Wires connected without banana to binding posts (Rigol DP832 power supply) - Page 1
Forum section: electronics / testgear

author: RoGeorge
author_rank: Super Contributor
timestamp: November 03, 2024, 04:38:13 pm
content: The binding posts in Rigol DP832 have a hole drilled sideways, like in this pic found online:How is one suppose to connect a wire without banana? Do I need to crimp some pin to a wire, or a spade/fork, or just tin the wire?Asking because in practice I get unreliable contacts, and seems very cumbersome to connect/disconnect/tighten the wires. Then, either the plastic cap of the tightening screw files itself on the soldered wire, or the isolation of the wire is shredded by the tightening cap. Or, the wire strands are snipped if inserting the bare strands.Talking about a 3.2A max, so not a huge current, yet the contact resistance is big enough that I see changes in the short-circuit voltage drop while over-tightening or when test-pulling the cable.Then, if I solder the stranded wire on a piece of solid wire (meant to be inserted in the sideways hole), the wires become to high (the sideways hole is positioned vertically relative to the front panel), and the inserted wires will stay in the way of operating the buttons of the front panel. If i make tilted upwards pins, then the tilted wire tend rotate the pin inside the sideways hole of the binding post, unless the binding post is tighten really really hard.How are the binding posts supposed to be used with wires, in general? Is there some other accessory I don't know, for when attaching wires without banana to a binding posts, or is this particular model I have really bad?

author: jpanhalt
author_rank: Super Contributor
timestamp: November 03, 2024, 04:47:53 pm
content: In the ones I have seen, the top knob needs to be tightened (turned clockwise) to hold the wire and make good contact.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 03, 2024, 05:00:23 pm
content: In my connectors, turning the knob will either dent the knob edge, or shred the cable isolation. And the resulting connection is not very solid. And when tighten it really hard, it tends to cut the wire by shearing it between the nut and the sideways hole.

author: David Hess
author_rank: Super Contributor
timestamp: November 03, 2024, 05:35:42 pm
content: Maybe Rigol did not use good binding posts, because that is exactly how they are suppose to be used. I tin the stranded wire, insert it through the hole, and tighten down the binding post, as shown below. It should be good to at least 10 amps with properly sized wire.

author: IanB
author_rank: Super Contributor
timestamp: November 03, 2024, 05:43:52 pm
content: Quote from: RoGeorge on November 03, 2024, 05:00:23 pmI think you should remove enough insulation from the end of the wire so that no insulation touches the terminal or twist knob. Then tin the wire end if it is stranded. Put the tinned wire through the hole and lightly finger tighten the knob, no more. Solder is soft and will deform at the slightest pressure, making for a good contact. If you try to clamp the knob down hard you will do more harm than good.If you don't want to use the provided hole, you can also bend the wire into a J hook, place it over the pillar, and tighten the knob down to clamp it. Again, tinned wire is probably better than bare copper, which can oxidize.

author: edpalmer42
author_rank: Super Contributor
timestamp: November 03, 2024, 05:51:01 pm
content: Quote from: RoGeorge on November 03, 2024, 04:38:13 pmThese used to be called "5-way binding posts". That may have been a trademark.The 5 ways are:- banana plug in the end of the post- wire (solid or stranded) shoved through the hole and clamped down- wire (solid or stranded) wrapped around the post and clamped down- spade lug on the wire and clamped down- alligator clip in the end of the post - one jaw inside the clip, the other jaw outsideAs others have said, either Rigol used poor quality posts or you're a gorilla.

author: coppercone2
author_rank: Super Contributor
timestamp: November 03, 2024, 06:39:01 pm
content: likely you need a light source to accruately position the wireI see people fail at this often. Because they don't want to get a light.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 03, 2024, 06:50:54 pm
content: So there is no dedicated pin, or dedicated lug to crimp, and made specially for the 5-way binding posts, no secret part, only common sense. In this case, this DP832 must be having some very crappy binding posts:- The spade lugs doesn't fit well. Knob diameter is too big for the lug, so it will press against the wire instead of pressing against the flat lug.- Half alligator through the hole will stay upwards, and the alligator will cover the access to quite a lot of the front panel buttons- There is also a problem when fitting banana cables. I've just read other complained about banana holes being less than 4mm, and indeed, quality banana cables are very hard to plug in this DP832. Rigol support says it's safe to enlarge the banana holes with a 4mm drill.

