How crappy crappy test leads can be? - Page 1
Forum section: electronics / testgear

author: piranha32
author_rank: Unknown
timestamp: July 02, 2013, 05:27:28 am
content: Hello,I've got recently a used HP3478A multimeter. Since it came without any accessories and I can't use any of the test leads I have at home (they have shrouded plugs), I checked ebay if I can find something what I could use. My only requirements were that the leads should have un-shrouded banana plugs and should not cost more than the multimeter itself. I found a set of ebay-branded cables fitting my requirements, with a nice set of interchangeable attachments:Since the cables were pretty cheap, I did not have high expectations. I knew the insulation would be stiff, the probes would be blunt, but that was ok for me. I have a set of nice Pomona leads and I found shrouded to unshrouded banana converters (which are sitting currently somewhere in the mail system on the way from China), so the el-Crappo wires would be used only on rare occasions.When the package came in mail, I wanted to see how they work (and play with my new multimeter). The quality was exactly as I expected: blunt probes, stiff insulation, no protection of connections to attachments. No surprises here. It started to be more interesting when I measured a low-value resistor. The measured value was ~1.5ohm higher than what I expected. Quick check of resistance, and yes. The shorted "wires" have resistance of over 1.5ohm!I used 4-wire measurement to make sure that the resistance of the contact in the socket will not affect the result.For comparison, the home-made leads using real wire have two orders of magnitude lower resistance:Out of curiosity I measured also resistance of one of the leads: 0.8ohm!This thing must me made mostly out of plastic, with only a single, hair-thin strand of metal inside.If Dave will not be too disgusted to touch this junk, I'm tempted to mail it, so he can make a torture show during one of the mailbag segments to the enjoyment of the viewers.regads,Jacek.

author: Unknown
author_rank: Unknown
timestamp: July 02, 2013, 05:31:27 am
content: Doooo eeeeeeeet! And tell us where you got them so we can avoid them.

author: piranha32
author_rank: Unknown
timestamp: July 02, 2013, 05:33:22 am
content: Quote from: duskglow on July 02, 2013, 05:31:27 amThey are all over ebay. I posted image grabbed from one of the sellers, so you can see what not to buy.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: July 02, 2013, 06:05:41 am
content: Quote from: piranha32 on July 02, 2013, 05:27:28 amIt was sent from Hong Kong, not China

author: piranha32
author_rank: Unknown
timestamp: July 02, 2013, 06:07:54 am
content: Quote from: iloveelectronics on July 02, 2013, 06:05:41 amApologies. From Hong Kong. Not China

author: profmason
author_rank: Contributor
timestamp: July 02, 2013, 06:48:26 am
content: Experienced the same thing with ebay alligator leads. The problem is that the leads are crimped to the wire and they it's poor penetration through the insulation. Soldering the connections gives reasonable performance.Cheers

author: AlfBaz
author_rank: Super Contributor
timestamp: July 02, 2013, 07:09:27 am
content: Why dont you just buy normal leads and simply cut the shrouds off?

author: mazurov
author_rank: Frequent Contributor
timestamp: July 02, 2013, 07:31:19 am
content: "Normal" leads fail too. I bought a pair of Agilent leads several months ago (the only type of Agilent equipment I can afford new :-)) and one is already open internally. At the same time, I have some crappy no name leads that are still good after 10+ years.Just buy another pair or two.

author: AlfBaz
author_rank: Super Contributor
timestamp: July 02, 2013, 08:05:08 am
content: A friend of mine at work complained that his meter leads were open cct and wanted to check them on my meter. They were still open. We determined the problem was in the red probe after piercing the insulation. The probe wasn't a moulded type and we eventually figured out how to get it apart. There was a damn fuse in the probe

author: ftransform
author_rank: Frequent Contributor
timestamp: July 02, 2013, 10:35:43 am
content: steel

author: piranha32
author_rank: Unknown
timestamp: July 02, 2013, 03:02:22 pm
content: Quote from: AlfBaz on July 02, 2013, 07:09:27 amI could. But I don't like to slice nice cables unless I really have to.

