Re: [tlug] "But What's the Precise Technical Reason?"

["Lyle (Hiroshi) Saxon" <ronfaxon@example.com>]

David Bernat wrote:

> > [LHS] Better than nothing... does anyone else out there have additional
> > information?  It's not going to come from the manufacturers responsible,
> > so it has to come from us.
> >    
>
> http://www.siliconchip.com.au/cms/A_30328/article.html

Very interesting site:

/http://www.siliconchip.com.au/cms/A_30328/article.html
Motherboard Capacitor Problem Blows Up
By Peter Smith./


Quoting from that page:

    /"Initially, there were only two clues to the mystery. First, the 
failing capacitors were more often that not to be found in the power 
supply section of motherboards. The capacitors used in this area are 
characterised by their need to have very low ESR (Equivalent Series 
Resistance- see panel).
    Second, most of the failing capacitors were identified as Taiwanese 
in origin. That's not too surprising at first glance, as Taiwan 
manufactures about 30% of the world's aluminium electrolytics (22.5 
billion a year).
    In September, "Passive Industry Components Magazine" published a 
story that exposed the reasons behind the unusually high failure rates. 
They reported that the failures were directly related to the use of 
faulty electrolytes in the manufacturing process.
Industrial espionage?
    The story describing how the electrolytes came to be faulty reads 
like a lot of fiction. It begins in Japan, at a major capacitor 
manufacturer. A materials scientist for the Japanese company resigned 
and went to work for a Chinese capacitor manufacturer. While there, he 
reproduced one of the electrolytes used in his former employer's premium 
(low-ESR) aluminium electrolytic products.
    Staff working with the scientist then defected, taking the secret 
electrolyte formula with them. They used the formula to manufacture 
their own electrolyte, which they subsequently flogged to major 
Taiwanese capacitor manufacturers at bargain prices. Unfortunately, 
their reproduction of the formula was flawed and the rest is history."/

Espionage!  Japanese scientist defect to China!  Trade secrets leaked to 
Taiwan!  Why isn't this in the mainstream news and on TV, with reporters 
crowded around the Japanese manufacturer (Nichicon, of Kyoto?) and with 
other reporters being sent to China and Taiwan to track down the 
scientist who defected and the company (companies?) in Taiwan which 
bought the technology from China?  If it's true, it's better than 
fiction.  If it's not true, let's here the companies involved refute it 
and give the real reasons!


    /"As mentioned earlier, these capacitors are of a specific type; 
they have very low ESR. To understand the need for this requirement, 
let's take a brief look at the circuitry involved.
    Low-ESR capacitors.  Probably due to the fact that CPU core 
voltages change so often, designers have been forced to implement 
sections of the power supply circuitry on the motherboard. The standard 
power supply box still provides the usual 12V, 5V and 3.3V rails, but 
the lower voltages for the CPU core are provided by further step-down 
circuitry on the motherboard.
    This on-board switchmode step-down circuitry runs at high 
frequencies (over 100kHz) to minimise the required inductance and filter 
capacitance. A key ingredient in this recipe is physically small 
electrolytic capacitors that can handle high ripple currents at high 
frequencies. In short, they must have very low impedance at the 
switching frequency."/

Here we go.  Just as I suspected!  They are not just any old capacitors, 
but rather of a special type!


    /"The "Rubycon" (Japanese) brand ZL and ZA series ultra-low 
impedance capacitors will be suitable in most cases. They're available 
locally from Farnell Electronic Components - see Farnell's web site at 
www.farnell.com for more information.
    Caution: the standard ZL and ZA series may be marginally larger in 
diameter than the original parts (10mm versus 8mm).
    All electrolytic capacitors have a finite life, measured in 
thousands of hours. Unlike the exceptional cases discussed in this 
article, there are usually no external signs that a capacitor is nearing 
its end of life. However, it is possible to determine whether a 
capacitor is serviceable or not by measuring it's ESR (Equivalent Series 
Resistance)."/

So... where to get the replacement capacitors for my new custom-built 
box?  Any recommendations?

Lyle