Lubing a multimeter's range select switch - yay or nay? - Page 1
Forum section: electronics / testgear

author: LeonR
author_rank: Regular Contributor
timestamp: July 06, 2021, 08:50:39 pm
content: I've opened a couple multimeters and noticed that in some models there's a residual oily substance, probably to alleviate the friction between parts on the switch and the PCB.Is there any product widely available that is OK for this scenario? Or should I just keep those contacts clean with a electronics contact cleaner/IPA?I've read some positive reviews about Deoxit, it seems like a good option.Thanks!

author: Gyro
author_rank: Super Contributor
timestamp: July 06, 2021, 08:56:53 pm
content: Knock yourself out...https://www.eevblog.com/forum/beginners/lube-dmm-selector-switch/https://www.eevblog.com/forum/testgear/can-i-grease-my-dmm-selector-with-silicone-oil/Those should cure your curiosity!

author: AVGresponding
author_rank: Super Contributor
timestamp: July 07, 2021, 05:30:45 am
content: Quote from: Gyro on July 06, 2021, 08:56:53 pmOr leave you more confused than ever!

author: Cymaphore
author_rank: Regular Contributor
timestamp: July 07, 2021, 08:21:06 am
content: Personally I prefer to use lube on sliding contacts. That is based on my experience with sliding ring contacts in electric machines, where using the right grease makes a big difference in reducing wear and arcing.Based on a recommendation of a friend of mine who works a lot with high voltage electrical machinery, I use CG70 for multimeter rotary contacts. That is a contact grease for light pressure sliding contacts, suitable for high voltage applications with a wide temperature range. Maybe overkill.If the rotary switch doesn't feel good when turning or making noises, I lube the mechanical parts with silicone grease. But that is mainly for comfort reasons.Both of thease measures combined usually result in a much smoother handling of the switch. If it actually makes a difference about wear or contact resistance, I can't tell, but I would guess so.

author: LeonR
author_rank: Regular Contributor
timestamp: July 07, 2021, 10:50:30 am
content: I forgot to add my experiences with this:I tried applying a very small dab of silicone grease (standard grade) into one my multimeters. After ~6 months, the meter started to act weird when turning on and changing ranges. Cleaned it with IPA and voilà, working as intended again.I've also had bad experiences with WD-40 for electric/electronic. After some months the oil gets sticky and adheres to metallic surfaces like a paint coating, making it pretty hard to get off from the parts without resorting to stronger stuff.

author: Fungus
author_rank: Super Contributor
timestamp: July 07, 2021, 11:20:20 am
content: If it ain't broken, don't fix it.

author: David Hess
author_rank: Super Contributor
timestamp: July 07, 2021, 05:17:51 pm
content: My choice for this would be a non-silicon lubricant like PPE (poly phenyl ether) which can be found in some switch lubricants. My guess is that that is what you found.

author: kcbrown
author_rank: Frequent Contributor
timestamp: July 07, 2021, 06:47:49 pm
content: Calling joeqsmith, calling joeqsmith ...This would actually be a fascinating thing for him to test. Does lube on the contacts make any significant difference in their longevity? He could get a couple of cheap multimeters, put lube on the selector switch contacts of one of them, not put lube on the other, and run it through his range switch exerciser until one or both of them wears through.Might even be able to test multiple lubes that way, see which one works out the best.It won't be proper statistical testing, of course (sample sizes of 1 tend not to be) but it would make for an informative video nonetheless, IMO.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 07, 2021, 11:33:03 pm
content: Quote from: kcbrown on July 07, 2021, 06:47:49 pmA few may remember I did a short video showing WD-40 and dielectric grease. That WD-40 was fairly conductive and took a lot of effort to clean out. I also had shown temperature effects on Vasoline. We also had a discussion about flashover and I ended up running a simple voltage breakdown test for Fungus. I don't think there was little doubt that the GE grease I used greatly improved the breakdown voltage.Of the meters I have life cycled, some used grease, others not. The meter that has performed the best during this test was the Fluke 17B+and it used dry contacts.That's an incorrect statement. The 17B+ uses a lot of grease.Some meters with grease were destroyed. If you chose to run two new 17B+ vs two free meters from Harbor Freight, you may find completely different results. The type of grease may make a measurable difference too. Consider that it requires 60 hours to reach 50,000 cycles. The worst part is you know some idiot is going to start adding what ever product holds up the best in the test. That could be very bad as well.Give it some thought. What types of lubrication, what meter to select, metrics to collect, number of cycles... For the meter, if you used the free Harbor Freight, I don't think the one I tested made it 2000 cycles. But it was free. The 17B+ is about $130/ea. One for each test. Could easily wrap $1000 into it and a month of run time. Best to have some very clear goals in mind.