author: AlfBaz
author_rank: Super Contributor
timestamp: July 02, 2013, 03:15:38 pm
content: Quote from: piranha32 on July 02, 2013, 03:02:22 pmFair enough

author: Neilm
author_rank: Super Contributor
timestamp: July 02, 2013, 06:07:34 pm
content: Quote from: AlfBaz on July 02, 2013, 08:05:08 amFused leads are required in some countries for measurements in some places. Hence the reason in wasn't moulded.Neil

author: jancumps
author_rank: Unknown
timestamp: July 02, 2013, 06:33:48 pm
content: I have two pairs of those leads. They are what they are: convenient but low quality.

author: Unknown
author_rank: Unknown
timestamp: July 02, 2013, 06:47:04 pm
content: Fused leads for voltage measurement are a stupid idea in my opinion. I know the correct procedure is to always check with a known voltage before *and* after testing an unknown circuit, but you should make it hard for people to mistakingly believe the circuit is off, not easy by having a voltmeter read '0V'. This is especially true if there's no blown fuse indicator.

author: xrunner
author_rank: Super Contributor
timestamp: July 02, 2013, 06:53:44 pm
content: Look at these pieces of junk I got from MPJA -http://www.mpja.com/The solder job was a complete FAIL. They sent me replacements and they were just as bad.

author: Smokey
author_rank: Super Contributor
timestamp: July 02, 2013, 07:19:28 pm
content: heh, that red IC hook looks like the ones I got from allelectronics.comhttp://www.allelectronics.com/make-a-store/item/MTC-5/2-MINI-HOOK-JUMPERS-5-PACK/1.htmlFor 6.50USD you get 5 cables, all different colors. I ordered a few batches. They are actually pretty good quality for being so cheap, and work great until they break. The only issue is that the little plastic loop at the end of the hook that the metal hook pushes the wire against when you close it, that thing is kind of fragile and they break off leaving you with a hook that won't hook on anything.I usually break one every couple months. Once you have a couple cables with one side that is broken, you can scavenge the good ones and make one functional cable out of two. I don't feel bad about desoldering the cables and using the hooks for custom test cables since they were so cheap to begin with.Of course after reading that it sounds kind of silly. Ya don't listen to me. It probably makes more sense to just start with Pomona cables that will last forever (or until you accidentally melt them).

author: david77
author_rank: Frequent Contributor
timestamp: July 02, 2013, 07:28:40 pm
content: This is why I make my own test leads - that way I know exactly what I get.Made a couple of BNC to banana leads this weekend from old 10Base2 network coax, shielding up to the hot banana plug. If you could buy test leads like these they'd be pretty expensive.

author: xrunner
author_rank: Super Contributor
timestamp: July 02, 2013, 07:32:28 pm
content: Quote from: Smokey on July 02, 2013, 07:19:28 pmThe copper strands were horrible. They weren't even shiny. It looked as if they came out of some nasty acid bath. Bad news all around.

author: Smokey
author_rank: Super Contributor
timestamp: July 02, 2013, 07:53:15 pm
content: The allelectronics wires were pretty good. good soldering too.I'm pretty sure you can get those same cheap IC hooks from dealextreme, but they are all the same color. Having the 5 different color cables is nice.

author: piranha32
author_rank: Unknown
timestamp: July 03, 2013, 03:59:21 am
content: Quote from: mazurov on July 02, 2013, 07:31:19 amNormal leads fail. These are a failure. I have a few sets of decent leads, just I wanted to get quickly something without shrouds. I knew they were crap, just I did not realize how crappy crap they were.

