On Mon, 18 Oct 2021 00:30:39 -0700 (PDT), skybuck2000 <skybuck2000@hotmail.com> wrote:>Ever heard of such a thing ? > >This is one of my hypotheses why there is brown stuff on top of a backup motherboard that was inside a box in a closest for many years, at least 10 years, possibly more. > >However it was bought second-hand, so could also be that previous owner ran it very hot, though it seems more likely that any brown stuff would be wiped off before it would be put into the bag ? > >So this leads me to this bacteria hypothesis that it formed gasses inside the capacitator and made this brown stuff bubble up.The hard brown stuff on the outside of an electrolytic capacitor is the glue used to hold it to the PCB so that it doesn't fall over during wave soldering. However, the electrolyte does leak: <https://www.capacitorlab.com/visible-failures/> "The electrolyte discharge can also be larger covering the top of the cap with a dried substance which can be black, orange, brown, white or a similar colour." From my experience, the stuff that leaks out the top is usually white or yellow, while the stuff that leaks out the bottom is dark brown or black, presumably from the electrolyte reacting with the rubber plug. Drivel: If you think that bacteria, mold, or fungus are attacking your tools, that's also wrong. Here's some "white plastic rot": <http://www.learnbydestroying.com/jeffl/pics/white-plastic-rot/index.html> I recently bought about 50 assorted nut drivers and screwdrivers for very little because the owner thought the white plastic rot was dangerous. It took me a few minutes with Scotch-Brite and a bench buffer to make them look almost like new. -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558
Are there bacteria inside old electrolytic capacitators ?
Started by ●October 18, 2021
Reply by ●October 19, 20212021-10-19
Reply by ●October 19, 20212021-10-19
On Mon, 18 Oct 2021 00:30:39 -0700 (PDT), skybuck2000 <skybuck2000@hotmail.com> wrote:>So this leads me to this bacteria hypothesis that it formed gasses inside the capacitator and made this brown >stuff bubble up.The bubbling from within the capacitors is likely the result of "capacitor plague", which is an electrochemical reaction that doesn't require the activity of bacteria. It's caused by a bad (incomplete) electrolyte formula, which lacks stabilizers to protect the aluminum electrodes from corrosion. The corrosion process releases hydrogen gas and eventually causes the caps to vent. https://en.wikipedia.org/wiki/Capacitor_plague
Reply by ●October 19, 20212021-10-19
On Tue, 19 Oct 2021 15:14:15 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:>On Mon, 18 Oct 2021 00:30:39 -0700 (PDT), skybuck2000 ><skybuck2000@hotmail.com> wrote: > >>Ever heard of such a thing ? >> >>This is one of my hypotheses why there is brown stuff on top of a backup motherboard that was inside a box in a closest for many years, at least 10 years, possibly more. >> >>However it was bought second-hand, so could also be that previous owner ran it very hot, though it seems more likely that any brown stuff would be wiped off before it would be put into the bag ? >> >>So this leads me to this bacteria hypothesis that it formed gasses inside the capacitator and made this brown stuff bubble up. > >The hard brown stuff on the outside of an electrolytic capacitor is >the glue used to hold it to the PCB so that it doesn't fall over >during wave soldering. > >However, the electrolyte does leak: ><https://www.capacitorlab.com/visible-failures/> > "The electrolyte discharge can also be larger > covering the top of the cap with a dried substance > which can be black, orange, brown, white or a > similar colour." > >From my experience, the stuff that leaks out the top is usually white >or yellow, while the stuff that leaks out the bottom is dark brown or >black, presumably from the electrolyte reacting with the rubber plug. > >Drivel: If you think that bacteria, mold, or fungus are attacking >your tools, that's also wrong. Here's some "white plastic rot": ><http://www.learnbydestroying.com/jeffl/pics/white-plastic-rot/index.html> >I recently bought about 50 assorted nut drivers and screwdrivers for >very little because the owner thought the white plastic rot was >dangerous. It took me a few minutes with Scotch-Brite and a bench >buffer to make them look almost like new.I've seen that too. I find that hot water and scrubbing with a white scotchbrite pad takes the fungus off; no buffing needed. Joe Gwinn
Reply by ●October 19, 20212021-10-19
On Tue, 19 Oct 2021 19:32:31 -0400, Joe Gwinn <joegwinn@comcast.net> wrote:>On Tue, 19 Oct 2021 15:14:15 -0700, Jeff Liebermann <jeffl@cruzio.com> >wrote: >>Drivel: If you think that bacteria, mold, or fungus are attacking >>your tools, that's also wrong. Here's some "white plastic rot": >><http://www.learnbydestroying.com/jeffl/pics/white-plastic-rot/index.html> >>I recently bought about 50 assorted nut drivers and screwdrivers for >>very little because the owner thought the white plastic rot was >>dangerous. It took me a few minutes with Scotch-Brite and a bench >>buffer to make them look almost like new.>I've seen that too. I find that hot water and scrubbing with a white >scotchbrite pad takes the fungus off; no buffing needed. > >Joe GwinnIt's not bacteria, mold, or fungus. Look at my microscope photos and see if you can recognize anything that might be alive. My best guess is that it's some kind of decomposition of the acrylic (cellulose acetate butyrate) plastic. If I scrape off some of white stuff, it will dissolve in acetone, exactly like the base CAB plastic. When I gave the handle an acetone vapor wash, the white stuff "melted" into a smooth glossy surface. Bacteria, mold or fungus doesn't act like that. Also, older tool handles smell like vomit: <https://toolguyd.com/why-hard-plastic-screwdriver-handles-smell-like-vomit/> -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 19, 20212021-10-19
On Tue, 19 Oct 2021 17:38:11 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:>On Tue, 19 Oct 2021 19:32:31 -0400, Joe Gwinn <joegwinn@comcast.net> >wrote: > >>On Tue, 19 Oct 2021 15:14:15 -0700, Jeff Liebermann <jeffl@cruzio.com> >>wrote: >>>Drivel: If you think that bacteria, mold, or fungus are attacking >>>your tools, that's also wrong. Here's some "white plastic rot": >>><http://www.learnbydestroying.com/jeffl/pics/white-plastic-rot/index.html> >>>I recently bought about 50 assorted nut drivers and screwdrivers for >>>very little because the owner thought the white plastic rot was >>>dangerous. It took me a few minutes with Scotch-Brite and a bench >>>buffer to make them look almost like new. > >>I've seen that too. I find that hot water and scrubbing with a white >>scotchbrite pad takes the fungus off; no buffing needed. >> >>Joe Gwinn > >It's not bacteria, mold, or fungus. Look at my microscope photos and >see if you can recognize anything that might be alive. My best guess >is that it's some kind of decomposition of the acrylic (cellulose >acetate butyrate) plastic. If I scrape off some of white stuff, it >will dissolve in acetone, exactly like the base CAB plastic. When I >gave the handle an acetone vapor wash, the white stuff "melted" into a >smooth glossy surface. Bacteria, mold or fungus doesn't act like >that.I looked. It does not look like what has been happening to my Xcelite screwdrivers, and Craftsman to a lesser extent. I'd guess that the white stuff is some kind of plasticizer. What often works is naptha (lighter fluid); this will not dissolve the base resin. Also try alcohol.>Also, older tool handles smell like vomit: ><https://toolguyd.com/why-hard-plastic-screwdriver-handles-smell-like-vomit/>The vomit smell is definitely Butyrate resins. This cannot be fixed, except by replacement of the handle. Joe Gwinn
