They looks like they're yellow chrome plated. I used to send stuff for yellow chrome plating if the customer wanted to powder coat the object and they wanted some rust protection on it. It's really hard to get a good finish when powder coating zinc plated stuff. One customer used to buy hot zinc plated sheet metal cheaply that were rejects from Volvo Trucks production line. Hot zinc plated sheet metal can emit hydrogen gas when heated.
You're probably right. I bet they're zinc plate and chromate passivate. Even worse, I wouldn't put it past them to have used hexavalent chrome, which is nasty stuff and has been banned. Want to know how bad? Watch the Film 'Erin Brockovich'.
Its a high-risk carcinogen. There are heavy restrictions on it. I had to change the finish specs on a lot of automotive parts because finishing subcontractors stopped using it.
I don't recall ever having problems with the solid type banana plugs. The rotating ones have given me nothing but problems unless I buy expensive ones. I usually solder them so they don't rotate, then they work fine.
Which Side did you solder that worked the best for you the tip? or the other end? I like the how tight the barrel connects is & is a lot BETTER than most!!
That is what I was thinking for fixing my cheap eBay banana plugs for my speakers... As soon as I attached them I could hear dodgy connection going on... EDIT: Uggpff, I give up on that; melted it, I'm not good at soldering lol. EDIT: I got a grip and remembered I could take the plastic bits off - soldering ain't pretty but they are much better now, no dodgy connection noises.
AS I'm about to buy a kit for 50 bucks (USD) that includes banana plugs as a design improvement feature. I HAD to watch it all. And now I may build my own kit-despite the additional expense.
I think they're supposed to extend lengthways when compressed, and make contact at the ends? Those seemed to have a LOT more vertical play on the shaft compared to the genuine probemaster ones
This. It seems to be a clear example of whoever made the dies and set up the machine having no understanding of how these type of connectors are meant to work. Played with these awful ones and also some good ones. They both start out slightly loose and the moment they are in the socket, they tighten up a lot and don't 'spin' where the crappy ones still do. The super cheap 'gold' doesn't help much either. :)
I learned this lesson when I was younger, I was using banana plugs for my speakers (they have the Screw/banana socket type) - after a while I started to get crackles and all sorts, re-wiring them (using same plugs, thinking "no way it can be them") trying a different amp / input etc... nothing resolved it, except I noticed (purely by accident) that when I moved/span the plug with the amp on, it crackled - so I cleaned the contact and the plugs, and still no difference, so I ended up swapping out the plugs and it was fine again... it did the same thing again eventually, so I gave up and now just use the screw terminal connection instead, not as easy when connecting/disconnecting but I haven't had an issue since...
Soldering one end can make them fit very tight in jacks and the surface finish on these are quite terrible to begin with. Wouldn't want to wear out the jacks on an expensive piece of gear with them.
Which Side did you solder that worked the best for you the tip? or the other end? I like the how tight the barrel connects is & is a lot BETTER than most!!
@@simontay4851 Which Side did you solder that worked the best for you the tip? or the other end? I like the how tight the barrel connects is & is a lot BETTER than most!!
Ashley Sommer I agree in principle; but would it really have been as effective if it were cut down to 1/5 its length? Rapid-fire really isn't Dave's style. He rambles, yes; but many viewers (myself included) enjoy the sheer entertainment value in Dave's "just look at how completely and utterly shitty this steaming pile of turd is" videos.
Thanks for this. Most people never consider these things as a source of problems. Years ago I had a terminal strip where the hard black plastic had turned semiconductor from the cleaning sprays used. Took a while to isolate that one.
Thank you so much! I've rarely suspected banana plug contacts when I troubleshoot problems on the test bench! Now I'll add it to my checklist! Moral of the story: When your banana plugs get too tainted/corroded, check for reliability and replace if necessary!
the secondly shown multi contact plugs - LS 4 - are really high grade. Got them on stock and in use for > 25 years, practically no wear-off. of course also no corrosion. 0.02 ohm for a 50cm mc cable. You get what you pay for.
Because I don't have expensive stuff I know this problem since... childhood. I did solder always one loose end to the center rod and no long crying. It supports high current too.
This shit is also used on some cheap motor ESC units for drones. These can be carrying as much as 40amps at full power! Check your connectors and if the contact part rotates either solder them or best throw them away and get top quality plugs. The quality plugs have the contact barrel crimped to the center core for a perfect contact.
Cadmium dichromate over steel would be cheapest, and goldish color, but really inappropriate for any kind of precision electrical contact. Growing up my family had an electronic connector manufacturing business, and saw lots of beautiful gold plated coax connector parts, and parts like mechanical brackets with cadmium dichromate.
After watching your video, I checked my leads that have these rotating barrels. Most were OK but a few showed resistances of as much as 3 ohms! Almost all showed changes as the plugs were wiggled. One even went momentarily open! Easy fix for them though. I just soldered the tip end of the rotating barrel to the plug. The gold ones soldered easily. The nickel plated ones needed some light scraping first. On all of them, while the solder was still molten, I slid the barrel all the way to the tip. This allows space at the top of the barrel to allow it move in an out as the leaf springs are compressed and prevents jamming or overstress of the springs. All of my leads now measure 20 milliohms or less and the wiggling issue is gone.
Gold plating is less important than tight tolerance when it comes to rotating banana plugs. There's too much play between the rotating part and the plug's core. The rotating part is designed to longitudinally "stretch" when plugged in and apply longitudinal pressure on the core to maintain good electrical contact. If the contact pressure between the rotating part and the "core" of the plug is insufficient, you will get bad contact impedance/resistance even if both are made of pure gold.
As an alternative to scrapping those plugs, of which I have several, I'm going to try carefully soldering each end of the "cage"to the body in the hope of improving the contact resistance.
What's interesting is what happens at 12:25 there's a small drift that seems to zero out over time, my guess is that when you moved the contacts up and down you esensially heated them up by friction and changed their resistance.
I don't think the issue is so much the "split" as it is the diameter of the bad connectors. You can see the rotating bit does not have the same diameter at the ends of the rotating piece as the ends of the solid piece, and overall next to the Probemaster connectors the entire thing of the bad connectors looks like the diameter is smaller.