author: Gyro
author_rank: Super Contributor
timestamp: November 03, 2024, 07:25:27 pm
content: Quote from: RoGeorge on November 03, 2024, 06:50:54 pmYes, only common sense.It's just to allow a wire to be inserted and lightly clamped, nothing more. Obviously the insulation must be stripped back far enough to allow the screw part of the terminal to seat cleanly rather than tilted and insecure.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 03, 2024, 07:27:03 pm
content: Quote from: RoGeorge on November 03, 2024, 06:50:54 pmThat is a stitch. One has to wonder whether they made them 5/32" (0.15625", 3.96874mm) to meet a certain market? For what size did Rogol claim they were made?

author: coppercone2
author_rank: Super Contributor
timestamp: November 03, 2024, 07:29:28 pm
content: I thought for the really high end, like keysight, they should put a light button for the binding terminals to make it easy to thread the wire. They make 500 stupid features like glowing buttons, they could add a connector illuminatorI am sure you know spade lugs come in every size? metric and imperial. From 4-40 to 1/2 inch for all wire gauges.Pick the right ones.Measure it with a CALIPER to figure out what TYPE of lug you need.Alligators are also available in a large variety of sizes. I have tons of jumpers made with different sizesThe more modern banana connectors are a bit slimmer and have more contacts. The old one have 4. So alot of modern banana connector are a bit tighter. I prefer them to use with the modern more developed connectors.Enlarging them should be OK but I would see if you can use a reamer. Then it needs to be well cleaned and greased because the coating is gone, but its easier then replacing the connectors, if you must have them compatible with the old style banana connectors (I recommend you measure your old cable resistance to make sure your not modifying stuff to have it work with defunct test cables with old style contacts that have high R )Take a good close look at a modern high end banana cable and a old one and you will see why they changed it.Good binding posts have metal on the bottom of the plastic head. Shit ones have just plastic. The ones that are beefy and have a metal plate are more then 'gently clamping' your connector or wires. I have used the larger ones for50Ano problem no heat with a ring lug or spade.I made plenty of spade jumpers for dual supplies by clamping and soldering heavy gauge magnet wire to 1/4 inch or so spade connectors. Their pretty good, of course cutting a custom metal bit and plating that would be slightly better.I consider that binding post hole to be absolutely essential to actually getting lab work done on time without always having to play technician making cables and adapters. Just strip the wire, thread it WITH A LIGHT and you can do a test like that. You can put a ferrule on it too.I am totally convinced the reason they put safety jacks on things is to make packaging cheaper. They are counter productive to everything besides high voltage portable meters, and I would still like a hand held DMM with binding posts on it (that are firmly attached not an adapter) for safe work instead of having it designed by a nanny. I should rework my 34401a's to have binding posts on them. Alright, MAYBE its a bit of a stretch to have it on a DMM because its possible to short it out connected to a big load. But they don't belong in power supplies unless their really freaking dangerous.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 03, 2024, 08:43:03 pm
content: Took a close-up picture, with a mirror underneath so to see under the knob, too. It is worst than I thought.Note how the metal shape and hole finish is different between the + and - metal rods, as if they were manufactured on different machines. It is not just the plastic color that differs, but the shape/size of the metal, too. This explains why the same banana plugs normally into - but get stuck as if it were glued when plugged into a +.Then, note how the metal ring on the knob has a large space between the nut and the center rod. Strands of wire will fit there and get cut by the screw.Then look at the metal ring on the rod, at the panel side. The metal ring is "sunk" into plastic, which means a fork lug will sit on the plastic, and will be squeezed against plastic, without touching the metal base from the panel side.Then look at the edge of the hole in the metal rod. The one on the - was deburred after drilling, while the one of the + was not. This explains the tendency of shearing a wire passed through the hole.Not to say the the nut is slightly sunk into the plastic knob, too, just like the ring on the other side. This is not very visible in the attached picture, but the plastic knob touches the other side first, before the nut. So all the first contact and pressing force against a wire (or against a spade/fork lug), will come from the soft plastic and not from the metal nut.I'll have to either go creative when using wires, or replace the binding posts.