author: piranha32
author_rank: Unknown
timestamp: July 03, 2013, 04:15:07 am
content: Quote from: Smokey on July 02, 2013, 07:53:15 pmI've got from Seeedstudio a set of leads with hooks for Buspirate and they have different colours (wires and hooks.). They have also leads for Open Bench Logic Sniffer, with IC hooks. Again, different colours.The quality is not exceptional, but good enough for the price.

author: AlfBaz
author_rank: Super Contributor
timestamp: July 03, 2013, 05:09:44 am
content: Quote from: david77 on July 02, 2013, 07:28:40 pmI'm guessing the cable is RG58, maybe RG59. If so I that's what I have done. The other day however, I had a strange incident that I didn't have time to investigate further where I found one of these had heaps of noise. I replaced it with some normal flying leads and the noise dropped markedly

author: John Coloccia
author_rank: Super Contributor
timestamp: October 20, 2013, 08:09:59 pm
content: I just tried these from...uhm...RadioShack. I know, I know...I tell people to NEVER by anything from Radio Shack...not even batteries.Well I saw these and they actually looked pretty decent:http://www.radioshack.com/product/index.jsp?productId=11931581They looked pretty good...tips were sharp....comfortable...fit snuggly in my Fluke 87, etc etc. Seemed to have everything going for it. Even the initial resistance readings was pretty low. .3 Ohms, or something like that. Not too bad. And then came the continuity test. Touched the leads together and what do I hear?*Beeeeeppppppp Beep Beeep Beeeeeeep Beeeep Beep Beep_______________BEEEEEEEEEPPPPPP __________ BEeep Beep*The metal they're made out of is so incredibly crappy that the contact from lead to lead is intermittent. My original Fluke 87 leads are over 15 years old and they work as well as they did the first day. These are JUNK, and they've already gone back to Radio Shack. They were only in my shop for 5 minutes.What a shame. They were really nice otherwise. I just wished they'd work.

author: Lightages
author_rank: Unknown
timestamp: October 20, 2013, 08:42:54 pm
content: I am working right now on a test lead shootout/review. Part one should be released before the end of this month. Yes, there is a lot of crap out there.

author: mmilejski
author_rank: Contributor
timestamp: October 20, 2013, 08:57:05 pm
content: Quote from: Lightages on October 20, 2013, 08:42:54 pmAre you going to review only readily made test leads?For a few weeks now I am searching around for quality banana plugs, crocodile clips and test hooks to make cheap(er) test leads. I've already found many good ones (4mm plugs used by Franky, for example), but I want to see what is the best on the market.

author: John Coloccia
author_rank: Super Contributor
timestamp: October 20, 2013, 09:24:47 pm
content: I just ordered some Pomona probes for $15.00 USD from Digikey, and apparently they're pretty darn good and very well made. I don't think I could make leads myself for that cheap, and they wouldn't be anywhere near as nice.Maybe it's different outside of the US.

author: xbb
author_rank: Newbie
timestamp: October 20, 2013, 10:17:37 pm
content: Quote from: John Coloccia on October 20, 2013, 09:24:47 pmThey are the same as the Fluke leads, you can buy them from mouser also if you are outside of US.If you want to use your shrouded leads with the 3478a you can get some adapters like the pomona 6728

author: Kryoclasm
author_rank: Regular Contributor
timestamp: October 20, 2013, 10:47:59 pm
content: As much as it hurts my wallet to buy anything made by Pomona, you cant go wrong... top quality. Just make sure you take care of them.If I need leads that will be abused I make my own.

author: senso
author_rank: Frequent Contributor
timestamp: October 20, 2013, 10:57:22 pm
content: Quote from: John Coloccia on October 20, 2013, 09:24:47 pmI also purchased a sort of Starter kit and a pair of mini-grabbers made by Pomona (from Mouser), for like 40€, nice quality cables, with the usual sharp probes, one long needle probe, alligator clip, spade, and something else, very nice, not THAT expensive.

