How to attach an RCA connector to a chassis ? - Page 1
Forum section: electronics / beginners

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 30, 2018, 07:58:37 pm
content: I am building a pre-amp and it has 4 RCA connectors on the back. I have done some reading and it has not been helpful.Anyway here is a disassembled picture of mine in 5 pieces.I think that all 4 of the loose pieces go inside the chassis but there are a few things that dont seem to make sense to me.1 of the black washers has a lip on it as if it is meant to isolate the something from the chassis and I dont know what.What is the 3rd from left, the metal ring with a tab used for ? It looks like it is meant to be used to be able to run a wire to ground or somewhere. But isnt the whole dang assembly, with the exception of the internal signal, grounded by being in contact with the chassis ?Have you any picture that would show how this booger is attached ?Thanks.

author: Gyro
author_rank: Super Contributor
timestamp: September 30, 2018, 08:35:45 pm
content: QuoteThree of them go inside, one of the plastic washers (the one with the lip) goes outside. The lip is to center the connector so that the outer doesn't short to the chassis. The inner washer insulates the solder tag from the inside of the chassis (The solder tag goes next to the nut).If you don't need to isolate the RCA connector from the chassis, then you can just ditch the plastic washers.

author: edpalmer42
author_rank: Super Contributor
timestamp: September 30, 2018, 08:40:05 pm
content: The connector has the option of isolating the ground from the chassis or not.If you want to isolate the ground, slide the black washer with the lip over the back end of the connector with the lip pointing toward the solder end. Now push the connector through the hole in the chassis from the outside. The mounting hole has to be big enough so that the lip fits through the hole. Now add the second black washer on the inside of the chassis. The metal ring goes next, and finally, the nut. Make your connections to the solder connection on the end and on the tab.If you don't want to isolate the ground, don't use the black washers or the ring, just the connector and the nut.The question of whether to isolate the ground or not depends on your application.Ed

author: bson
author_rank: Unknown
timestamp: September 30, 2018, 08:59:56 pm
content: Drill a hole to fit the outside of the bushing lip. Insert bushing lip side in from the front. Insert the connector from the front. Add the rear bushing or plastic washer. Add the the ground tab, thread on the nut; orient the ground tab to a suitable position and hand tighten the nut with a matching socket. No gorilla stuff needed. Bend the ground tab out a little so it comes off the panel. Solder hookup wire onto center and ground tab.

author: Brumby
author_rank: Unknown
timestamp: October 01, 2018, 01:48:39 am
content: This:Quote from: Gyro on September 30, 2018, 08:35:45 pmThis is just a quick sketch showing the panel and the two washers. The important things to remember are the size of the hole - and that you need to make sure you deburr and clean off any metal bits from around the hole or you could short to the chassis.Note: These washers are only necessary when you want the body of the RCA connector isolated from the chassis. You won't need either of them if you want the body of the connector secured directly to the chassis. Which way you go will depend on the requirements.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 01, 2018, 02:41:20 am
content: This general approach is used for several kinds of connectors. BNC, banana plugs and binding posts often have the same type of optional isolation. Be sure to watch for it when repairing equipment with any type of connector in a metal chassis.

author: Brumby
author_rank: Unknown
timestamp: October 01, 2018, 05:43:55 am
content: Yes - this mounting technique is used in many places.Here's a little rework of your original photo:

author: tooki
author_rank: Super Contributor
timestamp: October 01, 2018, 09:14:01 am
content: Quote from: edpalmer42 on September 30, 2018, 08:40:05 pmWouldn't it be better to solder to the tabbeforemounting, so as to not heat the plastic washers?

author: coppercone2
author_rank: Super Contributor
timestamp: October 01, 2018, 09:20:49 am
content: RCA is shit. avoid it. maybe bnc to rca adapter.

author: tooki
author_rank: Super Contributor
timestamp: October 01, 2018, 11:30:20 am
content: Quote from: coppercone2 on October 01, 2018, 09:20:49 amThat's just stupid advice. In home audio, RCA jacks are what are used. Installing a BNC jack and then requiring the use of an adapter is just going to reduce performance and introduce points of failure.

author: Hextejas
author_rank: Frequent Contributor
timestamp: October 01, 2018, 11:44:33 am
content: Thanks folks, this is exactly what I was hoping for, with the exception of coppercone of course.

