I am on my second pair of crossovers for my Polk SR6500 car audio speaker set (a 6.5" mid driver and 7/8" ring radiator type tweeter per channel).
The first set was stolen along with other gear, a high speed chase occurred (ie lots of police), the criminal rolled the also stolen vehicle (but it wasn't mine thankfully), and my xovers were tossed about.
I did get them back. They functioned OK for about three months and then one started cutting out the tweeter intermittently and then the other one did too. This was likely a circuit board trace crack issue but that is not my concern at the moment as I do not intend to allow a theft to happen again.
I thought the true story would be interesting and fun to visualize as the convict did some barrel rolls, is in prison, and will be there for quite a while.
Anyway, I want to correct a problem with the crossover design and it is that the air core copper inductors will release from the circuit board (ie the bonding agent, whatever it is, fails after time).
So, as a frequent DIY home auto mechanic also, I was wondering if applying a bead of clear RTV where the copper inductor meets the circuit board would be OK? Most certainly, the RTV can handle the temperatures, heh (-75F to 400F). And, it will bond securely (I use the stuff for tons of difficult to "stick together" substances).
Lookup Permatex product #80050. The link is: Sealants : Permatex® Clear RTV Silicone Adhesive Sealant.
Let me know what you experts think. I attached a photo of what the xover looks like. Each xover has two air core inductors that I would like to fully lock down.
Thanks!
The first set was stolen along with other gear, a high speed chase occurred (ie lots of police), the criminal rolled the also stolen vehicle (but it wasn't mine thankfully), and my xovers were tossed about.
I did get them back. They functioned OK for about three months and then one started cutting out the tweeter intermittently and then the other one did too. This was likely a circuit board trace crack issue but that is not my concern at the moment as I do not intend to allow a theft to happen again.
I thought the true story would be interesting and fun to visualize as the convict did some barrel rolls, is in prison, and will be there for quite a while.
Anyway, I want to correct a problem with the crossover design and it is that the air core copper inductors will release from the circuit board (ie the bonding agent, whatever it is, fails after time).
So, as a frequent DIY home auto mechanic also, I was wondering if applying a bead of clear RTV where the copper inductor meets the circuit board would be OK? Most certainly, the RTV can handle the temperatures, heh (-75F to 400F). And, it will bond securely (I use the stuff for tons of difficult to "stick together" substances).
Lookup Permatex product #80050. The link is: Sealants : Permatex® Clear RTV Silicone Adhesive Sealant.
Let me know what you experts think. I attached a photo of what the xover looks like. Each xover has two air core inductors that I would like to fully lock down.
Thanks!
Attachments
Thanks for the info.
I know the stuff you are talking about but do not have any on-hand. I do like to keep my garage stocked with just about everything but cannot think of an easily defensible reason for buying some, heh. "It is for the lug nuts so they won't fall off the car!"
I assume that by not objecting or warning to my use of RTV, RTV will work also?
Thanks again!
Make sure you use a neutral cure RTV. Some of the more commonly used versions have a highly acidic cure, ie they give off acid fumes in the curing process. You will find this very corrosive to copper. Need to find the ones specifically intended for electronics assembly.
Same can be said for 2 part epoxy resins as well - similar cure phenomena.
Same can be said for 2 part epoxy resins as well - similar cure phenomena.
That one is of the acetic variety, it is not suitable. You should use a neutral one (alkoxy or methoxy)
AHA! Excellent information (actually a warning, heh).
Yes, the RTV I use does strongly smell like vinegar (acetic acid) until it fully cures (around 24 hours). So, that is a "no go" and I now understand why. Thanks Johno! Someone else checked out my link to the Permatex RTV product and said that it was a "not-to-use" and I greatly appreciate that. Thanks Elvee and all other respondents too!
I will try and locate a product "specifically intended for electronics assembly" as recommended. Google "neutral cure RTV" to start.
In the meantime...
Any recommendations on a brand/"model" of safe-to-use glue/epoxy before I start digging around the internet and get to the point where a radio shack kid says, "naw, this stuff will work great" (without really knowing). No offense to RS but I've been told some pretty contradictory stuff in the past.
What have the experts here (all the people other than ME) found as a "non-acidic" adhesive?
I do have a hot glue gun and the "sticks" are this white translucent kind which is likely similar to ALL of the different sticks, right? I've only ever had this kind glue for this gun during all of these past years (heh). Well, the problem I've run into using this glue gun and the "sticks" is that the glue will stick (bind the surfaces) but it doesn't take much pressure (a fingernail only) to separate the glue bead from what it is supposed to be bonding... My experience anyway. Other than that, I love the hot glue gun idea!
It is very unlikely that I will be able to get yet another new set of these xovers because Polk stopped production of their model SR6500 a few years ago unfortunately and I really like their smooth sound.
So, I'd like to lock down the inductors, heh.
Also, on a different topic but perhaps within the same discussion group:
Does anyone offer a service (even a private home/garage service) where I could send to them one of my "old" xovers for expert analysis which would be the identification/measurement of all components and the creation of a trace schematic so IF these two fail, I could know the specs in order to build a couple? I do not have the know how or equipment to do so. The resistors and caps are labeled but the inductors, "glow fuse," and other items are not and measuring those, from what I have read, is beyond my capability... I do wish I knew how to as it would be fun.
I greatly appreciate all of the help on this. Thanks all.
The fact that he's gluing enamel not copper might make this a moot point?
