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Jon, my DIY RCA connections have a faulty process!

192.73.8.199
Posted on March 25, 1999 at 11:24:24
Edp


 
I fully believe it to be the "craftsman"!

Since late last year, I have been building several sets of DIY interconnects, trying out different materials, but mostly because I have more components that need more interconnects.

In the last weeks I have had all kinds of odd/unrepeatable/destructive problems with these IC's. Although I somehow thought it was a heat shrink process, I have had another problem with a set that I had yet to heat shrink.

Symptoms are like loops or shorts (nasty). They tend to occur when I have just changed/removed/relocated the IC's. Gotta be the solder connections and most likely the braid portion of the IC. I think that my solder process may be melting the inner dielectric too much or something.

I gotta start at RCA/IC construction 101 again. I have read your and Thorstens DIY in the past, but boy something is real amiss.

At least I now know how much capacitor storage energy my monoblocks have. Long loud deep hums for more than 10 seconds seems like a nice reserve!

 

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Re: Jon, my DIY RCA connections have a faulty process!, posted on March 25, 1999 at 17:52:11
Jon Risch


 
Edp,

Several pointers:

any time you solder, it helps to use a heatsink on the iowre/lead. This can be a specialized clamp-on device sold forthe purpose, or it can a pair of needle-nosed piers with a rubber band around the handles, and clamped on just below the application of solder. It will wick heat away from the insulation, and also from the solder joint too, so you end up applying more heat.

Pre-tin everything, and preform the braid lead into the starting shape you need, then position and apply solder to the leads.

Teflon insulation does help, as it does not melt as readily as PE, etc.

Jon Risch

 

Re: some interesting tricks, posted on March 25, 1999 at 22:47:50
Limin Wu


 
I don't why,but people who tried said 'Yes'!

Every time when the RCA connector in soldered,storage it
in refrigerator for about 1 hours.After one hour's cooling,
use a heater gun to warm it and then fill silicon glue
into the empty space between RCA connector and cable.

Limin Wu

 

Ah ha, I think I found the common problem., posted on March 25, 1999 at 23:00:53
Edp


 
The Tara RCA plugs.

The ring portion (not the pin) is not directly attached to the stress relief/connector. There is a small amount of play, enough to make the ring loose connection to the stress relief portion. So when I either plug/unplug I could get any sort of combination of connections. By adding the heat shrink Kynar which adds a stiffness/set to the connectors so some of the connections were locked.

I took them all apart tonight and every one had the looseness, with some worse than others.

So they all got solder sweated, reterminated. Problems seem to have disappeared.

Time to find a new RCA connector source.

 

Re: some interesting tricks, posted on March 26, 1999 at 10:42:19
SFDude


 
Would filling silicon glue into a crimped joint (like I've seen in Audio Magic's Interconnects) cause any problems with the connections?

I've finally made my speaker cables out of Cat 5 wire (not Plenum unfortunately) and using crimped on gold spades on one end and WBT locking banana's on the other. I don't really want to fill the open air space inside the WBT's just yet as I may want to make another set of speaker cables using them.

 

Re: some interesting tricks, posted on March 26, 1999 at 12:01:37
Limin Wu


 
The major purpose of filling Silicon Glue is to resist
the moisture.We had tried this trick for several years
,it works fine.

Limin Wu

 

WAIT A MINUTE !!!!, posted on March 26, 1999 at 18:45:09
Sean


 
Silicone and some types of plastics can be a bad combination. Due to the acedic action of most common silicones, it can cause the plasticizers to "bleed" and change their electrical characteristics. This reduces their lifespan and also causes them to become "lossier" in most cases. This is especially true at RF frequencies, but i'm sure that it would have some measurable affect at audio freqs also.

To minimize the potential for damage, you would need to use "acid free" silicone. If the silicone your going to use smells like vinegar, it isn't acid free and WILL cause some type of reaction to take place. Sean
>

 

Re: WAIT A MINUTE !!!!, posted on March 26, 1999 at 20:39:02
Jon Risch


 
Not only that, the acetic acid (which is in all RTV silcone rubber), will also attack any metal that it contacts, and the silicone caulk itself may cause the insulationnresistance to go sdown, acting like a partial short.

Not recommended.

Jon Risch

 

Jon and Sean,Thanks!, posted on March 28, 1999 at 04:55:41
Limin Wu


 
People in Taiwan like to tried such tricks,because a
well know Chief Editor recommended it.