author: watchmaker
author_rank: Unknown
timestamp: November 04, 2024, 01:24:38 pm
content: That is one example of crappy machining. It is obvious the holes are drilled before turning to diameter given the material extending into the hole on the positive post. Not even followed up with a chamfering tool. Finish speaks for itself. My guess is threaded, drilled, wire post turned to OD, shoulder, threaded for panel nut and then cutoff. The clearnace between the nut and the wire post (along with the turning marks) looks like the CNC registration for the wirepost changed; swarf caught between bit and work?Anyway, yeah, solution is to change them all. That shoulder should be proud of the insulator, or you cannot get good contact when using a spade (I use hook) crimp connection or even just wrap the wire around the post.I like the true 5 way bananas but I also standardized on sheathed banana connectors. SO on PSUs I use a plug to sheathed plug adapter. FOr serious work this would add another connection point to worry about, but I am not in the league.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 04, 2024, 02:11:22 pm
content: I know I am reiterating some of coppercone;s remarks........The hole in the binding post should be even with the base of the post, to avoid cutting the wire that would be inserted.RoGeorge observation is correct, the base plate (or whatever you call it) should be slightly above the plastic for use with fork connectors.These are not good connectors.There is a lot of conversation about good connectors elsewhere on this forum and there are plenty of poor ones. For measuring purposes with good accuracy, metal to metal should be the same without any solder. So the alloy used in the connectors is also an issue. I am not an expert on these connectors but again there are lots of conversations here and some of the "good" binding posts are expensive. As soon as you get into the Banana connector part there are issues with the metal alloys in the banana spring and their effect on measurement, Also issues about how the test lead wire is connected to the banana, solder, pressure, welded, etc. Then there are comments about plating of connectors, gold etc...For Power Supplies this is not as important and I use spade connectors whenever I can because I think they are more secure. It indeed is a challenge to find the right size horseshoe or spade connector. They probably can also handle more power but this is usually not a consideration for me. Also for PS connections soldering is a good idea for a strong connection. It is impractical to use stranded PS wire without at least tinning the ends.You theoretically would not use solder connections when measuring microvolts. You would just use clean copper wire to the hole in the 5 way binding post. The hole in the binding post is oriented vertically in my HP gear. I think this is what it should be. It is still hard to get the wire into the hole though.I have had good luck with old unused binding posts I have picked up at flea markets. I really do not know how they would perform in microvolt measuring but they are built well with good holes and threads and good solder connectors. Even the old plastic appears to be still strong.

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 04, 2024, 02:30:10 pm
content: Not sure if it makes you happy or sad but I just checked my DP832 and they are as crappy as yours. I never use them apart from plugging in banana plugs.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 05, 2024, 09:59:42 am
content: Same here, only used the DP832 with banana plugs. I did try a few times to connect unterminated wires, and didn't like it, but never investigated, just moved back to banana plugs.Banana plugs were not very good either, in the sense that the very few brand-name silicon banana cables I have, mostly do not fit in DP832, so until now I've only used DIY wires with no name Aliexpress banana. The no name banana were not that precise in their diameter, so they do fit in these wrong binding posts of DP832. But the overall quality was bad, big contact resistance and inconsistent when the wires were wiggled. That doesn't matter much for powering casual circuits, so never bothered about it.This time however, I've needed to use the power supply as a SMU, to discharge batteries and measure their mAh. DP832 can measure it's own voltage and current with 1mV respectively 1mA resolution (and over SCPI it reports an extra digit, so 0.1mV and 0.1mA resolution). That would have been more than enough to count the energy stored in a battery, except the banana connectors were showing a few 10s of mV variation when wiggled, which made me insist on looking for a better way to connect the wires.Proper fix would be to replace the binding posts, but I don't have any that could make a good replacement, plus that I'm not very willing to dismantle the power supply. I'd rather keep using banana plugs, they are faster than screwing wires anyway.I did try yesterday all sorts of ways to DIY some banana plugs that are better than the no name I've used so far. Kind of found something, but it's time consuming. Also, during all the methods I've tried, accidentally invented the "banaligator", an alligator terminated with a DIY banana pin. I'll keep that, seems very practical and fast to clip unterminated wires, though not exactly what I was looking for.For DYI banana plugs, best results were by using 8 stranded of solid copper (Cu diameter 0.5mm, or 0.02inch, striped from leftovers of CAT5 LAN cables). The 8 strands are passed through a piece of cable jacket from thin 3mm shielded cable (50ohms RG174A/U). Not silicon jacket, but very flexible, helps with keeping the strands pressed against the interior of the binding posts.These 0.5mm Cu threads looked rather soft, and not very springy, but in practice turned out to make good and consistent contacts. Probably they won't last forever, but more than enough if I think of them as consumables. How much they will last for home use, no idea, probably years. Time will tell.Don't have any proper milliohm-meter, but to give an idea, at 3.2A with a DYI copper banana at each terminal, and a soldered piece of wire between them, I get a deviation of no more than 1-2mV when wiggling the wire. This is at least 10 times better than the no name banana I have used so far.

