Title: Multimeter's rotary switch lubricant Post by: Signal on December 28, 2015, 03:52:44 15:52 My multimeter (Axiomet AX-105) after years of reliable work started to show incorrect unstable values of low resistance. The reason was - old lubricant over contacts of rotary switch.
After cleaning by alcohol a good contact is back and becomes even better than was new - typical 0.1 Ohm value of short circuit now is 0.0 almost all time. But I think that purpose of lubricant is a protection of contacts from abrasion. What is your experience or knowledge? What kind of lubricant do you use as a replacement of aged one? Is it easy accessible? Or do you simply leave it dry without further sad consequences? Title: Re: Multimeter's rotary switch lubricant Post by: solutions on December 29, 2015, 12:14:42 00:14 Any decent meter, including an old analog one with a galvanic movement, can be zeroed out and should be, for leads' and contacts' resistances.
That said, unless someone knows of something better, there's a conductive grease that typically is used to protect lead acid battery terminals from corroding and from acid exposure - I'm guessing that MAY work. Title: Re: Multimeter's rotary switch lubricant Post by: Gallymimu on December 29, 2015, 03:09:11 03:09 The lubricants are often helpful in preventing corrosion as well as fretting.
This can work for cleaning (but it sounds like you got it clean) http://www.amazon.com/CRC-05101-QD-Electronic-Cleaner/dp/B000CCMLD0 I think this might be what solutions is talking about http://www.alliedelec.com/mg-chemicals-846-80g/70125869/?mkwid=sabYU23qn&pcrid=30980760979&gclid=CNSTt4iNgMoCFQ9afgodXnQJPQ But honestly I'd personally use non-conductive grease like a silicone / dielectric grease (http://www.adhesivecentral.com/cgi-bin/commerce.cgi?preadd=action&key=LT-37535-BP&gclid=CMTRy_KNgMoCFUWVfgodF1wBBA) That said these are primarily used to exclude moisture and oxygen from the connection. I've not seen grease used on the wiper contacts of any Fluke meters I've ever used. Also bear in mind if the hard gold or hard tin coatings have worn off the wiper or PCB then it will be forever difficult to clean and keep working because contact abrasion and fretting will be more prevalent than it was when the original coatings were present. Title: Re: Multimeter's rotary switch lubricant Post by: Signal on December 29, 2015, 03:13:25 15:13 Any decent meter, including an old analog one with a galvanic movement, can be zeroed out and should be, for leads' and contacts' resistances. If shorted Ohmmeter indicates form 2 to 120 Ohms depending on light touches to the switch knob and indication changes in time itself that is not the case for trimming/zeroing.That said, unless someone knows of something better, there's a conductive grease that typically is used to protect lead acid battery terminals from corroding and from acid exposure - I'm guessing that MAY work. Conductive grease spread over dielectric surface of board between exposed contacts looks irrelevant. I am pretty sure - it is not applicable here.Title: Re: Multimeter's rotary switch lubricant Post by: dR-mR on December 30, 2015, 11:21:47 11:21 I used that lubricant for my old multimeter without problems
http://www.wurth.co.uk/technical-chemicals/lubricants-and-rust-removers/lubricating-grease/hhs-grease-400ml Title: Re: Multimeter's rotary switch lubricant Post by: Signal on December 30, 2015, 12:13:11 12:13 I used that lubricant for my old multimeter without problems ... I suppose that you use one from reserves on your shelf. How long do you use the multimeter after application of that lubricant?Title: Re: Multimeter's rotary switch lubricant Post by: dR-mR on December 30, 2015, 12:34:59 12:34 3 or 4 months.
I gave the multimeter to a friend he works with car electronics, i think he still use the multimeter. The lubricant i got from the same friend Title: Re: Multimeter's rotary switch lubricant Post by: sotos234 on January 02, 2016, 08:43:37 08:43 Silicone Dielectric Grease is preferred.
Title: Re: Multimeter's rotary switch lubricant Post by: Mega32 on January 03, 2016, 06:47:13 18:47 Use Caig Deoxit
See TechNote 012 from Kron-Hite (They make serious references, based on dial wheels) http://www.krohn-hite.com/htm/technotes/technical_note.htm#Technical%20Note%20#012 Caig DeoxIT D5 for cleaning http://store.caig.com/s.nl/it.A/id.1602/.f Note PreservIT is now : DeoxIT® Shield , for lubricant after cleaning http://store.caig.com/s.nl/sc.2/category.192/.f Nice reading about the productlines http://store.caig.com/s.nl/it.I/id.22/.f Mega32 Title: Re: Multimeter's rotary switch lubricant Post by: zac on January 03, 2016, 09:38:24 21:38 I have had good results with Cramolin (now called Deoxit) products:
http://store.caig.com/s.nl?sc=1&category=&search=cramolin Title: Re: Multimeter's rotary switch lubricant Post by: mylogin on January 31, 2016, 05:08:40 05:08 Deoxit works great for my multi-meter rotary switch, phone jack, Ethernet jack, RF connector, and power adapter connector contact, especially for old instrument switch contacts. --highly recommended.