author: IanB
author_rank: Super Contributor
timestamp: October 20, 2013, 11:54:30 pm
content: Quote from: John Coloccia on October 20, 2013, 08:09:59 pmI have two sets of these and they work nicely for me. Soft, flexible, sharp tip, 0.1 ohm resistance.Not sure what your continuity problem might have been. Maybe grease on the metal surface?

author: nanofrog
author_rank: Super Contributor
timestamp: October 21, 2013, 03:15:55 am
content: For those in the US, Probemaster is another option (don't have much of a presence outside of the US from what I understand).Most of what I have is from them (DMM stuff), and have been quite pleased with it. Not cheap, but does seem to offer a little more value for the money vs. Fluke/Pomona.

author: Lightages
author_rank: Unknown
timestamp: October 21, 2013, 03:53:47 am
content: Quote from: mmilejski on October 20, 2013, 08:57:05 pmYes, only ready made leads. I do have leads from Franky so you will see the quality of his products too.

author: Dark Prognosis
author_rank: Regular Contributor
timestamp: October 21, 2013, 04:02:15 am
content: Quote from: iloveelectronics on July 02, 2013, 06:05:41 am1997, cough.

author: rstoer
author_rank: Regular Contributor
timestamp: October 21, 2013, 04:21:46 am
content: Quote from: nanofrog on October 21, 2013, 03:15:55 amI'll second that. Their 9000 series modular leads are great. Made in the USA. I prefer them to Pomona.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: October 21, 2013, 04:41:30 am
content: Quote from: Dark Prognosis on October 21, 2013, 04:02:15 amLOL..Yes, technically HK is China. But my point was that HK Post and China Post are completely separate and independent operations

author: nanofrog
author_rank: Super Contributor
timestamp: October 21, 2013, 04:42:03 am
content: Quote from: rstoer on October 21, 2013, 04:21:46 amDefinitely a bigon the 9000 series. The 8000 basic leads are nice too, as are the pogo versions of them (I like the "softie" grips on them, but they may feel strange to some at first).

author: grenert
author_rank: Frequent Contributor
timestamp: October 21, 2013, 05:08:47 am
content: Quote from: IanB on October 20, 2013, 11:54:30 pmI think there was a thread here some time ago regarding coatings placed on test leads (perhaps to keep them shiny?). IIRC, a quick brush with steel wool took care of the problem.

author: Dark Prognosis
author_rank: Regular Contributor
timestamp: October 21, 2013, 05:15:32 am
content: Quote from: iloveelectronics on October 21, 2013, 04:41:30 amAye and that surprises me after 16 years. I would have thought HK would have been sucked up under the Red Chinese grasp by now considering HK is such a vast port of wealth.

author: Whuffo
author_rank: Regular Contributor
timestamp: October 25, 2013, 10:45:38 pm
content: I visit HK from time to time and I've noticed that over the years the British / white population has decreased to almost none while the Chinese are everywhere and things have been gradually changing to the Chinese way.

author: ahnuts72
author_rank: Regular Contributor
timestamp: October 26, 2013, 02:45:02 am
content: Quote from: IanB on October 20, 2013, 11:54:30 pmI also have a set and a little scrub and some ipa and they work great.Miles above the ones that came with my meter.

author: John Coloccia
author_rank: Super Contributor
timestamp: October 26, 2013, 04:36:23 am
content: I considered that, but then I thought that if I did that and they still didn't work, now I'd have to fight them for a return because I "ruined" them. I just said screw it and ordered the Pomonas.

author: mzacharias
author_rank: Frequent Contributor
timestamp: October 26, 2013, 07:40:27 pm
content: Really late getting into this thread, but I would like to mention that the shrouds on conventional, newer, high quality test leads can be very successfully trimmed back for use with older meters. Do it all the time, using Fluke or Agilent leads with a Simpson 270, or with for example a Fluke 8800AF. If done correctly, the shrouding can be so trimmed as to not expose any metal under normal usage. I know people freak out over this, but really. Conventional 4mm banana plug ends have been used perfectly safely for fifty years or more.

