[sdiy] "Zerolytics"

Chromatest J. Pantsmaker chromatest at azburners.org
Tue May 5 15:24:23 CEST 2020


At work we have many high-end powered studio monitors.  They're getting up
there in age and they start to hum louder and louder.
Guess what fixes the problem?
New capacitors in the power supply.
Sure, not ALL of the capacitors are bad.  It's generally the two big ones,
but once it's pulled from the studio and torn down to replace one
capacitor, we just replace all of them in the PS.

On Tue, May 5, 2020 at 5:14 AM john slee <indigoid at oldcorollas.org> wrote:

> I have also been somewhat bemused by these comments, having worked with
> computers my entire career and survived the capacitor plague.
>
> Richard Devine is on record saying that he simply leaves all his modular
> synths turned on all the time. Perhaps...
>
> * his synth enclosures are well ventilated
> * he has amazing climate control
> * all the electrolytic caps in all his modular gear are 105C / 12000 hour
> rated
> * unicorns are casually shitting the most incredible rainbows on his front
> lawn
>
> Even then... why would Panasonic et al put hour ratings on their products
> if they were immortal?
>
> John
>
> On Tue, 5 May 2020 at 21:11, Steve Lenham <steve at bendentech.co.uk> wrote:
>
>> On 05/05/2020 11:31, Gordonjcp wrote:
>> > You'll never need to "recap" a power supply.  Ever.  Unless you've done
>> something crazy and actually damaged it, of course.
>>
>> Sorry, but you post this over and over and it just isn't true. Saying
>> that you never need to recap a power supply is every bit as extreme -
>> and mistaken - as saying that you should always do it.
>>
>> Two real-world examples:
>>
>> 1. I worked on some jolly expensive Apogee converter units that wouldn't
>> turn on. They used off-the-shelf switch-mode power supply modules and
>> didn't have a proper hard power switch, only a standby mode. This meant
>> that the SMPS was running all the time that power was connected; the
>> output reservoir caps in an SMPS work fairly hard and these were dead.
>> It's a situation that is increasingly common and will cause the
>> premature demise of a lot of gear, so Quantec IMO have the right idea.
>>
>> The best electrolytic caps have a rated lifetime of around 12000 hours.
>> Yes, this is at their max rated temperature and lifetime doubles for
>> every 10 degrees below that temp, but there are 8760 hours in a year so
>> you cannot rely on them for too many years if in constant use.
>>
>> I am told that the same problem afflicts the power supplies in Mac Pro
>> workstations, with computers costing a five-figure sum being put out of
>> action by a handful of worn-out electrolytic caps.
>>
>> 2. I work a lot on vintage Lexicon effects and they use late 70s/early
>> 80s tantalum caps and poor quality electrolytics. Same goes for e.g.
>> Prophet 5s. The tants are prone to spontaneously failing short-circuit -
>> not all of them, and not after any particular length of time, but
>> statistically it is quite common. Presumably in your world you would
>> wait for that to happen, then find the one bad cap and replace it - and
>> repair all the other damage it might have done. But a lot of people -
>> those that can't do repairs themselves, or are already having work done
>> on their gear, or just need their kit to keep working because they rely
>> on it - prefer to eliminate the possibility of such a failure happening
>> any time soon by fitting better quality modern caps. It is a question of
>> risk management.
>>
>> I could go on. I accept that good-quality electrolytics seeing moderate
>> 100Hz ripple in a well-ventilated piece of equipment can go on for a
>> very long time. But those conditions arise in a diminishing number of
>> cases.
>>
>> Cheers,
>>
>> Steve L.
>> Benden Sound Technology
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