Isn't that what is called a "fool's gold"? I believe I've seen a list of about 20-25 different coatings that look just like gold. And many of those coatings are not conductive at all.
I got some with the same problem, and I improved it drastically by dumping a bunch of solder into the joint where it rotates. It still rotates, and it fills up the space and fixes the fit. I can go from "total crap" leads up to "cheap but works."
The cheap one is Tin casting body with possibly steel spring and gold plating just thick enough to optically look gold coloured . The good one is turned brass with brass spring and proper thickness gold plating.
are you sure it is the ring not compressing because of the lack of the split in the ring, but rather that the length of the rotating sleeve is too short for the recess on the pin. Seems to me that when compressed the sleeve will lengthen first till it comes into contact with the end stops and at that point the curves will start to deform along the long axis before any forces are high enough to start compressing the end rings diametrically.
The real problem is that , the spring sleeve should compress around the inner solid part of the plug . To do this it needs an small air-gap between the sleeve edges , now it is rotating so freely , that it won't though the inner solid part even if inserted in a socket . It is possibly made to the wrong diameter tolerances , and crappy '' gold '' plating as well !
I discovered the same problem myself when I built extended leads for an RTD calibrator. I doubt I would have ever noticed it otherwise. The simple solution is just to apply a dab of solder right at the contact tip, so the spring part can't rotate and is locked in place. Haven't had a problem since.
Yes, I believe you are correct. Plating is not the problem here. Mechanical design is. The split is too narrow, so the sleeve will not pinch the center pin when the plug is inserted. I have a hundred of them, but mine are even worse: The sleeve ends are dovetailed together, so there is no split at all. A quick slice with a Dremel style cutting disc will fix them.
I agree. Early in the video the split on the rotating barrel can be seen to be much thinner than on the Probemaster plug. The narrow split will close and not allow significant contact pressure with the core of the plug, when inserted into the socket. This must contribute to the problem.
Yes I bet this is the main problem. Since the cage is so loose on the shaft, the split needs to be even bigger. Try cutting away at least a millimeter and see what happens.
Good on ya for spending the time to make this video. Younger electricians like me don't even look for crap like this sometimes, but the second I saw how it worked it makes sense.. Good knowledge is worth the time to educate.
I have lost a lot of time from using low-quality banana plugs and test leads. (Worst was some alligator clip leads which used super thin wire and was only crimped, not soldered, sometimes without the copper even touching the clips). Nowadays I am a lot more careful what I buy.
I've had similar problems with some old tin plated banana jacks. I move the rotating part as close to the tip as possible then add a nice dab of solder on the tip end of the rotating contact point, so it's still springy. Sure it doesn't rotate anymore but the connection is solid.
I've run into banana plugs like this quite a bit. When I do I always solder the rotating part to the shaft, that usually takes care of it. The problem with the cheap ones usually is the manufacturing tolerances are too loose, which does not allow the rotating piece to grip the shaft when inserted into a jack.
A tip I got from a mate, Nigel, at The Chord Company (who make high quality interconnects and cables), which was to use the high power, clamping, soldering iron from RS. This is especially useful if you are making up speaker cables with a cross section > 2.5mm sq. There's enough thermal capacity to get the whole job done before it starts significantly heating the plug (or melting the plastic on the cable). It's a helluva lot quicker. The soldering iron is only about £50 at RS.
As the rotating flanges are compressed by the socket they elongate. That elongation pushes the ends of the flanges against the ends of the shaft indent. The loose flange with bent ends doesn't make a good contact with the ends of the shaft indent. You can see how all the others have much smaller gaps at the end of the flange, except the Farnell one, and that has a much more curved flange that would elongate more so needs that larger gap. It's that elongation pressing against the ends of the shaft indent that makes the major electrical contact, not the contract around the shaft (although that does play a part).
Possibly the manufacturer didn't use a nickel under-layer between the gold and the brass/BeCu or whatever underneath. Just plating gold directly over copper causes the gold to start diffusing into the copper and might cause pitting like that, so typically one has to add a layer of nickel plating between the copper and the gold to prevent diffusion.
I always use high quality 4mm banana plugs from hobbyking, they're for RC planes, to be loaded with like 50A and $1000 plane's "life" depends on them, you can't really get better ones. + add their silicone wires and you have AAA quality cables.
You are dead right they are excellent quality, plated brass. You can get these with hermaphrodite shells which can be made up to regular plugs & sockets. Also I join them together back to back which gives me a plug with extension socket to loop into other test gear.
I do the same. I've been using connectors from hobbyking for my octorotor (with camera gear its about £6000 worth) and they are spot on although they are massive ones on that with a built in capacitor in the tip to stop arcing on connection. I made my own leads in the same way as you except I added some of their wiring loom mesh with adhesive lined heat shrink on each end. I use them a lot on site for domestic electrical testing as the mesh protects them from splitting the silicone on a stray nail!
Some of them (not from HK) are so bad that they don't even stay in the female sockets. The guys on RCGroups are recommending the ones from HeadsUpRC and Aloft. www.rcgroups.com/forums/showpost.php?p=38832952&postcount=9953
Me too, allways replace crappy hard pvc cables on crocodile clips, multimeter probes... etc. with silicone insulated thin coper fiber soft cables from hobby/RC shop, they come in all diameters, from "hair-like" to "welder wire" diameter... It gets down below -20 deg.Celsius here (cr123a 3V lithium batteries in multimeters instead of 2*aa or 2*aaa save the day)... try using pvc insulation at that temp ;-)
I've run in to this issue before. It is the split in the expanded sleeve. I've had to pull them off and take a dremel tool and increase the gap in the sleeve. When you insert the cheap bananas the sleeve makes great contact with the jack, but the split closes before the sleeve is compressed onto the inner pin. This leaves the connection loose.