Title: Re: Multimeter's rotary switch lubricant Post by: bobcat1 on January 31, 2016, 08:31:56 08:31 Hi
I use this cleaner for contact clean for many years - proven to do the work http://www.maplin.co.uk/p/servisol-super-10-switch-contact-cleaner-200ml-jp17t All the best Bobi Title: Re: Multimeter's rotary switch lubricant Post by: GroundPlaneLoop on February 05, 2016, 07:03:43 19:03 Isopropanol with a little white mineral oil works also good.
Title: Re: Multimeter's rotary switch lubricant Post by: Signal on January 24, 2017, 12:53:01 12:53 I found "KONTAKT CHEMIE Kontakt Gold 2000" as an ideally targeted solution though the cost is higher (14euro/200ml).
(http://uk.farnell.com/productimages/standard/en_GB/81781805-40.jpg) http://www.crceurope.com/wwwcrc/tds/TKC3%20KoGold2000.pdf General properties and applications: KONTAKT CHEMIE Kontakt Gold 2000 is a long-lasting and temperature-resistant lubricant. The synthetic oil forms extremely thin layers with minimum influence on the contact resistance of electrical contacts. The lubricant has proved to be particularly effective for contacts with surface coatings of soft metals, e.g. gold, silver, tin. The corrosion-inhibiting effect of noble-metal coatings is improved considerably because they are no longer scratched by mechanical loads and vibrations. KONTAKT GOLD 2000 "Protective lubricant for metal-plated contacts" is referenced in technical data sheet of another product: KONTAKT 61 Contact lubricant & corrosion inhibitor: http://www.crceurope.com/wwwcrc/tds/TKC3%20Kontakt61.pdf 1. GENERAL DESCRIPTION Mineral oil based contact cleaner for all types of electrical contacts. Cleans, lubricates, displaces moisture and prevents corrosion. 4. DIRECTIONS <...> To reduce the wear and tear of soft noble metal (coated) contacts, we do recommend the use of our synthetic contact lubricant KONTAKT GOLD 2000. <...> Title: Re: Multimeter's rotary switch lubricant Post by: Signal on November 27, 2017, 03:40:46 15:40 Just have cleaned and reapply "KONTAKT CHEMIE Kontakt Gold 2000". After 11 months resistance of contacts rapidly becomes much worse than zero - about 30 Ohms changing by tens from rotation to rotation.
Title: Re: Multimeter's rotary switch lubricant Post by: optikon on November 27, 2017, 11:14:12 23:14 Just have cleaned and reapply "KONTAKT CHEMIE Kontakt Gold 2000". After 11 months resistance of contacts rapidly becomes much worse than zero - about 30 Ohms changing by tens from rotation to rotation. OK good to know... perhaps the issue is that the Gold 2000 is just a conductive lubrication but does not address the oxidation that was present which continues to degrade. Were the contacts first treated with something that removes oxidation? Gold 2000 corrosion inhibitor means that it slows / stops additional but didnt address the original existing condition? Title: Re: Multimeter's rotary switch lubricant Post by: Signal on November 27, 2017, 11:46:45 23:46 OK good to know... perhaps the issue is that the Gold 2000 is just a conductive lubrication but does not address the oxidation that was present which continues to degrade. Multimeter has "gold" contacts on PCB and bronze sliders. There are no signs of corrosion on both. And I used only isopropanol for cleaning that I believe does not clean oxidation. What I noticed before cleaning - grooves in the layer of old lubricant that looked thickened. Maybe I sprayed too much, do not know.Were the contacts first treated with something that removes oxidation? Gold 2000 corrosion inhibitor means that it slows / stops additional but didnt address the original existing condition? It definitely does not address to remove initial corrosion, as I understand description (see above in this thread).The main target of using lubricant was to protect "gold" layer on PCB from abrasion. Ten months of usage before reapplying is not perfect at all but still does not bother me yet. Will see next year ;) Title: Re: Multimeter's rotary switch lubricant Post by: papy_bidouille on November 28, 2017, 08:55:13 08:55 I used a lot of faith with succes this type of special grease for conact electric moving made by SIEMENS type WAHLER FET T.
I did not have any more or could find some Title: Re: Multimeter's rotary switch lubricant Post by: Gallymimu on November 28, 2017, 03:05:40 15:05 Just have cleaned and reapply "KONTAKT CHEMIE Kontakt Gold 2000". After 11 months resistance of contacts rapidly becomes much worse than zero - about 30 Ohms changing by tens from rotation to rotation. It's likely a losing battle. The original plating on the contacts may be gone (I realize you said it was not) and corrosion may set in MUCH more quickly now. Also there could be pitting, or loss of spring force on the contacts as well. I've never had these things work "like new" after cleaning and lube. |