author: coppercone2
author_rank: Super Contributor
timestamp: October 01, 2018, 10:07:59 pm
content: the art of electronics has nothing nice to say about RCA connectors, for your information, they are on an avoid list, you know, just sayinmight be easier to have a sacrificial BNC to RCA adapter that can easily be replaced then to open the whole thing up.i never used them much, but I found them to be fiddly for things like CCTV. I had to adjust them every time I nudged the monitor, so I agree with the book that its a poor standard.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 01, 2018, 10:25:13 pm
content: RCA connectors are like everything else. When good ones are used within their service capabilities they are good enough for most folks. They were originally designed for audio, and then got pushed into the low bandwidth video realm (less than a couple of MHz). They were never intended for thousands of mating cycles. Their wide usage and long expired proprietary protections mean that everyone on earth has made them, for every market from the shave another 10 millicents off the cost end up through the audiophile/audiophool stuff. The stuff on the market that makes the cost manager happy and keeps the engineer one stroke from hari-kiri end of the range deserves the bad rap they often get. Particularly if assembly quality in the cables and equipment using them reflects the same attitudes.Most of the same things can be said about BNC connectors, and I can certainly tell anecdotes about flaky BNC connections.

author: coppercone2
author_rank: Super Contributor
timestamp: October 01, 2018, 10:50:22 pm
content: The so-called phono jack used inaudio equipment is a nice lesson in bad design, because theinner (signal) conductor mates before the shield (ground)when you plug it in; furthermore, the design of the con-nector is such that both shield and center conductor tend tomake poor contact. You’ve undoubtedly heard the results!53Advocates of each would probably reply “This is our most modestlypriced receptacle.”to be specific, i never noticed that much of a problem with BNC, i found even crusty old ones worked fine, but always a decent brand

author: Brumby
author_rank: Unknown
timestamp: October 02, 2018, 12:37:19 am
content: I have a couple of boxes with cables of varying types bagged up. As well as one for anything that is oddball or underrepresented, I have one for RF, one for video (D15, DVI, HDMI), one for phone, one for network and one for anything with an RCA on it. That last one is a very healthy weight.I'm sorry - but while the criticism of the RCA connector is not undeserving, advocating for the replacement of it by BNC is just elitist, absurd and dismisses the fact that the RCA is ubiquitous.

author: coppercone2
author_rank: Super Contributor
timestamp: October 02, 2018, 12:46:34 am
content: yes so thats why a sacrificial adapter is a good idea. easy and cheap to replace cable and adapter but not so easy to take the thing apart.and you can mate em so it grounds first.I also have a giant bag of RCAs, but there is no reason why you can't use a sacrificial adapter.honestly the comment was mainly triggered by someone suggesting some crazy ass shit with washers (wtf?) but its still not a bad idea if you can stand 4$ adaptersthe washer thing is nuts because real connectors come in real isolated versions, like bulkhead BNC isolated, not relying on filing holes etc to make the thing align. I just assumed RCA does not even have real isolated mounts.

author: tooki
author_rank: Super Contributor
timestamp: October 02, 2018, 01:49:30 pm
content: Quote from: coppercone2 on October 02, 2018, 12:46:34 amFFS, dude. Nobody cares about your anti-RCA crusade.1. I've never heard of an RCA jack wearing out. They're so simple, what is there to wear out?? It's not as though they have a bunch of moving parts. It's a simple friction fit.2. If you had bad experiences with them, it was almost certainly due to badcables, not bad jacks, or due to substantial corrosion, which could affect any connector.3. RCA jacks come at every conceivable price point, including ones that are inherently insulated from the enclosure. This particular model is designed to work either way. That's a deliberate design decision of this jack model, not an inherent property of RCA jacks. That you don't understand how this model is designed doesn't make it "crazy ass shit".4. They are THE standard in home audio. It doesn't matter what you think about the connector design, if you want a product that readily connects, you use RCA. It works fine for this application. The OP was not asking for opinions on what connectors to choose, and it's arrogant of you to keep belaboring the point.The only legitimate criticism of RCA jacks, IMHO, is the issue of the signal making contact before ground. But let's be realistic, in its intended application, this isn't an issue. It's not as though RCA jacks' intended uses include routine hot-plugging.

author: coppercone2
author_rank: Super Contributor
timestamp: October 02, 2018, 03:44:04 pm
content: well the design also allows you to zap the center conductor with ESD easily. especially in a shagged out audio room.same problem with the audio connectors.everyone so mad, god guys, buyers remorse from 20 years ago? everything is optical now for good reason. war's over people, japan surrendered in the 40's, no point defending this jungle anymore