What's really the point of the sleeves being rotatable anyway? If one wants to rotate the plug while inserted the outer slits can just as well slide along the inner wall of the female plug anyway, just as with the solid kind of plugs. The main reason for the sleeves I guess is not its ability to rotate, but rather to permit the entire outer part to expand lengthwise when the slits acts as springs being compressed. Therefore they need only have a loose contact at one end, while the other ought to be soldered or crimped in place to ensure good and permanent electrical contact. One less point of failure! Good video to raise awareness of the potential issue though, although I tend to agree with those that point out it could well have been shorter.
I never use the rotating here in New Orleans area the humidity destroys them. All gold plate wears off eventually. This is the first time I have ever disagreed with your sage advice. I actually solder them up where they don't rotate, measure them and no issues l.
I've seen this before. The diameter of the inner pin was too small, even when the plugs were inserted they could still rotate freely. A decent banana plug should not move at all obviously. I 'fixed' it by soldering one end of the spring to the pin inside it. Looks ugly but it works.
With those plugs, I have used them, but I solder the tips (see the tip and where the fold joins 5:08) and then it does not rotate, but the springiness still does the job. It works! But if the gold plating is bad, then not much chop, throw them out.
I ran into a set that the flang didn't expand when or had bad contact when it was inserted into the female banana side. I quick work around since resistance was not a big deal for what i needed the cable for anyway, I just dropped some solder so they made contact and wouldn't spin anymore.
It is not just the 'gold plating' issues here.. like everything else, it is more complicated. The compression gap on the crap connectors is too small. When compressed, it forms a solid ring with a diameter larger then the inside solid piece. That is the major design flaw.. a flaw shared, I might add, by the connectors you sell. The problem is more apparent in the tarnished ones, but yours appear to have the same crappy contact patch, theirs just combines that with tarnish.
Unfortunately I've purchased a few as well. I ended up holding the rotating part close to the tip and soldered the tip creating an electrical bond eliminating the rotation yet allowing to compress and move on the wire side. Hope this helps others who have in the bin!
I'm with Dave here. I've got access to a mini lathe and some pure copper rod C101. It is the best electrically but not so good for machining which is why tellurium copper C109 is what any manufacturer would choose. Then gold or tin plate. I have more than enough time to run the lathe slow for C101. I've had loads of shit banana plugs from China, and can't afford/justify Pomona, so I will make my own ;)
Drew Dastardly The traditional material for quality contacts is brass, no plating, just solid brass. Color would be about the same, surface tarnishing should be slower.
Yes, pure copper machines poorly. On the other hand, I've seen materials machined, like C60 hardness tool steel (like a milling cutter), with the right cutter (carbide) and feeds, that I never would have imagined it possible. You might try some free cutting brass, alloy C360. These long thin connector parts are generally made on automatic screw machines, in free cutting brass, which machines really nice.
I bought the same crap plugs on eBay for putting on some wires. I got around this nonsense by just soldering the rotating part to the shaft part with a huge blob of solder. I was seeing disconnects due to the stupid plugs!
It struck me right away, no split to transfer the compression force to the connection and probably too spaced between the nose button and the rear collar, such that after compression the spinning splayed part never presses it to the nose & rear. I'll never buy those spinning type again. Can't believe this is the 1st time I bothered to think that through.
you can see at 4:24 there aint any leverage on the carussel-springs, while on the propemaster there is equal dimension and some leverage so they can fall in under the pressure and do as intended..(bad or wrong dimension on the carussel.)
Yes as you said the rings don't have a gap. Very tarnished and pitted, looks like the new special metal now being used, known as "ElCheapolina metal :-)
I had some of these and they caused a bad problem. After only a couple of uses they began to break up and bits of the springs fell into my equipment. The rest of the plugs rapidly ended up in the bin.
Couldn't you just flow a little solder in there to solder the 'peel' to the 'banana' part? If you heat the peel up and flow it in the edge there it might get wicked in. For that shunt, they don't need to rotate so it should work.
some things one should not cheap out on. wire. connectors. thermal paste. flux. you spend more, yes. but you also then have a product that is supported by a known manufacturer and will actually make you want to use it more.
i have a problem with doing anything rigid like this with those connectors ... the slack of wires tends to help but i have never understood these things anyway it might help if you just hit the ends of the floating part with a crimper a little bit just to make them more grippy
I would not say that the high resistance is entirely related to the loose end rings and the quality of the plating. I believe that the length of the splayed contact part will increase when the banana is inserted in the jack (due to its mechanical design). This causes the end rings to form a secure contact with the “hard stops” of the inner shaft. For sure, the splayed contact part is very short in length when compared to the overall length between the “hard stops” of the inner shaft, which may be the cause of the intermitting contact/high resistance.
The problem is not only with the gold-plated banan plugs, and it is not only due to poor plating. I bought 20 nickel plated contacts whose surface looks very good. All must be eliminated due to high contact resistance. This is because the spring sleeve is not tight enough when connected. Test by connecting only one contact. If it is simple to rotate it with minimal force, it should go to the trash.
The rotating part is supposed to expand axially once compressed into a socket. This is supposed to make them bond on the lower/upper circular surface. When you compare proper to the dodgy ones you can feel the slight axial freedom. I had a bunch of otherwise proper silicone wires and decided to use a crimping tool to permanently “fix” the two parts. That improved the issue quite a bit. But I found the crimping losses its power over use. I should solder them in place ...
The "rotating skirt" design might look cool, whether gold-plated or not, HOWEVER.... it has one major flaw: it does not give a snag and tight connection. That's why the ohm meter jumps all over the place when you wiggle or rotate the plug. The problem is the rotating skirt very loosely touching the core of the plug. If you plug in the banana in its socket and can easily spin the plug around, your connection will be intermittent. SOLUTION: solder one end of the skirt to the shaft to prevent it from spinning completely.
This is a Great way to test them , Their are so many that have a very loose fits , These one do not,,, but failed the test ,,Thank may my testing begin w this test! Thanks
I bought these crappy plugs a year ago on ebay and recognized the same problem right away. I tried to solder the turning part to the inner - that mostly solves the problem but the plugs become more difficult to fit in. I also recognized the "gold"-plating is only golden color - no quality at all unfortunately! You really get what you pay on those chinese ebay shops...
