Protecting big caps with... silicone?

[überfuzz]

I'm looking for something to glue electrolytic caps with, to reduce vibrations. Is there anyone here with a good advice of what to get?

[Jazz P Bass]

Silicone works really well.
Kind of stinky until it dries.
I have used water soluble "indoor window caulking".
It is a lot easier to clean up & it does not stink up the shop.

[überfuzz]

Mhmm, I guess I'll get the first thing I get my hands on.

Usually I use a heat resilient windows sealing, but it this particular build the filter caps are mounted on the main board. So I can't 'seal' the caps in a good way.

[JoeM]

I'd use hot glue. Certain silicon glues can cause problems, something to do with the way it cures. (Acetic acid). There are kinds that do work OK.

Some info here, (not specific to guitar amps though):

AnaLog Services RTV Silicones

[Mark Black]

Besides possible corrosion issues (which I've never personally experienced), bear in mind that some (maybe most - I don't know) silicone adhesives can be electrically conductive until cured. I know this from my own experience and through talking with other techs who also learned the hard way.

Silicone is still my favorite for tacking down things like big caps, but I try to keep from bridging any high-voltage connections with it unless I know I can put the job aside for a full cure before testing.

Hot glue has its place, but it doesn't seem to stick to anything smooth well enough to truly secure it for the long haul (loose caps & coils in numerous speaker crossovers come to mind), and of course if it gets hot enough it returns to a liquid.

[überfuzz]

I found out that a local dealer has a silicone based glue, or tack grease. (Don't know the English word...) I think I'll go with that.

Thanks for all input, it helped a lot!

[tedmich]

I have heard a few descriptions of failed amps with gobs of automotive (silicone) RTV adhesives on them. Some of the automotive gasketing RTVs actually have metallic fillers to help their high temp handling (head gaskets get HOT!) and thus conduct electricity. All (pure) cured silicone adhesives are completely dielectric and excellent insulators up to ~400C.

The vinegar smelling (acetic acid / acetoxy cure) RTVs corrode electronics with their acidic fumes while other chemistry (usually called "low odor") is much better for electronics. Dow Corning 748 is a common one part electronics grade silicone that sells for ~$15 for a big cartridge (McMaster Carr has it). Hi melt temp "hot melt adhesives" work really well too, Peavey has used these for years.

[Albert Kreuzer]

Just don't overdo it. I suspect some kinds of that stuff to get conductive over time.
This amp (Bassman 135) had almost zero output when it came to me. After cleaning up it worked like new.

[Mark Black]

Nice work Albert!

That must have taken quite a while...

[defaced]

What about polyurethane based construction adhesives like liquid nails or similar?

[Albert Kreuzer]

That must have taken quite a while...

Yep.
Hot melt glue is much easier to remove (freeze spray).

But it was worth it. Cool amp.

[tedmich]

What about polyurethane based construction adhesives like liquid nails or similar?

should work fine if it doesn't foam up too much, IME urethane glues die horribly with ANY UV but should be aok in the dark amp guts.

[Rick Erickson]

Mark - A little Naptha works wonders in cleaning up dried Silicone. I keep some in an old ink cart. refill bottle and use the needle tip to inject it into the silicone blob. Hot melt is a bad idea in any application where it encounters heat. Witness all the Trace Elliot & Orange (same company) amps with bad connections due to the hot melt seeping into the pc board connectors.

[überfuzz]

The stuff I ended up buying was silicon to be used as gasket in car-engines. Works like a charm! Stays rubbery and takes the heat, over 300 C.

[J M Fahey]

When I started (don't ask) , neither silicone nor hot melt had yet been invented (nor Loctite) so I always used (still do) neoprene rubber cement to glue electrolytics and transformers to boards or chassis , as well as vibration/flex proofing wires, and a drop of Nitro transparent lacquer to fix anything that screws on (screws/nuts, jack nuts, pot nuts, plug sleeves, etc,)
Beauty is that when unassembly is needed, a little extra effort snaps/cracks it open with no further trouble ... and is way more temperature resistant than hot melt.
Ah !!, and I still make my arrow points in silex, tied with real cat gut, and glued with boiled fish hide, but that belongs into another forum []