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 02, 2018, 09:18:40 pm
content: This war never started, except for one person. No one here has claimed RCA phono plugs are a great design. No one is trying to force you to use them. All anyone has said is that they are adequately to purpose and widely used in audio. If you want to convert all your audio gear to BNC, no one is going to stop you. I'm not converting my TE to RCA, but I will continue to use it on my stereo gear where I have never actually encountered any of the dire outcomes which you correctly point out can happen with RCA.

author: Brumby
author_rank: Unknown
timestamp: October 03, 2018, 12:35:44 am
content: Gee whiz. Somebody hates RCAs with a passion beyond reason.In my experience, the only problems I've encountered because of the RCA plug and socket combination have been fixed by removal and reinsertion a couple of times, usually with a twist or two.

author: coppercone2
author_rank: Super Contributor
timestamp: October 03, 2018, 12:42:14 am
content: it's the cable equivalent of percussive maintenance and NES cartridges. I have seen people blow into CDROM drives because of all the chaos those things caused in the past.I am just imagining big screen tv's falling down because of bad RCA connections. I also got yelled at once because of something like that happening to me because of a RCA connector IIRC when I was young, so I have a bone to pick with them. I think a poorly placed VCR took like a 6 foot fall.

author: Brumby
author_rank: Unknown
timestamp: October 03, 2018, 01:00:23 am
content: Quote from: coppercone2 on October 03, 2018, 12:42:14 amPerhaps - but once in 10 years isn't cause for wholesale exile IMHO.QuoteNow you're just messing with us ... surely.QuoteNot sure how an RCA connector could be the cause of something like that which would not happen with, say, a BNC. But, OK - so you had a bad childhood experience and it has led you to an irrational hatred. At least we now know where it came from.

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: October 03, 2018, 05:06:59 am
content: My uncle bob was severely injured in a freak RCA connector incident, I too have not been able to move on.

author: coppercone2
author_rank: Super Contributor
timestamp: October 03, 2018, 02:01:32 pm
content: it was temperamental and I got up on a chair to mess with it and boom. Probably got nudged because you know, you need to move home AV equipment to clean the dust under it *unless your a dirty fuck*Never would have happened with BNC. Obviously people won't have it so poorly set up but the fact is the equipment needs to be moved once in a while to clean behind, under it, etc, unless its part of a sterile AV rack mount device.There is like a 100% chance some house wife is going to be regularly messing with some kind of home audio setup to find dust during regular cleaning. Maybe some people will have a filtered AV cabinet under their TV with some fan and filters to change, but I never saw that.

author: langwadt
author_rank: Super Contributor
timestamp: October 03, 2018, 02:20:21 pm
content: Quote from: tooki on October 02, 2018, 01:49:30 pmyou can get RCAs that connect ground first,http://www.neutrik.co.uk/website/uploads/images/07/660x/profi-uebersicht.jpg

author: langwadt
author_rank: Super Contributor
timestamp: October 03, 2018, 02:22:26 pm
content: Quote from: coppercone2 on October 03, 2018, 02:01:32 pmI think it is much more common that messing with the cables behind home audio is something that might happen once per decade

author: Bassman59
author_rank: Super Contributor
timestamp: October 03, 2018, 05:12:09 pm
content: Quote from: coppercone2 on October 02, 2018, 03:44:04 pmAll audio gear should use balanced connections on XLR. None of this RCA stuff. I demand that all consumer audio manufacturers switch over immediately. Also, Pin 2 hot.{waiting forever}

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 03, 2018, 06:01:41 pm
content: Quote from: coppercone2 on October 01, 2018, 10:50:22 pmWow, what great good luck you have had.I have had 10x (or perhaps 100x) as much trouble with BNC as I ever had with RCA.Yes, RCA are big, clunky, crude, etc. But that makes them much more easily repairable in the field when a million-dollar production is on the line.OTOH, I wish I had a buck for every flaky BNC connector I have had to deal with in the heat of battle.They are small, fiddly, fragile, and ill-suited for field production. But, alas, there is no reasonable substitute and virtually 100% of modern digital video gear uses them. Of course, digital video (HD-SDI) uses the 75 ohm version of BNC which makes especially the female connector extremely fragile.I try to keep "disposable/consumable" 90-degree angle fittings on my cameras, etc just to save the fragile BNC connector. But ignorant "help" doesn't know any better. Perhaps I can super-glue the disposable adapter onto the camera to protect the fragile camera BNC connector. I would be quite happy if I never had to deal with another BNC.