I use Mueller or Pomona connectors exclusively and have never had a problem. I've been wondering if paying extra for those has been worth it and this video confirms that it is!
Pomona makes great plugs, cables and connectors. I purchased my collection in the 70's and to date only one banana plug has failed. I've used them at home and job (Laboratory and repair). I've tested and use them reliably up to 10 amps where they get warm. Expensive but well worth the money.
It seems like as you moved the solid probes the connections warmed up a bit and the resistance increased. Then things went back to zero when you left them alone for a while.
Some of the effect you were seeing on the better quality ones may have been due to heating of the plug from your fingers when you twisted them (thermocouple). You can see how the offset settles back to zero after you stop handling them.
Same thought Jerry: also possible some very localized heating from friction as Dave twisted the plug around. You can see as he stopped twisting and continued to talk the resistance started to drop (as they cooled?). Cheers, Mark ************************
The problem here is the ends of the banana plugs not be able to compress against the shoulders due to the excessive clearance. As a result, there is no solid connection between the banana section and the rod.
Put them upsidedown on the bench and tap the bottom (hard) with a hammer. The longitudinal gap between the shaft and the flex is too large. Try and shrink it slightly.
The corrosion on the cheap plugs looks like it may be concentrated in areas where your fingers would touch them. I wonder if it is related to skin oils or salts. I also think that the rotating contacts are supposed to elongate when compressed by being inserted into a jack and I think it is this elongation which makes a reliable contact by jamming the ends of the rotating part against the stops on the stationary solid part. This also requires that the rotating piece be truly springy which would require a special alloy like tellurium copper.
Not only banana plugs, but BNC - RCA adaptors. I bought a packet of four from e-Bay and one of them came apart when removing it from my FeelTech S3200 Dual Channel signal generator! I had to glue it up with CA glue.
There seems to be a lot of up/down movement on the rotating contacts of the crap plugs compared to all the others. When the curved splines compress it should also elongate - pressing the ends against the centre pin flanges. That may provide better contact in the non-crap versions. Perhaps poor manufacturing standards?
Some similar plugs braze or otherwise electrically bond the sprung multi-point contact to the plug core. Much more reliable. The loose sprung sleeve with no "wiping" contact is just asking to trap dirt and become a bad connection. Anyway, if you are trying to accurately measure low resistance then a 4-terminal technique is the answer.
Looks to me the rotating plugs create a contact by elongation and pressing into the top and bottom limits. The tarnished plugs seem to have a larger gap compared to the first good plugs and a shallower bulge compared to others. I just tested this by pushing a plug into a washer. It does elongate with the tip actually working as a wedge. Obviously the oxidation is a problem, but if some are still around, try inserting them into a properly sized hole in a washer, or other thin object, and see how the wedging action works compared to good plugs.
The resistance variation when using your shunt is due to the resistance of your body being put in parralel with a verry small resistance. You are putting both hands when you do the test. I dont see anything wrong with the connectors you tested
Also seems like the split section of the banana jack is much shorter then the solid center section. The part on the Probe Master banana jack looks like theres almost no gap there at all, while the cheap ones theres a large gap. Id say between that and the cheap coating you've found your problem Dave.
I do not trust the loose rotating contact it is not a good connection for high current or low resistance. The solid one you have was the best, when you try to rotating them there was no visible change in resistance. All the other types has a change when they was wriggled.
I believe that is called "lantern" style or "lantern plug". I have some nickel plated cheap ones, they are just as bad. It's the fit of the lantern bit that causes the problem.
You should have measured the short from solid body to body, and then the bowed slip tube to tube. There looks like a benefit to those slip tubes, in that the DMM internal tube doesn't wear out.
I am not sure those were gold plated, it looked as though they had tarnished which gold would not. Did you try to solder the cage at one end and see it the contact improved.
I had a set of One Hung Low brand banana plugs that had a spring in such a way that it did NOT press on the post when squeezed. But it didn't matter, because they were undersized and were loose in a banana jack. There was a side hole in each one so you could connect more than one, rather than a jack in the back, but the hole was too small for even those too-small banana plugs. No hope at all for a properly sized banana plug.
I think they are 'gold colored' not 'gold plated' :)
They looks like they're yellow chrome plated. I used to send stuff for yellow chrome plating if the customer wanted to powder coat the object and they wanted some rust protection on it. It's really hard to get a good finish when powder coating zinc plated stuff. One customer used to buy hot zinc plated sheet metal cheaply that were rejects from Volvo Trucks production line. Hot zinc plated sheet metal can emit hydrogen gas when heated.
You're probably right. I bet they're zinc plate and chromate passivate. Even worse, I wouldn't put it past them to have used hexavalent chrome, which is nasty stuff and has been banned. Want to know how bad? Watch the Film 'Erin Brockovich'.
I've seen 'gold earrings' that end up with a questionable finish like that...
Hexavalent chrome, or chrome-6, is still widely used in aerospace.
Its a high-risk carcinogen. There are heavy restrictions on it. I had to change the finish specs on a lot of automotive parts because finishing subcontractors stopped using it.
I don't recall ever having problems with the solid type banana plugs. The rotating ones have given me nothing but problems unless I buy expensive ones. I usually solder them so they don't rotate, then they work fine.
Which Side did you solder that worked the best for you the tip? or the other end? I like the how tight the barrel connects is & is a lot BETTER than most!!
That is what I was thinking for fixing my cheap eBay banana plugs for my speakers... As soon as I attached them I could hear dodgy connection going on...
EDIT:
Uggpff, I give up on that; melted it, I'm not good at soldering lol.
EDIT:
I got a grip and remembered I could take the plastic bits off - soldering ain't pretty but they are much better now, no dodgy connection noises.
can't believe I watched a banana plug for 15 min
The magic of UA-cam.
Same
Boom-chick-a-wah-wah......
Admit it... It took you that long to realize it wasn't motherless.
