High resistance leads on meter - Page 1
Forum section: electronics / testgear

author: Qmavam
author_rank: Regular Contributor
timestamp: February 22, 2023, 04:32:44 pm
content: I have a Bryman 235 meter, on the low ohms/beeper setting with the leads shorted, I get a 10Ω to 15Ω reading. If I use shorted dual banana plug I get zero Ωs. If I use one meter lead and touch the opposite banana connector I get 1.8Ω with either probe. I polished up the tips and did lower the resistance down to 4.8Ω to 1.8Ω. But that is inconsistent and depends on how hard I press the leads together. The problem is not broken wires in the leads, (not my first rodeo). Should I just replace the original leads and if so, who sells a compatible set of quality leads.Thanks, Qmavam

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: February 22, 2023, 05:37:49 pm
content: You are looking for Probemaster leads . Google them or search here on the forum. Everyone recommends them and now I do too!Randall

author: mwb1100
author_rank: Frequent Contributor
timestamp: February 22, 2023, 05:43:04 pm
content: Just curious - are these leads the PVC ones that come with the stock BM235 or the silicone leads that come with the EEVBlog BM235?

author: Qmavam
author_rank: Regular Contributor
timestamp: February 22, 2023, 06:05:25 pm
content: These are the silicone leads that came with the EEVBlog BM235. As far as I have found it seems to be the approximately 1" tips that have the contact resistance. If I just touch them together I can 4.5Ω to 6Ωs, but if i press them together hard and sometimes rotate a bit, I can get it down to 1.9Ωs.Mavam

author: shapirus
author_rank: Super Contributor
timestamp: February 22, 2023, 08:09:35 pm
content: This is actually worse than you get with probably even the crappiest leads you can order from China. It's just not right, I'd contact the dealer for a replacement, if possible.

author: TimFox
author_rank: Super Contributor
timestamp: February 22, 2023, 08:22:04 pm
content: On non-fancy leads supplied with DMMs, I've never seen any with probe-probe resistance greater than about 0.5 ohms.I agree about recommending the ProbeMasters.

author: Qmavam
author_rank: Regular Contributor
timestamp: February 22, 2023, 09:17:43 pm
content: I have too add, the probes where not like this when new. I have had the meter, several years, 4 to 6, company replacement is not expected. I thought the problem was the banana end and used DeoXit on the banana parts, without any positive effect.I have included a picture of my probe tips, The seems shiny enough although the tips are dull! The problem shows when I touch the probes together 3/8" from the tips. If I press them together very hard I can get the resistance down to a minimum, sometimes I need to rotate the tip a little to, I'm surmising a lower resistance area on the probe.

author: shapirus
author_rank: Super Contributor
timestamp: February 22, 2023, 09:28:08 pm
content: Quote from: Qmavam on February 22, 2023, 09:17:43 pmYou mean their resistance used to be okay, and then it increased? This definitely doesn't sound like the problem would be in the tips then, because that would mean that their material changed its electrical properties dramatically.More likely it's bad contact between the tip(s) and the place where they connect to the wire inside the body of the probe. It could be verified by another multimeter (or better a TR-1035 or similar) by measuring the resistance across the exposed length of the tip.

author: TimFox
author_rank: Super Contributor
timestamp: February 22, 2023, 09:30:35 pm
content: Quote from: shapirus on February 22, 2023, 09:28:08 pmIt could easily be the surface condition of the tip (corrosion, etc.) or possibly a connection inside the probe handle to a tip.

author: Fungus
author_rank: Super Contributor
timestamp: February 22, 2023, 10:23:18 pm
content: Are they gold?I only use gold these days. The Brymen gold leads are only about 12 bucks.

author: bdunham7
author_rank: Super Contributor
timestamp: February 22, 2023, 11:09:54 pm
content: Quote from: Qmavam on February 22, 2023, 09:17:43 pmWere those originally gold-plated and the plating has worn off? Have you tried cleaning them with IPA (alcohol)?

author: Fungus
author_rank: Super Contributor
timestamp: February 23, 2023, 06:36:06 am
content: What sort of abuse have they suffered?

author: DimitriP
author_rank: Super Contributor
timestamp: February 23, 2023, 08:02:25 am
content: Chuck'em and get a pair of these:https://probemaster.com/8000-series-test-leads-only/

author: sonpul
author_rank: Regular Contributor
timestamp: February 23, 2023, 09:24:05 am
content: I've already seen reviews of Brymen probes degrading. Brymen do not use soldering. The crimp connection wears out over time due to oxidation.