author: tszaboo
author_rank: Super Contributor
timestamp: November 05, 2024, 10:08:35 am
content: IDK the binding posts look and work the same than I would find on any other power supply from TTI or GW or Keithley, or Agilent, pretty much anything else I used. Maybe buy some banana plugs with spring contact, like these ones:https://nl.rs-online.com/web/p/banana-connectors/3277994

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 05, 2024, 11:01:52 am
content: I use these Hirschmann cables, it's a bit of a tight fit but fine and they feel great toohttps://www.reichelt.com/nl/en/shop/product/4_0-mm_measuring_lead_150_cm_1_mm_red-130716

author: blackdog
author_rank: Frequent Contributor
timestamp: November 05, 2024, 12:05:27 pm
content: Hi,In 2016 I modified my Rigol 832 and i nthe link below you can see how I went about it.The modifications I wanted to do is to use another good fan that cools enough but gives less noise.Secondly, since the power supply was open anyway, I addressed the wiring to the banana bushings.The modification consists of twisting the power supply wiring separately from the sense wires which are now also twisted separately.I also modified the interconnection between the two channels to reduce their internal resistance.Also note where the current-carrying wires are connected and also where the sense wires are soldered, the sense wires are soldered to the PCB material and the current-carrying (thicker wiring) is soldered to the back of the banana bus.If you do this the Ri on the banana buses is as low as possible.Twisting the wiring helps the dynamic behavior and reduces the radiation from the transformer on this wiring.For soldering you need a soldering iron of a somewhat higher power, think of 100 to 200 Watt and then also with a wide tip for better heat transfer.https://www.circuitsonline.net/forum/view/130740#highlight=dp832Yes this forum topic of mine is in Dutch, live sucks *grin*You can always use a translation machine to make it somewhat readable.However, keep in mind that I type pretty crooked sentences, even in Dutch and if AI starts working with that, you will probably get something I didn't say or mean.Good luck,Bram

author: nctnico
author_rank: Super Contributor
timestamp: November 05, 2024, 12:33:47 pm
content: Typically I twist stranded wire or crimp a ferrule on it if I want to use the wires for a longer period. But it all starts with good binding posts. On lower end equipment I tend to (as in always) replace the binding posts with good quality ones from Hirschmann. These work very well.

author: passenger54321
author_rank: Newbie
timestamp: November 05, 2024, 12:35:27 pm
content: This reminds me of something very old ... my 1988 loudspeaker (attached).As you can see, not a good drilling quality, sharp edges, cheap plastic cap and only finger-tightened and no base plate at all.And it is holding the unsoldered strained cable securely since 20 years with daily shaking -- I am living close to a railway line.And the strands look pretty complete so far. So what is different with the setup you are seeing?Pointing out that soldering is not a good idea as it makes the copper inflexible - just screw the strands tightly.-Ulrich

author: nctnico
author_rank: Super Contributor
timestamp: November 05, 2024, 01:20:48 pm
content: Agreed. For long term use, tinning a wire is the worst you can do. The solder will creep causing a poor contact and it causes a sharp transition from solid to stranded which is super prone to breaking.

author: David Hess
author_rank: Super Contributor
timestamp: November 05, 2024, 07:47:07 pm
content: Quote from: watchmaker on November 04, 2024, 01:24:38 pmI took a close up photo of the binding posts (1) on my Tektronix PS503A power supply. The crosswise holes are close to flush with the bottom electrode.(1) Made by The Superior Electric Company, Bristol, Connecticut.Quote from: nctnico on November 05, 2024, 01:20:48 pmI always tin stranded wire and you can see it in the photo below. If the tin creeps up under the insulation, then it can cause a stress point which eventually breaks however this is not a problem in stationary applications. They make special heat sinking pliers which will prevent the solder from wicking but I have never used them.