I'm with the glue gun gang, never had a problem. Almost zero set-up time.
Very nice! Thanks for the info. Looks to be under £100 in cost too!
I am all about learning this stuff and a device that can measure components (such as inductor coils) which is fairly cheap in cost but yet accurate is a huge score for me.
Or, like I said, I would gladly "outsource" this project to a trained specialist. I respect electrical engineers quite a bit.
Thanks.
The fact that he's gluing enamel not copper might make this a moot point?
I'm with the glue gun gang, never had a problem. Almost zero set-up time.
I'm lost (ignorant) with regard to your post. Gluing enamel and not copper? I admittedly do not get the point...
The inductor coils are copper and the circuit board is a black color (perhaps painted?).
Just trying to understand better.
BTW, if all here think that these xovers are WAY too "prettily built," you are right! I would have been satisfied if Polk had made these xovers on a pine wood board (but with close tolerance components of course).
The massive and heavy heatsinks of these xovers have never ever been used and that is after hours of 125Wrms moving through each of them. I honestly do not know how I could heat them up using music material.
Thanks!
Excellent value for the money
Handheld Capacitance Inductance L/C Meter LCR LC200A Multimeter Electric Bridge | eBay
Handheld Capacitance Inductance L/C Meter LCR LC200A Multimeter Electric Bridge | eBay
I think what he implies is that the inductor coils are copper, but enamel coated for insulation resistance. This prevents the turns from coming in electrical contact with each other. So although it might look like you are gluing copper to the board, you are actually gluing the enamel coating which thinly covers the copper.
p audio
if you goop your crossover coils with the stuff your considering you may end up with shorted or partially shorted turns in these inductors the corrosive nature of the rtv as it cures also leaves behind resistive crap.your x-over will work but probably not at the right frequency.
i'd do a visual inspection of the solder joints on the board
with a tweeter cutting out i'd check capacitors
if you goop your crossover coils with the stuff your considering you may end up with shorted or partially shorted turns in these inductors the corrosive nature of the rtv as it cures also leaves behind resistive crap.your x-over will work but probably not at the right frequency.
i'd do a visual inspection of the solder joints on the board
with a tweeter cutting out i'd check capacitors
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Aha. You have educated an ignorant one! Thank you!
I always wondered HOW the copper windings did not just create a "full electrical connection point-to-point." A very thin layer of clear enamel, eh? I always assumed that something like that must be going on (otherwise, the windings would not be necessary) but thought, NO WAY can a thin layer of anything separate the power/wattage from each adjacent winding. I was quite wrong, heh.
From what the very helpful others have posted, would the following products work A-OK? I did contact my local Radio Shack and the person did know about "neutral cure" silicone for electronics but the store didn't carry it.
So, here is what I found which is local to me in Minneapolis:
American Chemical:
Product AC-11601
Type: Aluminum
Solution: AC-11600 series RTV Acetoxy Silicone is a high quality, single-component, 100% silicone sealant which contains no solvents or fillers. Perfect for exterior and interior sealing and caulking. It adheres to metal, glass, marble, tile, ceramic, porcelain, painted surfaces, non-oily woods, plastic, and rubber. It can be used as an adhesive for bonding surfaces together. Colors: Aluminum, Black, Blue, Bronze, Clear, White, and Almond. 10.3 oz cartridges.
Product: AC-970 Series
Type: Multiple Colors
Solution: AC-970 Series Silicone is a strong, high-performance, neutral cure, 100% RTV silicone sealant. This formulation offers impressive unprimed adhesion with a wide range of materials. The unique non-acetic chemistry will not corrode or react with common building materials and most I.G. units. Tack-free in 15 minutes and cures fast without any strong, offensive odor. Cured sealant stays rubbery from -40°F (-40°C) to 250° (121°C) and is virtually unaffected by sunlight, ozone and weather or temperature extremes.
This link will take you to the above information:
Silicone Glue, Silicone Adhesives, Flexible Silicone
Please do let me know what you experts think. I'm leaning towards the AC-970 because it makes mention of temperature ranges and in Minnesota, -40F is not unheard of (unfortunately).
Thanks again!
BTW, I did find the only glue that I've ever used in the glue gun. It is called "Crafty Magic Melt General Purpose Glue" and is in a 25 pack of oval sticks. But, like I said a while back, the stuff can be easily "popped-off" from whatever surface it is trying to adhere to so I'd like to use the no-acid silicone.
p audio
have you finished removing the crossovers and inspected the board for bad solders?
i might be making an assumption but are you trying to glue the coil to resolve a problem like cutting out or popping audio? as a service tech i've seen many an easy repair made impossible with the liberal application of all kinds of stuff epoxy, silicone,crazy glue...
you may want to explore more serviceable solutions like cable ties to hold the coils to the board...
in as far as glue guns the high temp industrial grad glues are safe(as in they won't hurt your enameled wire coils)but watch out for the tip it does get hot enough to damage enameled wire!(personal experience!!)
have you finished removing the crossovers and inspected the board for bad solders?
i might be making an assumption but are you trying to glue the coil to resolve a problem like cutting out or popping audio? as a service tech i've seen many an easy repair made impossible with the liberal application of all kinds of stuff epoxy, silicone,crazy glue...
you may want to explore more serviceable solutions like cable ties to hold the coils to the board...
in as far as glue guns the high temp industrial grad glues are safe(as in they won't hurt your enameled wire coils)but watch out for the tip it does get hot enough to damage enameled wire!(personal experience!!)
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