If putting in silicon may be dangerous,I should tell
the truth to people in Taiwan.

Thanks,Jon and Sean

 

Re: Jon and Sean,Thanks!, posted on March 28, 1999 at 05:24:39
abc


 
We use some Dow Corning RTV at work that does not use acetic acic for curing.It requires 60% humidity for 18 hours or one week at ambient room to cure.If anyone is interested I can get the part number.

 

Re: Jon and Sean,Thanks!, posted on March 28, 1999 at 11:15:53
Jon Risch


 
If you smell vinegar, it has acetic acid in it. As far as I am aware of, ANY RTV (room temperature vulcanizing) silicone rubber has the acetic acid in it. Not a lot, but enough to corrode.

I use RTV silicone rubber products at work, and have checked into them in detail, and unless they have come up with a new formula, they all have the acetic acid.

Jon Risch

 

Not all RTV is Corrosive., posted on March 28, 1999 at 11:46:09
Chris Fagas


 
Jon,

Not all RTV contains acetic acid as a curing agent. The ones that smell like vinegar clearly do. The acetic acid curing agent makes the RTV cure very fast, but as you pointed out it is not acceptable for electronics applications due to its corrosive action.

However, many varieties of RTV are made which are completely non-corrosive, as they do not contain an acidic curing agent. For example, Dow Corning 3140 RTV Coating is a "non-corrosive, flowable, room temperature curing silicone rubber". It does take 24 to 72 hours to cure completely at room temperature since it lacks an acidic curing agent. For certain rough environmental applications entire circuit boards are coated with one or more layers of such non-corrosive sealants. Many high voltage devices require the added insulation which the silicone rubber adds. Heat (per mfr spec) can be used with some varieties to accelerate the curing process.

An electronics supply house (versus a hardware store) should be able to supply appropriate RTV for electronics applications.

Kind Regards, Chris

 

silicone RTV WITHOUT acetic acid....!, posted on March 29, 1999 at 10:34:06
Dave


 
Jon - The hard fact is there are many silicone RTV products that contain NO acetic acid. Typically, they are alcohol-based rather than acetic acid based.
Check out :
Dow Corning RTV 3140 which is self-leveling,
Dow Corning RTV 3145 which is fixotropic (I'm sure I spelled that wrong)
or for a more pliable cured product at VERY low temperatures, GE RTV511 (which, although two-part, is considered RTV)
There are many silicone RTV products formulated specifically for electronics that do not contain acetic acid.
Don't be so closed-minded, Jon. This kind of information may help someday.

 

Various silicones..., posted on March 29, 1999 at 18:56:23
jj


 
Well, speaking as an old fishkeeper (none now, used to have swampwater in my well, grew great discus and tetras, now we have rock-hard city water, ewww), I know of at least 3 kinds of silicones that cure.

First are the acetic cures. They stink to high heaven, aren't food grade, and will kill fish by leeching out acetic acit.

Then there are the cyanide cures (yes, really) that also kill fish. Guess how.

Finally, there are the "food grade" silicones. Dunno what and how they cure. BUT they don't kill fish. They are also the least adhesive, and sometimes toughest to use well. Naturally!

For electrical connections, I don't think the cyanide cures would hurt. For soldier I suspect the acetic cures + leftover flux would be bad noise. If you had a mechanical connection, you'd probably make a really nice rectifier, but I doubt you WANT to.

 

Re: Not all RTV is Corrosive., posted on March 29, 1999 at 19:40:50
petew


 
this must be what EAD uses on it's upgrades of their D/A processors. I found a bunch of it sticking the "kludge" circuits onto the main board. When I called to ask about it they told me it was " just silicone"

 

Re: silicone RTV WITHOUT acetic acid....!, posted on March 30, 1999 at 18:37:29
Jon Risch


 
The last time I looked was years ago, and it was cost sensitive. Most hardware stores only stock the acetic acid curing kind, a hobbyist would probably have a hard time finding the other kinds.

The RTV silicone adhesive/sealant that is commonly available at Wal-Mart and hardware stores is the nasty kind.

Thanks to Dave and Chris for pointing out that there are alternatives.
I stand corrected.

Jon Risch

 

THIXOTROPIC !! ( I feel like an idiot ), posted on March 30, 1999 at 20:35:59
Dave


 
Wow - talk about a 'spelling' error !

I meant, of course, 'thixotropic' !

I have no explanation for this error !

Dave

 

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