gunk holding led's in place

[fogwolf]

Does anyone know what the yellowish (and the black as well) gunk holding in the led's in this photo would be:

http://www.generalguitargadgets.com/pics/amp_aby_inside3.jpg

Also on a similar note, how do all of you hold the led's in your pedals in place?

Thanks!

[GibsonGM]

Looks like some kind of expoxy.  You could use that, or a hot glue gun...at times I've used silicone RTV sealant, which is fairly sturdy but allows you to remove the LED if you have to work on the circuit later...

[petemoore]

  Also on a similar note, how do all of you hold the led's in your pedals in place?
  Hard cardboard pins body ridge down, that or small perfboard, stick the legs through non-conductive substrate..glue...cardboard bends nice.
  Hotmelt glue, even Elmers...
  If the hole is drilled just right, stiff pressure secures it well, or add about 1/50 the volume of expoxy shown to the sides / body ridge..where the glue has very short span distance or touches the two surfaces to be manhandled, it gets that 'full circumferance leverage' thing going on......just seems less messy and neater to only use a really small round of glue-poxy...put LED in, but leave it not in all the way, just out far enough to get adhesive around the touch circle [I use a slightly split, bent-end toothpick to irrigate the adhesive application for 'under and around the corner glue jobs], press in the rest of the way let dry, hammer blow might break it but will probably press it out...probably about what you want.
  those are the left ways
  the other way is why they make LED bezels, I just don't use 'em.

[ClinchFX]

silicone works well, as long as you use a neutral cure silicone.  The down side is that it takes so long to cure.

I prefer hot melt glue.

Beware of adhesives that go brown with age.  Many of them become conductive as they go brown and cause intermittent problems.  This was a classic issue with 80s VCRs from at least one Japanese manufacturer.  The PCB had mods where a component was soldered to the back of the board and stuck down with glue.

Peter.

[fogwolf]

Thanks for the replies. What size bit do you use to drill your led holes? Also, this is probably a really dumb question, but there's not a problem with snipping the length of the leads on an led, is there? I'm assuming since you do it for other components it would be fine. Do you then just bury it in the epoxy or whatever you're using to hold them in place? petemoore says something about maybe using cardboard to hold the leads but I couldn't quite follow.

silicone works well, as long as you use a neutral cure silicone.  The down side is that it takes so long to cure.

I prefer hot melt glue.

Beware of adhesives that go brown with age.  Many of them become conductive as they go brown and cause intermittent problems.  This was a classic issue with 80s VCRs from at least one Japanese manufacturer.  The PCB had mods where a component was soldered to the back of the board and stuck down with glue.

Peter.

[ClinchFX]

I try not to cut the leads too short if I'm soldering directly to the leads.  For my production pedals, I've begun using a 2 pin socket that just plugs on to the leads.  I can't find a picture right now, but it is similar to the type of plug that you see for connecting to 2 pin headers on computer motherboards.  The leads of the LED go right through, and I then trim them.

If I solder to the LED leads, I leave them fairly long, and put heatshrink over the joint right to the bottom of the LED.  I've been known to use cardboard as temporary insulation in prototypes, but never in a production pedal.

The mounting hole will depend on the diameter of the LED you are using, and whether you are using a mounting bush.  I use 3mm LEDs with a mounting bush that requires a 4.5mm hole.  If you don't use a mounting bush, just drill the exact size of the LED.  You can try drilling a hole in a piece of scrap metal first, to see if it is correct.

Peter.

[Jered]

  Why don't you want to use LED bezels? They're quick, easy, and cheap. I prefer the chrome bezels but the plastic work great too. To easy NOT to use.
  Jered

[Naz Nomad]

+1 for chrome bezels ... but I guess it depends on individual taste.

[fogwolf]

How do the bezels work?

  Why don't you want to use LED bezels? They're quick, easy, and cheap. I prefer the chrome bezels but the plastic work great too. To easy NOT to use.
  Jered

[ayayay!]

I like the bezels from www.effectsconnection.com    For 5mm LEDs, I drill a 1/4" hole for really thin casings, and a 9/32" hole for thicker casings.  Always drill the smaller hole first and try it.  If it doesn't fit after you really try to cram it in there, then proceed to 9/32".  (5/16" will almost definitely be too big)

The chrome bezels are great if you REALLY need the LEDs to be secure.  I don't like the way they look, but they're pretty much goof-proof.  You can get the chrome bezels and some cheap LED holders at Radio Shack.   

[yeeshkul]

I use chrome LED holders. The problem is that you cannot tighten it too much because it can damage the art sticker on top of the box and looks awfull - especially laminated stickers go white around the visible part of the LED-holder. So i usualy tighten the nut a bit loose + use star washer + put a blob of epoxy all around to keep it tight. It works.

[fogwolf]

So do you shrink the heatshrink tubes you put over the leads? Do you just heat them by holding the soldering iron close? Then I'm guessing you bend them down flat against the casing - anything to hold them in place there (epoxy, like in the original photo I included a link to) or will the bevels work well enough?

Thanks again.

I try not to cut the leads too short if I'm soldering directly to the leads.  For my production pedals, I've begun using a 2 pin socket that just plugs on to the leads.  I can't find a picture right now, but it is similar to the type of plug that you see for connecting to 2 pin headers on computer motherboards.  The leads of the LED go right through, and I then trim them.

If I solder to the LED leads, I leave them fairly long, and put heatshrink over the joint right to the bottom of the LED.  I've been known to use cardboard as temporary insulation in prototypes, but never in a production pedal.

The mounting hole will depend on the diameter of the LED you are using, and whether you are using a mounting bush.  I use 3mm LEDs with a mounting bush that requires a 4.5mm hole.  If you don't use a mounting bush, just drill the exact size of the LED.  You can try drilling a hole in a piece of scrap metal first, to see if it is correct.

