below should be changed.

Mark

Grammar aside, the danger (Dunning-Kruger) lies in what is not understood and therefore not said. Mark has likely not repaired, owned or even used a KD-500, but he’s offering incorrect ‘advice’ which will not only not help the original enquirer fix his turntable, but will likely lead to him damaging it.

Capacitors can be removed and tested for capacitance, but Mark ignored ESR and leakage, which are more important. The bigger issue is that capacitors are almost never responsible for speed issues here, so the fundamental advice is wrong.

The biggest issue is the unawareness of the damage that DIYers often cause. DIYers typically lack suitable test equipment, rework tools, knowledge and skill needed to effectively take on this sort of work and very often damage or even destroy equipment. This isn’t a judgement BTW, it’s a simple statement of fact.

My reply:

Thanks for your comment, Mark. I appreciate trying to assist others, but given that your comment highlights general misinformation regarding technical electronics repair and only encourages capacitor replacement rather than finding and fixing the issues, it’s helpful if I explain why.

Capacitors are much maligned and poorly understood. Capacitors should be checked, but rarely cause speed issues with these decks. New caps are typically specified to be within +/- 20% of rated capacitance, like these excellent Panasonic parts: https://industrial.panasonic.com/cdbs/www-data/pdf/RDF0000/ABA0000C1209.pdf.

A reading within +/- 20% is within new part specs and measurement error. Replacing capacitors that measure within 10% of spec is not only a waste of time and money, but it will not fix anything unless those parts also have a measurably very high ESR.

Most end-users also don’t have the test equipment needed to make these measurements accurately, nor the experience to interpret the results and therefore should not remove or change parts they cannot properly measure and assess.

Liquid Mike

Facts (Useful)

I’ve provided a few facts here to help readers, from a specialist’s perspective, as a science educator with an honours degree in science, FWIW. The internet is an echo chamber for misinformation. Public forums are largely to blame. Our advisory service and this entire website proudly combat this problem, and I’ll tell you this for free: there ain’t many technicians with honours degrees in science and 15 years experience teaching it 🙂

Are capacitors important? Sure. Should all capacitors measuring “10% below” be replaced? No. Did you know that brand-new capacitors typically test low for C, often more than 10% low? There’s nothing wrong with them; they need to reform. Did you know the average cheap multimeter cannot properly test for capacitance, ESR or leakage?

Capacitors can fail and must be replaced when they do. They can also be replaced to significantly improve performance, depending on their role in a circuit. However, a 10% variance from the rated spec does not constitute failure and is within the margin of measurement error of the test gear most owners will have access to.

Summary

All too often, people bin good parts and replace them with inferior parts, trying to solve problems not caused by those parts. There is so much nonsense advice offered about replacing every capacitor after a certain age, but I can assure readers that no truly informed specialist would ever recommend this.

Anyone doing so knows too little to be helpful but enough to be dangerous, and is probably selling parts. One self-described ‘technician’ sells kits on eBay, no surprises here. No self-respecting technician sells, uses or recommends kits.

ESR is a more important parameter than C in terms of capacitor health. Proper lab-grade test and measurement equipment is needed to effectively test capacitor parameters; cheap multimeters cannot do it, and most people do not own expensive test and measurement equipment.

Replacing parts often causes circuit board damage and introduces new faults when done by inexperienced folks with poor rework skills and tools. The best way to save and rejuventate equipment is to have an expert do it, someone with hopefully a decade or three of best practice behind them.