Dave could be plugging bananas and we'd still watch. ;-)
AS I'm about to buy a kit for 50 bucks (USD) that includes banana plugs as a design improvement feature. I HAD to watch it all. And now I may build my own kit-despite the additional expense.
I think they're supposed to extend lengthways when compressed, and make contact at the ends? Those seemed to have a LOT more vertical play on the shaft compared to the genuine probemaster ones
This. It seems to be a clear example of whoever made the dies and set up the machine having no understanding of how these type of connectors are meant to work.
Played with these awful ones and also some good ones. They both start out slightly loose and the moment they are in the socket, they tighten up a lot and don't 'spin' where the crappy ones still do.
The super cheap 'gold' doesn't help much either. :)
I learned this lesson when I was younger, I was using banana plugs for my speakers (they have the Screw/banana socket type) - after a while I started to get crackles and all sorts, re-wiring them (using same plugs, thinking "no way it can be them") trying a different amp / input etc... nothing resolved it, except I noticed (purely by accident) that when I moved/span the plug with the amp on, it crackled - so I cleaned the contact and the plugs, and still no difference, so I ended up swapping out the plugs and it was fine again... it did the same thing again eventually, so I gave up and now just use the screw terminal connection instead, not as easy when connecting/disconnecting but I haven't had an issue since...
I just solder it around. Worked well.
Exactly. Takes a couple of minutes Max.
Soldering one end can make them fit very tight in jacks and the surface finish on these are quite terrible to begin with. Wouldn't want to wear out the jacks on an expensive piece of gear with them.
Which Side did you solder that worked the best for you the tip? or the other end? I like the how tight the barrel connects is & is a lot BETTER than most!!
@@simontay4851 Which Side did you solder that worked the best for you the tip? or the other end? I like the how tight the barrel connects is & is a lot BETTER than most!!
Leave it to dave to turn an interesting 3 minute video into a 15 minute rambling mess.
Ashley Sommer I agree in principle; but would it really have been as effective if it were cut down to 1/5 its length? Rapid-fire really isn't Dave's style. He rambles, yes; but many viewers (myself included) enjoy the sheer entertainment value in Dave's "just look at how completely and utterly shitty this steaming pile of turd is" videos.
Thanks for this. Most people never consider these things as a source of problems. Years ago I had a terminal strip where the hard black plastic had turned semiconductor from the cleaning sprays used. Took a while to isolate that one.
Thank you so much! I've rarely suspected banana plug contacts when I troubleshoot problems on the test bench! Now I'll add it to my checklist!
Moral of the story: When your banana plugs get too tainted/corroded, check for reliability and replace if necessary!
the secondly shown multi contact plugs - LS 4 - are really high grade. Got them on stock and in use for > 25 years, practically no wear-off. of course also no corrosion. 0.02 ohm for a 50cm mc cable. You get what you pay for.
Indeed.
Because I don't have expensive stuff I know this problem since... childhood. I did solder always one loose end to the center rod and no long crying. It supports high current too.
"I can fart halfway across the room and this would change"! xD
So glad I subbed to this channel :D
Jan Christian Frodahl 🤣🤣🤣
This shit is also used on some cheap motor ESC units for drones. These can be carrying as much as 40amps at full power! Check your connectors and if the contact part rotates either solder them or best throw them away and get top quality plugs. The quality plugs have the contact barrel crimped to the center core for a perfect contact.
I'm wondering if the heat needed to solder that bit of wire on oxidized and compromised the plating. If it wasn't gold plating, this is very likely.
Sam Petrocelli He showed other ones that weren't used (just were placed in his drawer) and there was already oxidation on them.
Might have had some impact, but still crap out of the drawer.
I thought the exact same thing. I've had it happen before!
The coating looked best closest to the solder joints though. Looks more like it tarnished from contact with air or fingers.
Place your bets, guys. Is the plating:
1: brass
2: titanium nitride
3: niobium oxide
I vote "whatever was cheapest in the Shenzen Underground Coating Market that day".
Spray paint. (Ok, to be fair they dilute it with fake baby milk powder too)
That would be plating the copper with a thin layer of zinc and with some heat forming a brass layer. But that would not explain the smooth surface.
Probably brass. Looks like brass oxidisation/tarnishing to me.
Cadmium dichromate over steel would be cheapest, and goldish color, but really inappropriate for any kind of precision electrical contact. Growing up my family had an electronic connector manufacturing business, and saw lots of beautiful gold plated coax connector parts, and parts like mechanical brackets with cadmium dichromate.
After watching your video, I checked my leads that have these rotating barrels. Most were OK but a few showed resistances of as much as 3 ohms! Almost all showed changes as the plugs were wiggled. One even went momentarily open! Easy fix for them though. I just soldered the tip end of the rotating barrel to the plug. The gold ones soldered easily. The nickel plated ones needed some light scraping first. On all of them, while the solder was still molten, I slid the barrel all the way to the tip. This allows space at the top of the barrel to allow it move in an out as the leaf springs are compressed and prevents jamming or overstress of the springs. All of my leads now measure 20 milliohms or less and the wiggling issue is gone.
3:30 They forget to put a split in the rotating part, that is true.
Makes you think , they obviously don't know what they are doing.
Forget meter probes for a moment, now I'm worried about big current on bench supplies and battery connectors getting toasty with that resistance.
Gold plating is less important than tight tolerance when it comes to rotating banana plugs. There's too much play between the rotating part and the plug's core.
The rotating part is designed to longitudinally "stretch" when plugged in and apply longitudinal pressure on the core to maintain good electrical contact. If the contact pressure between the rotating part and the "core" of the plug is insufficient, you will get bad contact impedance/resistance even if both are made of pure gold.
As an alternative to scrapping those plugs, of which I have several, I'm going to try carefully soldering each end of the "cage"to the body in the hope of improving the contact resistance.
What's interesting is what happens at 12:25
there's a small drift that seems to zero out over time, my guess is that when you moved the contacts up and down you esensially heated them up by friction and changed their resistance.
I don't think the issue is so much the "split" as it is the diameter of the bad connectors. You can see the rotating bit does not have the same diameter at the ends of the rotating piece as the ends of the solid piece, and overall next to the Probemaster connectors the entire thing of the bad connectors looks like the diameter is smaller.