author: Cymaphore
author_rank: Regular Contributor
timestamp: July 08, 2021, 05:34:29 am
content: Quote from: joeqsmith on July 07, 2021, 11:33:03 pmI would think of a test with only one model, preferably a better cheap one. Test cases:* Ungreased* Vaseline* Proper contact greaseIdeal would be s sample size of 2 per case, to have a better comparison. Each testee is then ran by a certain amount of switching cycles. Maybe 1-2 intermediate inspections after 30% and 60% could be useful.I would donate to support such a test. Sounds quite interesting.

author: Fungus
author_rank: Super Contributor
timestamp: July 08, 2021, 08:05:04 am
content: Quote from: joeqsmith on July 07, 2021, 11:33:03 pmie. Adding grease to a Fluke won't improve it, adding grease to a cheap meter won't necessarily save it.Me? I think it comes down to the materials used in the selector switch contacts and the design/quality of the PCB. Grease won't change either of those. If it's the wrong sort of grease then it might make things worse in ways that a short-term test doesn't reveal.Quote from: joeqsmith on July 07, 2021, 11:33:03 pmThat sentence doesn't parse very well, but, irregardless: If you're regularly causing sparks inside your meter then you need a better meter and/or better work practices. Grease is only a band-aid at best.

author: Cymaphore
author_rank: Regular Contributor
timestamp: July 08, 2021, 09:13:33 am
content: Quote from: Fungus on July 08, 2021, 08:05:04 amComparing different meters to evaluate the performance of the grease doesn't really make sense. If we want to know the actual impact of lubing and how big the difference is, the compared meters have to be identical and only differ in the lubing aspect.

author: Fungus
author_rank: Super Contributor
timestamp: July 08, 2021, 12:19:19 pm
content: Quote from: Cymaphore on July 08, 2021, 09:13:33 amOf course. My point was that such a test will tell you very little about applying grease any other model/brand of meter.Worse: Casual readers might think the resultdoesapply to their meter.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 08, 2021, 04:14:55 pm
content: Quote from: Fungus on July 08, 2021, 08:05:04 amYou may recall that some of the Fluke branded meters I looked at used grease while others did not. I suspect that if there were no gains to be had Fluke wouldn't have added it.Quote from: Fungus on July 08, 2021, 08:05:04 amThat is really bad. No doubt that adding the GE grease increased the breakdown voltage.Quote from: Fungus on July 08, 2021, 12:19:19 pmI agree.It seems like if the goal was to test different lubricants, you would follow some industry standard for that. If the goal is to see how a specific meter would behave with and without a specific type of grease then I think we need to know what those metrics are. If we wanted to look at the wear for example, maybe we are using special equipment like I have to measure it. If we wanted to know how the breakdown voltage changes over the life of the meter for example, what would be the procedure?I don't think this test would be a trivial to run and in the end, I really don't see what we would learn from it. Worse, the majority of people will read all sorts of mumbo jumbo into it. I still to this day have people asking me about testing various surge protectors and talking to me about safety over the other tests I have ran to determine some idea how robust the meters were.

author: Cymaphore
author_rank: Regular Contributor
timestamp: July 08, 2021, 04:48:04 pm
content: Quote from: joeqsmith on July 08, 2021, 04:14:55 pmI have absolutely no doubts about the reduction in arcing if it is a proper lube designed for such kind of a contact (like the GE-stuff you used or CG70 that I applied). That's a prime reason why lubing is mandatory for certain sliding contacts and switch types. But in a DMM that probably only becomes is even relevant if other means of input protection are already catastrophically failing.My interest was in the difference after a certain amount of rotary cycles. I don't think there is an industry standard for that for measurement instruments. If the lube has relatively a positive impact on the wear and contact resistance. By comparing identical lubed / unlubed meters, visually and the contact resistance, that could give an indication if the lube actually has an impact on PCB-based switching contacts in the long run.But you are correct, if people just read it without thinking, they might think it is some sort of universal answear to the question.

author: peteru
author_rank: Regular Contributor
timestamp: July 08, 2021, 05:42:44 pm
content: Quote from: Cymaphore on July 08, 2021, 04:48:04 pmVaseline is the universal answer to most questions. In all other situations, baby oil is the alternate answer.