author: blackdog
author_rank: Frequent Contributor
timestamp: November 05, 2024, 08:34:04 pm
content: Hi,Here are some banana binding posts from different brands.I have added some comments to the photo, the two on the right side are of poor quality.These cut the wire in two if you tighten the binding post too hard.Kind regards,Bram

author: Russ_A
author_rank: Contributor
timestamp: November 06, 2024, 03:25:49 pm
content: On my Korad power supply I took it apart so that I could re-orient all of the posts to have the post holes at a 45 degree angle. Was relatively easy to do. Makes getting wires in there quite a bit easier.

author: David Hess
author_rank: Super Contributor
timestamp: November 06, 2024, 04:33:20 pm
content: Quote from: Russ_A on November 06, 2024, 03:25:49 pmI will have to do that on mine. I am in the process of refurbishing one PS503A and then I can swap them and do the other one.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 08, 2024, 02:21:49 pm
content: Found a workaround!What bothered the most with the faulty binding posts:- the hole was too far from base, thus tending to snip the wire- the plastic edges were too high, such that the wire was not squeezed against the metal partsAt first I thought I might add an extra metal washer, and somehow solder the washer there. Not really doable. Then I've thought the washer can sit as well around the wire. Then I've realized I can just tie a knot on the wire strands.

author: rwaters
author_rank: Newbie
timestamp: November 08, 2024, 10:46:22 pm
content: Google banana spade adapter. Amazon, Digikey etc etc. Really nice ones from Pomona P/N 2305

author: coppercone2
author_rank: Super Contributor
timestamp: November 09, 2024, 07:04:00 am
content: you know why you should replace it? Because it sounds defective. I.e. it can crack and then slide into the power supply and blow it upI had this tomfoolery on my current source i bought on ebay. A creative person thought he can fix it with JB weld and super glue. When I unplugged a banana connector the banana plug metal bit came out of the chassis , energized at 100VDC, almost shorting out to the chassisIf you see common stuff that has like a obvious defect, in a electronics lab, its wise to just assume its a bad idea to use itWanna bet its made with sub standard plastic, shady additives, not tempered properly/manufactured with poor temperature control, and other defects (I am not a plastics expert)Slides right out like a tromboneThis situation with shady connectors (that can result in loose metal in the chassis) is precisely how a low voltage DC supply can turn dangerous. Such abadhabit to have in the lab with mains connected equipment. Or large batteries.Usually you should be happy about a major mechanical design flaw that you find on a part. Because it usually is hiding something else. Its like getting a friendly warning.

author: watchmaker
author_rank: Unknown
timestamp: November 09, 2024, 01:24:02 pm
content: Whenever I see poor workmanship, I look further. I learned this restoring watches where even a damaged screw raises my antenna.If the binding post source let that kind of machining pass, what else did they accept? We know they accepted a lousy design that ignored the washer under the knob and the lower shoulder set too deep. What about the "unseeable".Reminds me of the 70s/80s machine tools out of Taiwan. They were basically "Kits" the end user finished to their own standards.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 09, 2024, 02:41:19 pm
content: There certainly are other hidden flaws in this model, to enumerate a few:- a radiator too small in the first version (mine is already the version with a bigger radiator)- faulty internal wiring of the GND between channels 2 and 3 (this is mostly noticeable at high current)- the faulty twisting of force and sense wires- binding posts out of tolerance- noisy fanmaybe a couple of software bugs, too, to name only a few.Though, given its price (~$600 new, in 2015), the fact that I never needed to use it at full power, and that it was possible to unlock the mV/mA resolution together with all the other SCPI and software features made it a decent power supply.Here, in EU, the choice of second hand lab instruments is very limited when compared with what is available on ebay USA.

author: coppercone2
author_rank: Super Contributor
timestamp: November 10, 2024, 04:25:49 am
content: I took a picture so people take the warning seriouslythere is a soldered wire hook banging almost into the chassis on the back of thisSure age has something to do with this, but I noticed, cheap parts with flaws seem to age alot fasterand as I mentioned in the other thread, I had a plastic cap fall off a cartridge fuse panel mount slot, leaving a big mains wired contact on the back of the chassis.I say, never hesitate to replace suspicious hardware if it has anything to do with the outside of the machine. If your ground is good the inside is not gonna do anything too bad. But anything that can get out side of that shield needs to be dealt with.