author: coppercone2
author_rank: Super Contributor
timestamp: October 03, 2018, 09:19:35 pm
content: What do you consider a BNC fail? The worst I had were with ancient function generators, the BNC from the 1960's or whatever looked really chowdered, but in the end they still seemed to work pretty well even when wiggled at low signal levels (I did not wanna take stuff apart).. I don't think I ever ended up replacing any of them on old test equipment I bought on ebay, though when badly tarnished and stuff I expect them to have bad HF performance in the high MHz.The only BNC problem I noticed was with no-name BNC adapters meant for computer connectors ( 10BASE2 or whatever the network standard that used BNC was). But I played with them ALOT when I was a kid.. but I just made a rule if it does not have Pamona or such written on it I throw it out. The no-name BNC splitters are HORRID, but that is to be expected IMO. But I abused the hell out of them, because they were kinda fun to mess with because they formed rotary locked joints. Also the fact that I had them as a kid meant that they were recovered from a dumpster.RCA was a completely different story, perfectly fine connectors connected to things like cameras, TV attachments would often require maintenance for no good reasonIf you want a kinda permament but not really mounting for BNC then consider using Loctite. Purple would be recommended. I tried this before with a BNC and it kinda held a bit better, but it was still easy to twist off once you gave it a bit of force, but it certainly feels stuck compared to what your used to.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 03, 2018, 09:30:31 pm
content: I consider intermittent or COMPLETE absence of the signal to be a "BNC failure".The cause is typically the female center contact deforming so that it doesn't make contact anymore.So I have to go in VERY CAREFULLY and bend the contact segments back toward the center to make contact with the male pin.My great fear is that one of these days the female center pin contacts will just snap off and I will have a completely useless $10K video camera sitting there.I am thinking of very carefully putting a piece of heat-shrink tubing over the exposed female contact to keep it from so easily deforming.But, of course that will throw off the impedance. But maybe not enough to destabilize the link.And it could interfere with mating with 50-ohm male connectors. What a mess.

author: coppercone2
author_rank: Super Contributor
timestamp: October 03, 2018, 09:33:24 pm
content: try loctiting (purple or if thats not enough blue threadlocker) on a connector to see if your comfortable with it. I bought male-female adapters for this reason to put on equipment I am using frequently. But I don't have to deal with stooges.The purple stuff is weak but it might discourage yanking.Also, if you don't give a shit, you can solder them together carefully with a powerful iron, but the thing might melt, and you need to use an agressive flux.From experience soldering them (to make sealed connections in really ghetto enclosures) you need alot of heat and fast or the plastic heats up and expands and destroys the connector or gets burned and the impedance probobly changes).The little gasket will probably be destroyed though, but thats only effecting the one commonly not attached to equipment with moving parts. By destroyed I mean it suddenly requires massive pressure to turn but still works fine. They have the dielectric (teflon I think) in a slug around the middle, but some have like a rubber o-ring under the rotatable part that tends to get destroyed. But, I think if you had like a 150W soldering gun, you might be able to do it, with agressive flux, so it does not damage anything, if you tin a spot on both, cool them completely, then bridge the tinned areas when their mated.A less nice solution would just be to get thin steel wire, or maybe piano/painting wire, wrap the mated connection fairly tight, then seal the wire with a crimp/ferrule so it stays tight after you twist it together on the end, then just give it a trim. This way someone would need (decent) wire cutters to undo it to remove the sacrificial connector. If someone knows their tools they might be discouraged from using their field kit to cut steel wire, unless they have nice carbide cutters etc.

author: tooki
author_rank: Super Contributor
timestamp: October 03, 2018, 11:34:59 pm
content: You’re just trolling us now, right? It has to be trolling. Cuz it’s either that or the ramblings of a lunatic.

author: coppercone2
author_rank: Super Contributor
timestamp: October 04, 2018, 01:28:25 am
content: NOTE: This message has been deleted by the forum moderator Simon for being against the forum rules and/or at the discretion of the moderator as being in the best interests of the forum community and the nature of the thread.If you believe this to be in error, please contact the moderator involved.An optional additional explanation is:

author: Cerebus
author_rank: Super Contributor
timestamp: October 04, 2018, 01:46:12 am
content: Quote from: tooki on October 03, 2018, 11:34:59 pmQuote from: coppercone2 on October 04, 2018, 01:28:25 amA rude lunatic then, glad that's sorted.