Isn't that what is called a "fool's gold"? I believe I've seen a list of about 20-25 different coatings that look just like gold. And many of those coatings are not conductive at all.
I got some with the same problem, and I improved it drastically by dumping a bunch of solder into the joint where it rotates. It still rotates, and it fills up the space and fixes the fit. I can go from "total crap" leads up to "cheap but works."
The cheap one is Tin casting body with possibly steel spring and gold plating just thick enough to optically look gold coloured . The good one is turned brass with brass spring and proper thickness gold plating.
are you sure it is the ring not compressing because of the lack of the split in the ring, but rather that the length of the rotating sleeve is too short for the recess on the pin. Seems to me that when compressed the sleeve will lengthen first till it comes into contact with the end stops and at that point the curves will start to deform along the long axis before any forces are high enough to start compressing the end rings diametrically.
The real problem is that , the spring sleeve should compress around the inner solid part of the plug .
To do this it needs an small air-gap between the sleeve edges , now it is rotating so freely , that it won't
though the inner solid part even if inserted in a socket .
It is possibly made to the wrong diameter tolerances , and crappy '' gold '' plating as well !
I discovered the same problem myself when I built extended leads for an RTD calibrator. I doubt I would have ever noticed it otherwise. The simple solution is just to apply a dab of solder right at the contact tip, so the spring part can't rotate and is locked in place. Haven't had a problem since.
It was probably the split not being there, preventing the cage to properly shrink and make contact on the rod.
Good to see you're back! ;)
The split was there, but didn't look very big. Likely a combo of several things, just basically poor tolerance design coupled with crap plating.
yeh looks like they did some very thin layer of of gold like ENIG on pcbs, vs. the harder thicker gold used for edge connectors
Yes, I believe you are correct. Plating is not the problem here. Mechanical design is. The split is too narrow, so the sleeve will not pinch the center pin when the plug is inserted. I have a hundred of them, but mine are even worse: The sleeve ends are dovetailed together, so there is no split at all. A quick slice with a Dremel style cutting disc will fix them.
I agree. Early in the video the split on the rotating barrel can be seen to be much thinner than on the Probemaster plug. The narrow split will close and not allow significant contact pressure with the core of the plug, when inserted into the socket. This must contribute to the problem.
Yes I bet this is the main problem. Since the cage is so loose on the shaft, the split needs to be even bigger. Try cutting away at least a millimeter and see what happens.
“Trap for young players” you said you ordered them recently.
Nice production Sir, your soldering of the 2 banana plugs is very good.
Good on ya for spending the time to make this video. Younger electricians like me don't even look for crap like this sometimes, but the second I saw how it worked it makes sense.. Good knowledge is worth the time to educate.
Looks like the gold was contaminated with iron. Seen that a long time ago on some parts we were using we had plated in house.
You can see the "gold" plating wearing off throughout the video on the tip and where its held to be inserted and removed
I have lost a lot of time from using low-quality banana plugs and test leads. (Worst was some alligator clip leads which used super thin wire and was only crimped, not soldered, sometimes without the copper even touching the clips). Nowadays I am a lot more careful what I buy.
I've had similar problems with some old tin plated banana jacks. I move the rotating part as close to the tip as possible then add a nice dab of solder on the tip end of the rotating contact point, so it's still springy. Sure it doesn't rotate anymore but the connection is solid.
I've run into banana plugs like this quite a bit. When I do I always solder the rotating part to the shaft, that usually takes care of it. The problem with the cheap ones usually is the manufacturing tolerances are too loose, which does not allow the rotating piece to grip the shaft when inserted into a jack.
A tip I got from a mate, Nigel, at The Chord Company (who make high quality interconnects and cables), which was to use the high power, clamping, soldering iron from RS. This is especially useful if you are making up speaker cables with a cross section > 2.5mm sq. There's enough thermal capacity to get the whole job done before it starts significantly heating the plug (or melting the plastic on the cable). It's a helluva lot quicker. The soldering iron is only about £50 at RS.
As the rotating flanges are compressed by the socket they elongate. That elongation pushes the ends of the flanges against the ends of the shaft indent. The loose flange with bent ends doesn't make a good contact with the ends of the shaft indent. You can see how all the others have much smaller gaps at the end of the flange, except the Farnell one, and that has a much more curved flange that would elongate more so needs that larger gap. It's that elongation pressing against the ends of the shaft indent that makes the major electrical contact, not the contract around the shaft (although that does play a part).
Possibly the manufacturer didn't use a nickel under-layer between the gold and the brass/BeCu or whatever underneath. Just plating gold directly over copper causes the gold to start diffusing into the copper and might cause pitting like that, so typically one has to add a layer of nickel plating between the copper and the gold to prevent diffusion.
I always use high quality 4mm banana plugs from hobbyking, they're for RC planes, to be loaded with like 50A and $1000 plane's "life" depends on them, you can't really get better ones.
+ add their silicone wires and you have AAA quality cables.
You are dead right they are excellent quality, plated brass. You can get these with hermaphrodite shells which can be made up to regular plugs & sockets.
Also I join them together back to back which gives me a plug with extension socket to loop into other test gear.
I do the same. I've been using connectors from hobbyking for my octorotor (with camera gear its about £6000 worth) and they are spot on although they are massive ones on that with a built in capacitor in the tip to stop arcing on connection. I made my own leads in the same way as you except I added some of their wiring loom mesh with adhesive lined heat shrink on each end. I use them a lot on site for domestic electrical testing as the mesh protects them from splitting the silicone on a stray nail!
Some of them (not from HK) are so bad that they don't even stay in the female sockets. The guys on RCGroups are recommending the ones from HeadsUpRC and Aloft. www.rcgroups.com/forums/showpost.php?p=38832952&postcount=9953
Me too, allways replace crappy hard pvc cables on crocodile clips, multimeter probes... etc. with silicone insulated thin coper fiber soft cables from hobby/RC shop, they come in all diameters, from "hair-like" to "welder wire" diameter...
