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MOLDY CAPACITORS
- Thread starter Sonar
- Start date
no, but it could be corrosion with some type of moisture and the aluminum on the capacitor.
or
if the cap has a lump on it, it has likely failed and the inside has leaked a bit.
or
if the cap has a lump on it, it has likely failed and the inside has leaked a bit.
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Heck,.......... when he started talkin about "green polyester"and "the 70's" I was thinkin about disco
is there any brown glue attached to these capacitors that have the "mold" on them?
if so, it's not mold, it's corrosion due to that glue becoming conductive. (it will eventually)
LC
if so, it's not mold, it's corrosion due to that glue becoming conductive. (it will eventually)
LC
@ 1:15 As you desribed it... They need replacing!!
Good video he talks about the caps failing...
im finding this very interesting, and im now wondering why ive never seen this before.
pretty much everything i work on aside from galaxy radios is from that era.
i wonder if living in the desert has any effect on how these caps age.
i did find something that might be a first clue as to what is going on, and that is a possible name for this white powder.
"polytetrafluorethylene (say that three times fast!) - a white powder that can be moulded or extruded. highly resistant to moisture and chemicals, withstands temperatures up to 250*C. low loss, high-frequency application."
i found this in an electrical engineers reference book. not sure if this is the stuff, but maybe a place to start.
i am also finding references to "chlorinated polypropylene" which is a white powder that might be used in making these caps.
i will keep digging.
LC
pretty much everything i work on aside from galaxy radios is from that era.
i wonder if living in the desert has any effect on how these caps age.
i did find something that might be a first clue as to what is going on, and that is a possible name for this white powder.
"polytetrafluorethylene (say that three times fast!) - a white powder that can be moulded or extruded. highly resistant to moisture and chemicals, withstands temperatures up to 250*C. low loss, high-frequency application."
i found this in an electrical engineers reference book. not sure if this is the stuff, but maybe a place to start.
i am also finding references to "chlorinated polypropylene" which is a white powder that might be used in making these caps.
i will keep digging.
LC
I can only guess that with shifting/changing temps, humidity, and time caused the epoxy seal to break open and allowed the inner compounds to bind to the outside via a static charge. Possibly expanded from the inside thereby cracking the epoxy shell due to excessive humidity absorption? Never seen this before, as polypropylene caps have a history of being pretty hardy. Then again, my environment is pretty dry; not excessively humid like the East Coast or the South US.
The new poly caps are self-healing; interesting read if one looks into it:
http://www.novascholar.com/pdfs/citeseerx/citeseerx3/ours/368761.pdf
The new poly caps are self-healing; interesting read if one looks into it:
http://www.novascholar.com/pdfs/citeseerx/citeseerx3/ours/368761.pdf
I wouldn't be surprised if you're on the right track or even nailed it. Thumbs up on the follow-up/research.
I highly doubt that is what it is. PTFE is commonly known as Teflon and although it may start off as a powder once manufactured into Teflon it does not break back down into a white powder again. I have seen similar "mold" on other components including metal coils cases. I suspected it was from the changes in humidity and dust infiltration. The hard smooth plastic cases of the caps would be quite damp feeling after a large temperature swing from cold to warm.
yeah CK, im pretty sure you are right. the more i read about it last night, the more i kept finding the word teflon. LOL
what about the chlorinated polypropylene? any chance im on the right track with that one?
LC
Chlorinated polypropylene is a transparent, hard and brittle thermoplastic resin.When applied it makes a transparent, hard glass like film, which is resistant to the permeation of moisture and air and also shows high chemical resistance. Chlorinated Polypropylene protects the underlying materials from corrosion and also serves as a top coating for decorative purpose.It is also used in paints and inks to improve the adhesion qualities. Because of these qualities I highly doubt it is that which is forming on the outside of the caps.
