I've never seen a capacitor that looks like this, and I known blown ones are either in pieces or typically bulging. This looks like compound I've seen on CRT rings and pots, put there by the factory to show something has been calibrated and not moved since, but why would they put it on a cap like this? Just to show it's original?

enter image description here

I'm assuming of course that I'm not way off base and this cap is blown. This is a 100V power board that I'm reasonably sure has been connected to a 220V source at some point, the fuse to the left is clearly blown.

  • \$\begingroup\$ Yep, this question is answered there. \$\endgroup\$
    – Techydude
    May 30, 2015 at 12:12
  • 1
    \$\begingroup\$ I'm a stackexchange mod myself, definitely close enough for a dupe. I never thought to search for ' white stuff' :) \$\endgroup\$
    – Matt Lacey
    May 30, 2015 at 12:47
  • \$\begingroup\$ The fuse is blown, but the board is marked as 1.6A @250V. If this is the fuse ratings, 220V wouldn't blow fuse. \$\endgroup\$ May 30, 2015 at 17:31
  • \$\begingroup\$ Good point. I'll replace the fuse and try it with a step-down transformer to see if it's survived. \$\endgroup\$
    – Matt Lacey
    May 30, 2015 at 23:43

1 Answer 1


That's sometime affectionately known as "Gorilla Snot" (hereafter "GS"). It's a relatively fast setting adhesive that is INTENDED to provide mechanical strength and/or rigidity to parts that should have been given it by proper means such as brackets or support rings, BUT they decide that they can get away with doing it on the cheap with this material. (Draws breath). They can and they can't. It tends to fail long term in many cases when stressed. If it doesn't fail it probably wasn't needed.

Sometimes used instead and no less effective is "hot melt" glue, applied at moderate temperature and sets as it cools. Like GS it too almost always fails in the medium to long term. Usually in months, sometimes weeks. It seems that the glue (aka melted plastic) hardens with time and loses any keying it has to most surfaces. It can be used with some utility by allowing it to pass through a hole or slot and to accumulate a "knob" or bulge on the other side, so that WHEN it releases the knob is too large to pass through the hole or slot. Such an arrangement could provide reasonable retention although maintaining tight positional tolerances may be difficult.

In my experience, a superior solution is to use a neutral cure silicone rubber. Extensive advice is available from manufacturers on what grades to use with various materials and conditions. Primers are available for some harder to bond materials. In most cases I have found that silicone rubbers provide superb long term seals and bonds. 20+ year sealing and retention in outdoor plumbing type use is common.

An exception I found was in attempting to bond a FR4 PCB backed PV panel into an ABS well in a portable light housing. Over time the ABS/silicone-rubber join would debond, just as GS and hot-melt glue do. In that case it was possible to key the rubber into holes in the housing so that retention knobs were formed, as mentioned above.

  • \$\begingroup\$ On the duplicate I flagged you already have an answer posted three years ago. That looks like a good answer with quite a few upvotes already so wouldn't it be better just to update that and keep all the information in one place? \$\endgroup\$
    – PeterJ
    May 30, 2015 at 12:17
  • \$\begingroup\$ @PeterJ I've amended the othetr answer as well BUT the focus is subtly different and unless they are either very clearly linked and/or well tagged a searcher may find the wrong one only. (1) One has a faulty PCBA and wonders if the white goo relates to a fault. (2) The other has white goo and asks why the factory would add it. ie fault versus factory action. (3) JFK looks at things that never were, and asks, "Why not" :-) \$\endgroup\$
    – Russell McMahon
    May 30, 2015 at 12:31
  • \$\begingroup\$ Hi Russell, you might have a bit of a misunderstanding what happens to duplicate questions, unlike say unclear / off-topic etc they're not deleted automatically so they remain visible to Google / tag searches etc for the very reason they can be useful for future people. So by closing as a duplicate the asker gets a quick pointer to a similar question with multiple answers that are well vetted, and anyone in the future searching using the same terms will find it too. \$\endgroup\$
    – PeterJ
    May 30, 2015 at 12:40
  • \$\begingroup\$ @RussellMcMahon JFK? Ask snot what your gorilla can do for you? \$\endgroup\$ May 30, 2015 at 12:44
  • \$\begingroup\$ @PeterJ I might have. But mayhaps not always. I have seen questions deleted from the public eye - sometimes for reasons which made minimal sense to me.I have had (on SE but not in this group) questions of mine deleted without comment or discussion for given reasons which may seem specious at best on a fine day downhill with the wind behind you. best on \$\endgroup\$
    – Russell McMahon
    May 31, 2015 at 8:25

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