It gets down below -20 deg.Celsius here (cr123a 3V lithium batteries in multimeters instead of 2*aa or 2*aaa save the day)... try using pvc insulation at that temp ;-)
"This looks terrible, Muriel" - that made my day!
I've run in to this issue before. It is the split in the expanded sleeve. I've had to pull them off and take a dremel tool and increase the gap in the sleeve. When you insert the cheap bananas the sleeve makes great contact with the jack, but the split closes before the sleeve is compressed onto the inner pin. This leaves the connection loose.
What's really the point of the sleeves being rotatable anyway? If one wants to rotate the plug while inserted the outer slits can just as well slide along the inner wall of the female plug anyway, just as with the solid kind of plugs. The main reason for the sleeves I guess is not its ability to rotate, but rather to permit the entire outer part to expand lengthwise when the slits acts as springs being compressed. Therefore they need only have a loose contact at one end, while the other ought to be soldered or crimped in place to ensure good and permanent electrical contact. One less point of failure!
Good video to raise awareness of the potential issue though, although I tend to agree with those that point out it could well have been shorter.
If you hit the rotating ones on the head the pin goes in deeper and tightens the rotating part.
I never use the rotating here in New Orleans area the humidity destroys them. All gold plate wears off eventually. This is the first time I have ever disagreed with your sage advice. I actually solder them up where they don't rotate, measure them and no issues l.
I've seen this before. The diameter of the inner pin was too small, even when the plugs were inserted they could still rotate freely. A decent banana plug should not move at all obviously. I 'fixed' it by soldering one end of the spring to the pin inside it. Looks ugly but it works.
With those plugs, I have used them, but I solder the tips (see the tip and where the fold joins 5:08) and then it does not rotate, but the springiness still does the job. It works! But if the gold plating is bad, then not much chop, throw them out.
I ran into a set that the flang didn't expand when or had bad contact when it was inserted into the female banana side. I quick work around since resistance was not a big deal for what i needed the cable for anyway, I just dropped some solder so they made contact and wouldn't spin anymore.
It is not just the 'gold plating' issues here.. like everything else, it is more complicated.
The compression gap on the crap connectors is too small. When compressed, it forms a solid ring with a diameter larger then the inside solid piece. That is the major design flaw.. a flaw shared, I might add, by the connectors you sell. The problem is more apparent in the tarnished ones, but yours appear to have the same crappy contact patch, theirs just combines that with tarnish.
Unfortunately I've purchased a few as well. I ended up holding the rotating part close to the tip and soldered the tip creating an electrical bond eliminating the rotation yet allowing to compress and move on the wire side. Hope this helps others who have in the bin!
I'm with Dave here. I've got access to a mini lathe and some pure copper rod C101. It is the best electrically but not so good for machining which is why tellurium copper C109 is what any manufacturer would choose. Then gold or tin plate. I have more than enough time to run the lathe slow for C101.
I've had loads of shit banana plugs from China, and can't afford/justify Pomona, so I will make my own ;)
Drew Dastardly The traditional material for quality contacts is brass, no plating, just solid brass. Color would be about the same, surface tarnishing should be slower.
Yes, pure copper machines poorly. On the other hand, I've seen materials machined, like C60 hardness tool steel (like a milling cutter), with the right cutter (carbide) and feeds, that I never would have imagined it possible. You might try some free cutting brass, alloy C360. These long thin connector parts are generally made on automatic screw machines, in free cutting brass, which machines really nice.
I bought the same crap plugs on eBay for putting on some wires. I got around this nonsense by just soldering the rotating part to the shaft part with a huge blob of solder. I was seeing disconnects due to the stupid plugs!
Yea, also bought some of them. I soldered the rotating part to the fixed part to at leas use them in non critical cases...
It struck me right away, no split to transfer the compression force to the connection and probably too spaced between the nose button and the rear collar, such that after compression the spinning splayed part never presses it to the nose & rear.
I'll never buy those spinning type again. Can't believe this is the 1st time I bothered to think that through.
That plug looks physically smaller than the other plugs you showed
you can see at 4:24 there aint any leverage on the carussel-springs, while on the propemaster there is equal dimension and some leverage so they can fall in under the pressure and do as intended..(bad or wrong dimension on the carussel.)
Yes as you said the rings don't have a gap. Very tarnished and pitted, looks like the new special metal now being used, known as "ElCheapolina metal :-)
I had some of these and they caused a bad problem. After only a couple of uses they began to break up and bits of the springs fell into my equipment. The rest of the plugs rapidly ended up in the bin.
Couldn't you just flow a little solder in there to solder the 'peel' to the 'banana' part? If you heat the peel up and flow it in the edge there it might get wicked in. For that shunt, they don't need to rotate so it should work.
It's not the plating. It's the free-rotating spring clips. Try soldering the spring clips to the barrel.
some things one should not cheap out on. wire. connectors. thermal paste. flux.
you spend more, yes. but you also then have a product that is supported by a known manufacturer and will actually make you want to use it more.
i have a problem with doing anything rigid like this with those connectors ... the slack of wires tends to help
but i have never understood these things anyway
it might help if you just hit the ends of the floating part with a crimper a little bit just to make them more grippy
I would not say that the high resistance is entirely related to the loose end rings and the quality of the plating. I believe that the length of the splayed contact part will increase when the banana is inserted in the jack (due to its mechanical design). This causes the end rings to form a secure contact with the “hard stops” of the inner shaft. For sure, the splayed contact part is very short in length when compared to the overall length between the “hard stops” of the inner shaft, which may be the cause of the intermitting contact/high resistance.
Soldering the rotating part to the shaft fixed it for me.
This probably explains why the ESR readings are a bit hit and miss when using the included banana probes with my Chinese transistor tester.
The problem is not only with the gold-plated banan plugs, and it is not only due to poor plating.
I bought 20 nickel plated contacts whose surface looks very good. All must be eliminated due to high contact resistance.
This is because the spring sleeve is not tight enough when connected. Test by connecting only one contact. If it is simple to rotate it with minimal force, it should go to the trash.
the issue is also the spacing at the end of the spring part, it's supposed to be forced against both end when entering
And a trap for old players too.