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 23, 2023, 12:11:28 pm
content: Quote from: sonpul on February 23, 2023, 09:24:05 amMy many years old Greenlee DM820A (rebadged Brymen 827S) came with silver (nickel plated?) silicone probes. They've been abused and wrapped around the meter all their lives and still work just fine. I consider them very good quality and have had no problems with oxidation.The probes shown by the OP seem to have been polished or otherwise had their gold plating stripped off. Somethings seems awry there. I recently purchased the eevblog BM235 and the probes are wonderful in my opinion. They zero out and have no issues whatsoever.If I ever needed a set or replacement probes, there's little doubt I would go for the Probe Masters... But the Brymen's I've got work perfectly well, and I do like to use the probe holder in the boot (the Probe Masters do not fit there).

author: shapirus
author_rank: Super Contributor
timestamp: February 23, 2023, 12:46:09 pm
content: Quote from: TomKatt on February 23, 2023, 12:11:28 pmHe mentioned that he polished them in a troubleshooting attempt. The issue existed before that.

author: BillyO
author_rank: Super Contributor
timestamp: February 23, 2023, 03:32:31 pm
content: Doesn't the EEVBLOG BM235 come with the gold plated leads? My 786 did.

author: Qmavam
author_rank: Regular Contributor
timestamp: February 24, 2023, 03:20:46 pm
content: Quote from: shapirus on February 23, 2023, 12:46:09 pmWhile looking at the ProbeMaster probes I saw a picture comparing the Bryman probe to the ProbeMaster probe. The Bryman was goldplated, I looked at mine, the threaded area is still gold, but I could only find a tiny part on one probe that had any gold on it.I can think of nothing I did to remove the gold, Yes, I did rub it on the carpet to try and remove any tarnish, but by the time I did that, I was already having problems, because the gold was gone. It must have been very then plating. I'll be ordering the ProbeMaster probes. See picture attached. of good tips vs my tips.

author: shapirus
author_rank: Super Contributor
timestamp: February 24, 2023, 03:41:57 pm
content: Wow. I thought you polished them in order to actually remove the plating to make sure it wasn't it that added the extra resistance. If it's not the case, then I wonder what else could happen to these tips that not only removed the plating, but also dulled their ends to such an extent. They definitely lived a hard life.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 24, 2023, 04:10:39 pm
content: Quote from: Qmavam on February 22, 2023, 04:32:44 pmThat's actually pretty common. Just about all meters will read like that. You really are seeing the resistance of the leads as well as the resistance of the DUT (Device Under Test) (all three in series) which is technically correct. Most meters are not designed to read in the low ohms range very well. If you want to read ONLY the DUT resistance then you need to use a 4-wire meter with Kelvin connections to the DUT. That technique nullifies the test lead resistance and all you will see is the resistance of the DUT.That said: Yes some leads have more resistance than others but ALL test leads have some resistance and that resistance has to be taken into account if you're testing DUTs that have very low resistance.

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 24, 2023, 04:21:13 pm
content: Quote from: Stray Electron on February 24, 2023, 04:10:39 pmI've never observed dual digit resistance values from the test leads alone on any decent DMM. If you cross probe tips, you should certainly have less than 10 ohms IMO. The leads are the DUT in that case.

author: shapirus
author_rank: Super Contributor
timestamp: February 24, 2023, 04:48:59 pm
content: I have yet to see a set of leads that (when new) measure higher than 1 Ohm.I have not however measured any of the crappy leads I have that came with the cheapest meters, maybe they would.

author: bdunham7
author_rank: Super Contributor
timestamp: February 24, 2023, 05:47:14 pm
content: Quote from: Qmavam on February 24, 2023, 03:20:46 pmYou may want to consider getting this style. The sharp spring tips are nice for probing small things and PCB traces. They are hand-assembled and sometimes look like it, but they work very nicely. I'd also recommend the retractable bananas over the right-angle.https://probemaster.com/spring-loaded-micro-tip-test-leads-only/

author: shakalnokturn
author_rank: Super Contributor
timestamp: February 24, 2023, 11:20:45 pm
content: Do you have a decent constant current lab power supply and thermal camera ?

author: Qmavam
author_rank: Regular Contributor
timestamp: March 03, 2023, 03:00:49 pm
content: I received my ProbeMaster probes. On the MΩ scale, it immediately reads 0.2Ω then increments to 0.0 within 4 seconds. On the beeper/Ω scale it starts with a flash of high numbers then drops to 0.4 and takes 6 seconds to reach 0.0.So the probes are great, I don't understand the 0.0Ω.Is the meter calibrated to remove lead resistance?Happy with my lead kit, not happy with the $54 price. Hopefully they will last 20 years, when I don't expect to need them any more!Qmavam

author: Wmesquite
author_rank: Newbie
timestamp: March 04, 2023, 05:16:27 am
content: I'd expect a pair of Probemasters to be higher than 49 milliohms, so measured by an accurate meter with higher resolution would give a figure that would round to 100 millohms/ 0.1Ω. Maybe it is off by 30 milliohms on the whole scale. Regardless, getting a measurement to within 1 digit is well within the resistance accuracy spec of .3% + 3 digits. Brymen might even tilt the scale down a hair on low ohms, if nothing else everyone would bitch about the crappy leads Brymen sent if their leads read 0.2Ω on a meter that was half to 1 count off in the other direction.