author: kcbrown
author_rank: Frequent Contributor
timestamp: July 08, 2021, 05:58:47 pm
content: Quote from: joeqsmith on July 07, 2021, 11:33:03 pmFor the test to be useful, the only lubricants I'd think that would be worth considering are those that donotinhibit conductivity between contacts, seeing how the idea is to preserve the full functionality of the meter. And, of course, the lubricant cannot itself be very conductive, if at all, since otherwise you'd almost certainly wind up creating conductive paths between selector tracks that were intended to be insulated from each other. Chances are that automatically puts you into special-purpose lubricant territory. It would be useful to test multiple brands and types of lubricants that meet the conductivity requirement.For the meter, you'd want it to be something cheap. The idea is to test the effect of the lubricants relative to running the meter dry (and a cheap meter will almost certainlynothave lubricated contacts from the factory. You might make dry contacts from the factory a requirement of any meter being considered, unless you know what lubricant the factory is using (in which case one of the meters you'd test would be that meter with its lubricant removed).It occurs to me that some meters will have gold plated contacts and others won't. So you might need to use two sets of meters, one with gold plated contacts and one without. If there are multiple plating options for the non-gold-plated contacts then I'd say whichever type tends to be the most common in the multimeter offerings is the one to use for the non-gold-plated option.While I realize that there is likely to be a considerable difference in the contacts (e.g., with respect to the thickness of the plating) between a higher priced meter and a lower priced one, the idea here is to examine the effects of the lubricants. So I'm inclined to say whichever meter is cheapest and has gold plated contacts is the one to use for that option, and then for the non-gold-plated meter, you choose whichever one is cheapest and has the type of plating that is most commonly found across meter makes and models (as opposed to in the meter population itself, i.e. you ignore how many units of any given make and model are out there).I haven't a clue what lubricants to consider for the test, other than that they can't inhibit conductivity or markedly increase it.There are two different effects I think we'd want to see tested here. The first is, of course, the number of cycles of the selector switch that can be tolerated before failure. The second is to see how much of an effect, if any, the lubricant has on the accuracy and functionality of the meter. The latter might be something worth recording against number of cycles of the switch so you can see how the accuracy of the meter changes with switch use with the lubricant in question, and compare against how it changes when the contacts are not lubricated.Anyway, should make for some interesting results.

author: Cymaphore
author_rank: Regular Contributor
timestamp: July 08, 2021, 06:23:44 pm
content: Datasheet Electrolube CG70/Other contact grease and oil products from themThere are similar products available from a variety of vendors (3M, GE).Products from this particular brand have been used by myself in test applications of up to 3kV (contact protection with a high voltage withstand test with climate system for the automotive temperature range of -25°C ... 85°C).In that particular case the lube used prevented wrong insulation readings due to humidity on the surface of the testee holder after heating up from the low temperature phase.

author: Fungus
author_rank: Super Contributor
timestamp: July 08, 2021, 06:29:19 pm
content: Quote from: joeqsmith on July 08, 2021, 04:14:55 pmTrue.This makes me suspect that the benefit isn't in the lubrication. Maybe it's to do with creepage, moisture resistance or something like that.Quote from: Cymaphore on July 08, 2021, 06:23:44 pmThere you go.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 09, 2021, 12:08:47 am
content: Quote from: Fungus on July 08, 2021, 06:29:19 pmCould very well be.It's been 6 years so I double checked and glad I did. I was totally backwards. The 17B+ was really slathered up with grease where the 107 uses dry contacts. Corrected above. The 107 had survived to the highest transient levels I've exposed any meter to but the switch is not near as complex at the 17B+. If the grease was added for wear, odd they would not use it with the 87V, or across the board.

author: Microcheap
author_rank: Frequent Contributor
timestamp: July 09, 2021, 12:52:50 am
content: Quote from: LeonR on July 07, 2021, 10:50:30 amWhich grease are you using? I had the opposite experience. Two of my cheap meters had problems with oxidation in the switches' contacts, after cleaning the PCB with IPA and applying a little amount of silicon grease, the problem was solved. I did the same with all my other multimeters and I haven't had any problem for a while.I'm using a grease fromImplastec:

author: Cymaphore
author_rank: Regular Contributor
timestamp: July 09, 2021, 06:05:39 am
content: Quote from: joeqsmith on July 09, 2021, 12:08:47 amSpeculation based on observation on vehicle component production lines:Maybe because of the high quality of the traces (thickness, anti corrosion surface) and the slides, it passed whatever internal requirements they have even without the lube.And if the input protection measures already effectively prevent arcing within their requirements anyways, that would altogether be a good argument for not adding it to the production process.Good contact lube is expensive, messy and due to possible harm to workers (allergies, etc.) requires usually extra precautions and procedures in the production line and for service handling. It would be reasonable to avoid that process by taking other measures.You usually don't take means to further exceed requirements if the product is already over exceeding requirements without the procedure in question.

author: LeonR
author_rank: Regular Contributor
timestamp: July 12, 2021, 12:39:46 pm
content: Quote from: Microcheap on July 09, 2021, 12:52:50 amI used the same as you - Implastec. Actually, the multimeter started acting weird (poor display contrast even on good batteries, display shutting off after changing ranges, etc) after ayear and half.The multimeter in question is an Aneng 8009.

author: Monkeh
author_rank: Super Contributor
timestamp: July 12, 2021, 03:35:09 pm
content: Quote from: LeonR on July 12, 2021, 12:39:46 pmSo a reasonable lifetime for a cheap lump like that lubed or not.

author: AllSystemsMalfunction
author_rank: Newbie
timestamp: July 12, 2021, 07:32:32 pm
content: Lubricating plastic clicking mechanism with dense grease - not so terrible, but lubricating contacts - bad idea: it may arc over if grease if slightly conductive.... also it may start reading wrond