Sanyo Blue Caps in Pioneer Receivers

tinkerer

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I've noticed that the recommended replacement for the troublesome Sanyo blue caps is a film cap. Why is that? What are the effects of replacing them with electrolytic caps?
 
Pioneer often used these Sanyo "solid aluminum" capacitors in the signal path. A film capacitor is better than any electrolytic type in the signal path, e.g., lower leakage & distortion.
 
Most of the Sanyo's were of a capacitance that newer film caps could be substituted in the space provided - a lot of those sanyo's were less than 1 uF, so the rule of thumb of 0.1uf to 1.0uf gets film caps applies.

What are the effects of replacing them (Sanyo's) with electrolytic caps?
Same old same old... CAN be done - but when better alternatives exist than when the unit was designed, why??
Bottom line: film caps pass cleaner sound (the highs) AND never need to be replaced again.

read this ( well, a small part of it):
https://en.wikipedia.org/wiki/Film_capacitor

Film capacitors are made out of two pieces of plastic film covered with metallic electrodes, wound into a cylindrical shaped winding, with terminals attached, and then encapsulated. In general, film capacitors are not polarized, so the two terminals are interchangeable.

A key advantage of modern film capacitor internal construction is direct contact to the electrodes on both ends of the winding. This contact keeps all current paths to the entire electrode very short. The setup behaves like a large number of individual capacitors connected in parallel, thus reducing the internal ohmic losses (ESR) and the parasitic inductance (ESL). The inherent geometry of film capacitor structure results in very low ohmic losses and a very low parasitic inductance,

Winding — Two films are rolled together into a cylindrical winding. The two metallized films that make up a capacitor are wound slightly offset from each other, so that by the arrangement of the electrodes one edge of the metallization on each end of the winding extends out laterally.

Application of metallic contact layer ("schoopage") — The projecting end electrodes are covered with a liquefied contact metal such as zinc or aluminum, which is sprayed with compressed air on both lateral ends of the winding. This metallizing process is named schoopage after Swiss engineer Max Schoop, who invented a combustion spray application for tin and lead

Which is what we want for quality audio.
The construction is key, the material (polypropylene vs polyester) is secondary.

Electrolytic caps are wound too (think of a roll of toilet paper), BUT there is only one connection point to each of two foils in their entire tightly coiled length.
What else is a conductive current carrying element, that is coiled upon itself so the magnetic fields of the current can interact??? I got it - an INDUCTOR!!!!
And WHAT is death on high frequencies - an INDUCTOR!!!
easy peasey.
Film caps minimize inductance.
 
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does the failure rate of these caps apply to the larger value blue sanyos as well? say 15 or so mfds?

It is specific to the chemistry technology Sanyo used, and how long it took Sanyo to realize they had a severe problem AFTER they started failing..
I think it was an attempt to make tantalum type capacitors using aluminum, i.e. "solid aluminum capacitors". Small size, lots of capacitance, cheaper than tantalum. I cannot dig up enough on line in the appropriate time period.
Pioneer differentiated them by the CSSA capacitor type code in the parts lists.

https://en.wikipedia.org/wiki/Tantalum_capacitor

https://en.wikipedia.org/wiki/Polymer_capacitor
 
Reliability was I believe a Sanyo part issue not the actual technology per se.
I used some very high reliability Philips solid aluminum ecap in a design I did years ago. I recall they were a premium cost over a std tantalum. I wonder how they are holding up, they went into some telecom gear we designed for the Thailand railways system
I see Vishay just discontinued this 128 SAL-RPM series
http://www.vishay.com/docs/28354/128salrpm.pdf
Useful life at 40 °C, IR applied > 300 000 h. That works out to ~34 years, not too bad.
 
When I researched that part the best I could come up with was organic polymer, and a starting date of 1983 which is much later than most of the Receivers that have these problematic caps in them. I don't know WHAT the bleep they are, other than Pioneer calling them CSSA and solid aluminum. I am too time constricted now to cut a few up from my reference library of removed parts to get a look at their guts.
 
I cut one of these in pieces (or it was a white Elna) and afaik I put a picture in the cap abyss thread a year or so ago
 
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