author: jh15
author_rank: Frequent Contributor
timestamp: October 04, 2018, 04:30:00 am
content: I agree the RCA is ok for home consumers. It has a 'how you doin' impedance for rf.BNC failures come from video people a lot due to the different dimensions of 50 and 75 ohm connectors.They may borrow cables from a bench instrument and plug into a pro monitor or verse visa.I like hermaphrodite connectors such as on my GenRad stuff and Anderson powerpoles (for power, not impedance.)

author: Simon
author_rank: Unknown
timestamp: October 04, 2018, 10:31:09 am
content: Quote from: coppercone2 on October 04, 2018, 01:28:25 amWhy don't you calm down before you get banned?

author: bd139
author_rank: Super Contributor
timestamp: October 04, 2018, 11:38:39 am
content: Wow this thread turned to shit didn't it.I occasionally use RCA for RF when I run out of BNCs and want to do something *right now*. They work fine up to 20W or so and under 30MHz with no measurable reflection (RL no different to straight termination) or heating. My portable linked dipole also has the links done with RCA inline connectors. Absolutely fine so far. Even used them for power on occasion. Yellow ones for power. Black ones for RF. Red ones for audio. It doesn't matter if you stick the wrong things in the wrong holes either because there's a DC block on all the audio and RF holes.Have I've given everyone cancer with that admission?I rarely get any problems with any connectors because I don't buy crap ones, I look after them, replace them when they are worn out and I terminate them correctly. That's the winning combo.

author: Cerebus
author_rank: Super Contributor
timestamp: October 04, 2018, 01:34:54 pm
content: Quote from: bd139 on October 04, 2018, 11:38:39 amPossibly, but you're the kind of bloke who thinks that a BLU-82 "Daisy Cutter" is "less bovver than an hover " and thatRedi-mixis a lawn treatment, so we've learned to filter your advice.

author: bd139
author_rank: Super Contributor
timestamp: October 04, 2018, 01:44:42 pm
content: I'm only concerned with getting from A-B not who gets in the way while I'm getting there

author: CJay
author_rank: Super Contributor
timestamp: October 04, 2018, 02:12:17 pm
content: Quote from: RobertHolcombe on October 03, 2018, 05:06:59 amI had a really bad experience with an RCA connector in 'nam*, there was a murder** and a mass brawl****Tottenham, it was a mobile DJ set.** On the dancefloor*** Everyone**** was KungFu fighting.**** Surely not 'Everyone'?

author: macboy
author_rank: Super Contributor
timestamp: October 05, 2018, 05:59:46 pm
content: Quote from: jh15 on October 04, 2018, 04:30:00 am75 and 50 ohm BNC are entirely safe to inter-mate because all contact dimensions are identical. The 75 ohm version simply does not have the dielectric within the mating area, which increases the impedance. The N type RF connectors do have different dimensions in the mating contacts and will be damaged by inter-mating. Many people assume the same for BNC, but it is not true.I copied the following two sets of diagrams from one of Amphenol's spec sheets.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 05, 2018, 06:27:42 pm
content: Yes the common 50-ohm BNC connectors are mechanically interconnectable with the (more rare) 75-ohm version.As @macboy says, the problem is that the center contact of the female 75-ohm BNC is essentially unsupported (without any dielectric mechanical support) and that makes it extremely vulnerable to any but the most careful connection. I have lost count of how many times a camera feed goes dead just before the program starts because some female 75-ohm BNC connector has gone intermittent because of deformed center-contact pin. Typically on the camera output or the switcher input.

author: jh15
author_rank: Frequent Contributor
timestamp: October 07, 2018, 04:37:32 am
content: I stand corrected about the conductor dimensions.I learned during ISF training that 75 and 50 ohm bnc connectors do not play nicely with gorillas or stage hands.Now I need to know about n connector interfacing dimensions that I recently forgot. What's the story there? Something about the pin. I am worried not to damage my antenna analyzer.,

author: CJay
author_rank: Super Contributor
timestamp: October 07, 2018, 08:56:32 am
content: Quote from: jh15 on October 07, 2018, 04:37:32 amPin diameter of a 75R N connector is, I think, smaller than a 50R pin

author: langwadt
author_rank: Super Contributor
timestamp: October 07, 2018, 03:06:34 pm
content: Quote from: Richard Crowley on October 05, 2018, 06:27:42 pmI seems to remember reading that the 75 and 50 ohm BNCs became compatible by some standard that came out in the 70's,the story that they aren't just keeps popping up