author: piranha32
author_rank: Unknown
timestamp: October 26, 2013, 08:13:02 pm
content: Quote from: mzacharias on October 26, 2013, 07:40:27 pmOf course you can cut the shrouds, but this will alter the leads permanently. It's not always possible to use adapters, but having such option, I'd rather leave the leads intact and use the converter.

author: Dark Prognosis
author_rank: Regular Contributor
timestamp: October 31, 2013, 11:56:40 am
content: Quote from: Whuffo on October 25, 2013, 10:45:38 pmYes, I watch DigitalRev TV and they do a lot of shots walking the streets, going to the ports, going all over HK and I just don't see many, to any, non Asians in the foreground OR background scenes. So, I must concur and 20 years is now considered a generation so it is time but I wonder why all of the non Asians left? I know in 1995-1996 there was a mass exodus of the concerned types but from everything I gather HK is still a pretty laid back, and free, place to live unlike the mainland.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: October 31, 2013, 12:25:51 pm
content: Quote from: Dark Prognosis on October 31, 2013, 11:56:40 amI don't to want to get political but HK has been changing, especially since the new Cheif Executive took the seat last year. He has been a terrible leader and is the enemy of pretty much the entire population now. We are being turned more and more "red", if you know what I mean. There have been more and more very serious conflicts between local grown HK people and mainland immigrants and even visitors.Anyway, I shall stop here before turning this thread into something else.

author: Whuffo
author_rank: Regular Contributor
timestamp: October 31, 2013, 02:04:06 pm
content: Quote from: Dark Prognosis on October 31, 2013, 11:56:40 amIt's an administrative zone of China; they still have their own immigration, customs, etc. It's MUCH easier to ship products to the world from Hong Kong; you'll find many, many of the Chinese manufacturers have offices in Hong Kong for this reason. They load up a semi in Shenzhen, drive it across the border to Hong Kong, then break it into individual packages and ship it to the world. Check a map; you can just about throw a rock from Shenzhen to the Hong Kong border.My new scope was shipped to me from Shenzhen - it took FedEx 10 days to get it here, and it came with a very fat pile of shipping / customs documentation. Lots of bureaucracy; one day when I have a little free time I'll go through that pile and admire all the forms, seals, etc. But I'll keep on buying things from China / Hong Kong - besides the weird "Yum Cha" brand stuff, top quality name brand stuff is also available and its MUCH less expensive.

author: mos6502
author_rank: Frequent Contributor
timestamp: October 31, 2013, 02:31:16 pm
content: It's not just test leads. It's all kinds of cables. Many seemingly copper cables are now "CCA" (copper coated aluminum). Another trick they use is to make the insulation extremely thick and just put five tiny strands of wire in the middle. I had a set of jumper leads that I once got from my automobile club. One day, the battery on my car was dead and I used them. Well, they didn't work. But they seemed nice and thick. Luckily, my friend who jump started me had his own set. So at home I cut them open, turns out the "cables" were 95% plastic with a few tiny "copper" (probably steel or aluminum) strands in the center.

author: Dark Prognosis
author_rank: Regular Contributor
timestamp: November 02, 2013, 01:00:56 pm
content: Quote from: mos6502 on October 31, 2013, 02:31:16 pmMy test leads on my $1.99 Harbor Freight type meter had 4 in it. I had it for a few years and the black lead just came apart at the jack side. I tried to fix it but no go when I noticed it had 4 strands in it.Every single item I have tried to fix for my mother came from China and all of the wires have less than 6 strands of copper in them and to help reinforce them they use (on some of them) hot glue. Try repairing and scoping stuff out with it moving around and the wires break on you quickly. No matter how many times you solder them they will break again until you just want to throw the circuit board as far as you can.