Peter.

[fogwolf]

In addition to my question about melting the heat shrink with a solder gun, do you not cover the entire lead with heat shrink? Why only from the join up to the light? Also, what size heat shrink would I want for leds? For example, would this be too small:

http://www.amazon.com/3M-Black-Heat-Shrink-Tubing/dp/B0002BA3ZO/ref=sr_1_44?ie=UTF8&s=electronics&qid=1213288437&sr=8-44

It's 1/16" & is 2:1, so it would shrink to 1/32". Would it be better to get 1/8" 2:1? Also I'm guessing when I buy a 4' roll like this I simply cut off the sizes I need.

Thanks again. I know I have a lot of questions but really want to do this right - my first attempt with dealing with getting my leds to lie flat beneath the pcb and to insulate them didn't turn out so well.

I try not to cut the leads too short if I'm soldering directly to the leads.  For my production pedals, I've begun using a 2 pin socket that just plugs on to the leads.  I can't find a picture right now, but it is similar to the type of plug that you see for connecting to 2 pin headers on computer motherboards.  The leads of the LED go right through, and I then trim them.

If I solder to the LED leads, I leave them fairly long, and put heatshrink over the joint right to the bottom of the LED.  I've been known to use cardboard as temporary insulation in prototypes, but never in a production pedal.

The mounting hole will depend on the diameter of the LED you are using, and whether you are using a mounting bush.  I use 3mm LEDs with a mounting bush that requires a 4.5mm hole.  If you don't use a mounting bush, just drill the exact size of the LED.  You can try drilling a hole in a piece of scrap metal first, to see if it is correct.

Peter.

[ayayay!]

DO NOT use your soldering iron or gun for heatshrink tubing.  Use a lighter, keeping the top of the flame about 1 inch away from the tubing.  Bring it slowly towards the tubing, but don't let the flame touch it or it will smoke & smolder something awful.  If you use your gun you'll be tempted to get it really close to the tubing, and then you may end up with nasty rubberized goop on your tip.  Blech. 

I think I use 1/8" tubing but can't remember.  Yes, you just cut off what you need.  Just remember to slip the tubing over the leads BEFORE you solder.     Yes, the bezels will hold the LEDs in place if you install them properly. 

I advise practicing that on something else before you drill your enclosure...  Find the right size hold with the right size LED & Holder.  Trust me. 

[fogwolf]

Thanks, that clears a lot up.

Still uncertain about a couple things, though - you set the heat shrink on the leads *before* you solder the wires to the LED? Do you just leave some of each lead on the LED exposed to solder your connections right up against the heat sink? Then what about each lead from the heat shrink/joint down to the bottom? Does that part of each lead stay exposed and is it okay to cover all that with hot glue?

Thanks again.

DO NOT use your soldering iron or gun for heatshrink tubing.  Use a lighter, keeping the top of the flame about 1 inch away from the tubing.  Bring it slowly towards the tubing, but don't let the flame touch it or it will smoke & smolder something awful.  If you use your gun you'll be tempted to get it really close to the tubing, and then you may end up with nasty rubberized goop on your tip.  Blech. 

I think I use 1/8" tubing but can't remember.  Yes, you just cut off what you need.  Just remember to slip the tubing over the leads BEFORE you solder.     Yes, the bezels will hold the LEDs in place if you install them properly. 

I advise practicing that on something else before you drill your enclosure...  Find the right size hold with the right size LED & Holder.  Trust me. 

[ayayay!]

Well, let me just put it this way:  Ever tried to put heat shrink tubing on *after* you've soldered everything into place?    

You'll figure it out.  I think you're at the point where you need to try it out and see what happens.  As far as what to cover, you don't need to put anything on the LED leads as long as they're not touching anything you don't want them to.  Rat's & DODs are notorious for not insulating their LED leads.     It's all up to you man. 

[fogwolf]

Thanks. And yes, now that I think about it for a second, how on earth would I get the heat shrink on a lead *after* a wire or wires are soldered to it. Duh. Sorry, brain freezes up on me sometimes, and this is all still pretty new, so trying to soak it all in. Thanks again.

Well, let me just put it this way:  Ever tried to put heat shrink tubing on *after* you've soldered everything into place?    

You'll figure it out.  I think you're at the point where you need to try it out and see what happens.  As far as what to cover, you don't need to put anything on the LED leads as long as they're not touching anything you don't want them to.  Rat's & DODs are notorious for not insulating their LED leads.     It's all up to you man. 

[Jered]

  hehehe,...I use a cigarette for shrinking 1/16 and 1/8 shrink tube. The smoke from a lit cigarette shrinks the tubing nicely. Blehhck, nasty,...I know, I know. I hear it eeeeevvvvvery day.

[ClinchFX]

I cover both the lead and the solder joint with heatshrink, all the way to the base of the LED.  There's nothing exposed.  I use my hot air SMD reflow station to shrink the heatshrink, but I also have a small butane powered hot air gun that doesn't make a naked flame, just hot air.

I solder the wires to the LED, then I slip the heatshrink on to the wires, shrink the heatshrink and then connect the wires to the PCB.  I don't think there's anything difficult about that.  If your solder joint is neat, the heatshrink will easily slip over it.  I think you'll find that, as your soldering skills improve, and if you use a good temperature controlled iron, you will be able to solder the joint quickly enough that the heatshrink can already be on the wires, sitting maybe 6mm (1/4in) back on the insulation without shrinking.  When the joint cools, you can then slide the heatshrink down over the joint and over the LED leads, and shrink it.

My reason for heatshrinking exposed wires etc. is because it's good electrical/electronic practice.  I take pride in my workmanship.

I use the hot melt glue to hold the body of the LED in place, not the wires.

Peter.