The rotating part is supposed to expand axially once compressed into a socket. This is supposed to make them bond on the lower/upper circular surface. When you compare proper to the dodgy ones you can feel the slight axial freedom.
I had a bunch of otherwise proper silicone wires and decided to use a crimping tool to permanently “fix” the two parts. That improved the issue quite a bit. But I found the crimping losses its power over use. I should solder them in place ...
got them, just soldered the rotating part to the case. fixes shit
The "rotating skirt" design might look cool, whether gold-plated or not, HOWEVER.... it has one major flaw: it does not give a snag and tight connection. That's why the ohm meter jumps all over the place when you wiggle or rotate the plug. The problem is the rotating skirt very loosely touching the core of the plug. If you plug in the banana in its socket and can easily spin the plug around, your connection will be intermittent. SOLUTION: solder one end of the skirt to the shaft to prevent it from spinning completely.
This is a Great way to test them , Their are so many that have a very loose fits , These one do not,,, but failed the test ,,Thank may my testing begin w this test! Thanks
I bought these crappy plugs a year ago on ebay and recognized the same problem right away. I tried to solder the turning part to the inner - that mostly solves the problem but the plugs become more difficult to fit in. I also recognized the "gold"-plating is only golden color - no quality at all unfortunately! You really get what you pay on those chinese ebay shops...
I use Mueller or Pomona connectors exclusively and have never had a problem. I've been wondering if paying extra for those has been worth it and this video confirms that it is!
Pomona makes great plugs, cables and connectors. I purchased my collection in the 70's and to date only one banana plug has failed. I've used them at home and job (Laboratory and repair). I've tested and use them reliably up to 10 amps where they get warm. Expensive but well worth the money.
It seems like as you moved the solid probes the connections warmed up a bit and the resistance increased. Then things went back to zero when you left them alone for a while.
Some of the effect you were seeing on the better quality ones may have been due to heating of the plug from your fingers when you twisted them (thermocouple). You can see how the offset settles back to zero after you stop handling them.
Same thought Jerry: also possible some very localized heating from friction as Dave twisted the plug around. You can see as he stopped twisting and continued to talk the resistance started to drop (as they cooled?).
Cheers,
Mark
************************
The problem here is the ends of the banana plugs not be able to compress against the shoulders due to the excessive clearance. As a result, there is no solid connection between the banana section and the rod.
Put them upsidedown on the bench and tap the bottom (hard) with a hammer. The longitudinal gap between the shaft and the flex is too large. Try and shrink it slightly.
The corrosion on the cheap plugs looks like it may be concentrated in areas where your fingers would touch them. I wonder if it is related to skin oils or salts. I also think that the rotating contacts are supposed to elongate when compressed by being inserted into a jack and I think it is this elongation which makes a reliable contact by jamming the ends of the rotating part against the stops on the stationary solid part. This also requires that the rotating piece be truly springy which would require a special alloy like tellurium copper.
Also: try a magnet close to them. If it attaches - it's not copper.
So solder the springy part to the plug body so it won't rotate and make good contact!
"Hard gold plating"; that's an oxymoron if I've ever heard one!
Not only banana plugs, but BNC - RCA adaptors. I bought a packet of four from e-Bay and one of them came apart when removing it from my FeelTech S3200 Dual Channel signal generator! I had to glue it up with CA glue.
There seems to be a lot of up/down movement on the rotating contacts of the crap plugs compared to all the others. When the curved splines compress it should also elongate - pressing the ends against the centre pin flanges. That may provide better contact in the non-crap versions. Perhaps poor manufacturing standards?
Some similar plugs braze or otherwise electrically bond the sprung multi-point contact to the plug core. Much more reliable. The loose sprung sleeve with no "wiping" contact is just asking to trap dirt and become a bad connection. Anyway, if you are trying to accurately measure low resistance then a 4-terminal technique is the answer.
Looks to me the rotating plugs create a contact by elongation and pressing into the top and bottom limits. The tarnished plugs seem to have a larger gap compared to the first good plugs and a shallower bulge compared to others. I just tested this by pushing a plug into a washer. It does elongate with the tip actually working as a wedge.
Obviously the oxidation is a problem, but if some are still around, try inserting them into a properly sized hole in a washer, or other thin object, and see how the wedging action works compared to good plugs.
The resistance variation when using your shunt is due to the resistance of your body being put in parralel with a verry small resistance. You are putting both hands when you do the test. I dont see anything wrong with the connectors you tested
Never skimp on test leads!
Thats what I learned early in my apprenticeship.
Also seems like the split section of the banana jack is much shorter then the solid center section. The part on the Probe Master banana jack looks like theres almost no gap there at all, while the cheap ones theres a large gap. Id say between that and the cheap coating you've found your problem Dave.
I do not trust the loose rotating contact it is not a good connection for high current or low resistance. The solid one you have was the best, when you try to rotating them there was no visible change in resistance. All the other types has a change when they was wriggled.
I believe that is called "lantern" style or "lantern plug". I have some nickel plated cheap ones, they are just as bad. It's the fit of the lantern bit that causes the problem.
You should have measured the short from solid body to body, and then the bowed slip tube to tube. There looks like a benefit to those slip tubes, in that the DMM internal tube doesn't wear out.
Its painful to see you chopping up those expensive probes Dave!!!
I am not sure those were gold plated, it looked as though they had tarnished which gold would not.
Did you try to solder the cage at one end and see it the contact improved.
I had a set of One Hung Low brand banana plugs that had a spring in such a way that it did NOT press on the post when squeezed. But it didn't matter, because they were undersized and were loose in a banana jack.
There was a side hole in each one so you could connect more than one, rather than a jack in the back, but the hole was too small for even those too-small banana plugs. No hope at all for a properly sized banana plug.
Gold doesn't tarnish. Brass maybe?
I've had this issue, it's down to the fact that the "flange" is loose and can move around.
The good plugs have a gap in the outer part so that it can be compressed to the inner part.