Glue on the filter caps

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dragonbat13
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Glue on the filter caps

Post by dragonbat13 »

I don't use it on my recaps and builds.

Is it really worth it? I don't see how an amp could actually benefit from this.

Is it a thing that happens on world tour, Van Circuit, never off the road amps?

I'm just wondering why I see some with it and some without.
Mark Clay

Amature/Hobbyist/Electronics Hoarder
alnight
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Re: Glue on the filter caps

Post by alnight »

I have built with and without. I think it's a good idea in a Marshall type situation where the amp lives "upside down" with its tubes in the air and the caps are basically suspended by their leads against gravity. Otherwise I don't know that it makes all that much difference. If I've got a tube of high temp silicone on the table when I'm building these days, I'll put a dab on, especially if I'm building an amp for someone else.
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martin manning
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Re: Glue on the filter caps

Post by martin manning »

Amps that are constantly subjected to a high vibration environment are at some risk. Components supported by their leads can vibrate in resonance, causing their leads to fatigue and break. IMO it’s cheap insurance to add a dab of silicone to secure parts with relatively large mass and supported only by their leads (like caps), that might have resonances in the audio range.
Last edited by martin manning on Tue Sep 02, 2025 1:50 pm, edited 1 time in total.
jabguit
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Re: Glue on the filter caps

Post by jabguit »

especially big 100n orange drop caps are prone to wiggling and breaking their leads. happened to a couple amps I've owned over the years...

my $0.02
Jack Briggs
Briggs Guitars
maxkracht
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Re: Glue on the filter caps

Post by maxkracht »

I've repaired a lot of amps where a lead snapped from a cap due to vibration. No need to goop an amp as heavily as they do in some factories, but a dab of silicone really helps with any remotely heavy components that don't have much of their own support.

I will also note, silicone isn't a replacement for mechanical support, it should be in addition to, and you need to clean the surface for glue. I just worked on an old amp that had been recapped with axials connected to a terminal strip only by the negative side, positive side J hooked to wires. The caps were siliconed in place, but the silicone had failed from grease/dirt on the chassis leaving heavy axials hanging from a single wire. This might be fine for a home/studio amp, but it wouldn't survive gigging.
timrobertson100
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Re: Glue on the filter caps

Post by timrobertson100 »

Is any old silicon suitable for the parts we use please (e.g. bathroom / kitchen silicone caulk)?
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martin manning
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Re: Glue on the filter caps

Post by martin manning »

Use non-corrosive type suitable for electronics. Automotive gasket sealer products of this type are labeled "sensor safe"
nuke
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Re: Glue on the filter caps

Post by nuke »

This is perfect:

https://www.amazon.com/dp/B0063U2RT8?re ... in_title_1

ASI #388 electronics grade silicone.

No acetic acid, non-corrosive. Strong, yet removable. Reasonable price.
maxkracht
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Re: Glue on the filter caps

Post by maxkracht »

In case anyone else has struggled with storing a partly used tube of silicone, my go to methods for the past few years are:

Stretch a piece of electrical tape over the opening then screw the cap back on, making sure you didn't trap any air inside. Or, if you don't have electrical tape, squeeze out some extra silicone then put the cap back on allowing the silicone to cure around the cap but not inside. RTV cures from moisture in the air, so any air tight seal will work. Those are just the most convenient and effective ways I have found. Just the cap never seems to do the trick. Electrical tape will keep it fresh for weeks, if not months, between uses.
SoulFetish
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Re: Glue on the filter caps

Post by SoulFetish »

maxkracht wrote: Wed Sep 03, 2025 3:02 am In case anyone else has struggled with storing a partly used tube of silicone, my go to methods for the past few years are:

Stretch a piece of electrical tape over the opening then screw the cap back on, making sure you didn't trap any air inside. Or, if you don't have electrical tape, squeeze out some extra silicone then put the cap back on allowing the silicone to cure around the cap but not inside. RTV cures from moisture in the air, so any air tight seal will work. Those are just the most convenient and effective ways I have found. Just the cap never seems to do the trick. Electrical tape will keep it fresh for weeks, if not months, between uses.
I made “pokers” using heavy gauge romex and fashioned eye hooks so they’re easy to hang up. If the silicone cures it’s usually only a few millimeters deep and you can get at it pretty easily
TUBEDUDE
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Re: Glue on the filter caps

Post by TUBEDUDE »

maxkracht wrote: Wed Sep 03, 2025 3:02 am In case anyone else has struggled with storing a partly used tube of silicone, my go to methods for the past few years are:

Stretch a piece of electrical tape over the opening then screw the cap back on, making sure you didn't trap any air inside. Or, if you don't have electrical tape, squeeze out some extra silicone then put the cap back on allowing the silicone to cure around the cap but not inside. RTV cures from moisture in the air, so any air tight seal will work. Those are just the most convenient and effective ways I have found. Just the cap never seems to do the trick. Electrical tape will keep it fresh for weeks, if not months, between uses.
I use kitchen plastic wrap.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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