Cleaning Plated Electrical Contacts?
in [Repair]
|
Prev: Oldest piece of working and still used test equipment ?
Next: Vertical color lines on Imiro HD-3201 TV
From: Arfa Daily on 21 Sep 2009 20:16 "GregS" <zekfrivo(a)zekfrivolous.com> wrote in message news:h984if$3mp$1(a)usenet01.srv.cis.pitt.edu... > In article > <f46025b5-ecf1-4d8c-b925-6dcb0bd5ca86(a)q14g2000vbi.googlegroups.com>, > Dubtron <swohlfarth(a)gmail.com> wrote: >>On Sep 18, 10:28=A0am, GeneO <geno...(a)yahoo.com> wrote: >>> Have been Googling the proper way to clean plated electrical contacts >>> but either get nothing if use " or a lot of nonrelevant hits without. >>> >>> Am interested in any suggestions esp how to remove the nonconductive >>> oxides. >>> >>> If a connector is too damaged would also be interested in what are >>> considered the best type replacement. >>> >>> Thanks >>> >>> Gene >> >>I have had very good luck repairing low current relay contacts and >>mechanical rotary switches using "tarn-x" silver cleaner containing >>acidified thiourea. MSDS: http://www.jelmar.com/msds/TX_MSDS_eng.pdf. >>If you take the relay or switch apart to get to the contacts, use a >>cotton swab with a small amount of cleaner and apply to the oxidized >>(tarnished) surfaces. They shine right up and the surface does not >>appear to be damaged by it. Then dry and apply a very light film of >>silicone based contact cleaner to keep the air away and help with >>lubrication. Works great for speaker relays in amplifiers and mode >>switches for VCR's. >> > > > Silicone based products are really not a good thing, at least thats what > some say. However sometimes a silicone grease is used to > protect connections. Silicone sprays were common 30 years ago. > I don't recall any of the more common recommended sprays having > silicone. I see mixed recommendations of lubing relays. > Some say no, but I do. > > greg Years ago, we used to treat the long multipole open slide switches that were fitted to dual standard TV sets, to a liberal does of white heatsink paste. This did a grand job of stopping the sections that did the timebase switching, from arcing, and the sections that did the low-level signal switching, from tarnishing and becoming intermittent. Happy days. Gentler times ... Arfa
From: Ross Herbert on 21 Sep 2009 21:59 On Mon, 21 Sep 2009 09:41:18 +0100, "Arfa Daily" <arfa.daily(a)ntlworld.com> wrote: : :"Ross Herbert" <rherber1(a)bigpond.net.au> wrote in message :news:3cmdb51o9cfgaantdo289j3dlqsbpvquj4(a)4ax.com... :> On Fri, 18 Sep 2009 08:28:42 -0700 (PDT), GeneO <genosmm(a)yahoo.com> wrote: :> :> :Have been Googling the proper way to clean plated electrical contacts :> :but either get nothing if use " or a lot of nonrelevant hits without. :> : :> :Am interested in any suggestions esp how to remove the nonconductive :> :oxides. :> : :> :If a connector is too damaged would also be interested in what are :> :considered the best type replacement. :> : :> :Thanks :> : :> :Gene :> :> :> I don't think I have ever come across a "plated" electrical contact. In my :> experience electrical contacts are always a solid material such as brass :> (cheap :> and nasty - often used in electrical appliances) or a more exotic alloy :> material :> such as nickel-silver. The contact material used is dependant on the :> application :> (AC or DC and whether inductive) and the magnitude of the current being :> handled. : : :I'm sure that you must have, Ross ?? I'd agree with you on 'solid brass :contacts' in clunky mains power switches etc, but elsewhere, many contacts :seem to be plated rather than solid. For instance, I just put the word :"plated" into the search pane on one component supplier's website, and it :came back with 59 items, most of which were connectors with a variety of :plating materials quoted for their contacts, including gold, silver & tin. :Similarly, a quick look in a catalogue at switches, reveals many to have :either gold or silver plated contacts. Also, many relays have contacts :described variously as gold "plated", "covered", "overlayed" etc. It is :these contacts that I find you have to be careful not to use any kind of :abrasion on, for fear of going through the very thin layer of plating. I :generally find that pulling a piece of dry cardboard through things like :relay contacts, is enough to clean them. A tiny spot of cleaner/lubricant :introduced to the contact gap, finishes the job off. : :Arfa : My experience has been mainly related to relays of both open and enclosed types, from miniature pcb mounted types for signal transmission to heavy duty high current capacity types. I will agree that particularly for the low level signal types the manufacturers often "enhance" the contact material by adding a gold "overlay". However, the actual relay contact will be made of some alloy material such as silver-palladium or other mixture. The contact is usually rivetted or welded to the spring leaf, which is probably a plated phosphor bronze material, while the gold overlay on the contact pips is simply to reduce contact resistance due to oxidation through lack of a wetting current. A typical relay of this type, which I have on hand, is the Fujitsu FBR46. With such relays, as you have mentioned, you never use abrasive methods of cleaning or burnishing but with gold as an overlay this should not be necessary. The problem with any "plated" contact is that once the plating material has been lost either through repeated operation or arcing etc, the base contact material is all that is left. In cases where no plating is used unless the contact material is one of the recognised traditional materials such as nickel-silver, silver-palladium etc, the electrical performance of the contact will be unreliable. Such a relay used for heavy current carrying capacity which I also have on hand is a Fuji HH62 witha contact rating at 10A. In this case the contact material is simply a "silver alloy" - probably made to Fuji specification. Such contacts can be burnished and reconditioned using abrasive tools. It may be that later contacts, manufactured for cheapness, do not use traditional solid alloy contact material which is rivetted or welded to the base contact spring material, and by so doing they would, in my opinion, be inferior to the types which do.
From: JeffM on 22 Sep 2009 01:56 Arfa Daily wrote: >That seems a bit pessimistic[...] Your blockquoting looks pretty sad. http://groups.google.com/group/sci.electronics.repair/msg/c89433e3d6dba496?dmode=source Have you heard of this 3rd-party update for your M$ software? http://google.com/search?q=inurl:jain+%22+OE.doesn't.exactly.feature.the.most.intelligent.quoting.algorithm
From: Arfa Daily on 23 Sep 2009 04:44 "JeffM" <jeffm_(a)email.com> wrote in message news:72b5f373-0266-4502-a802-c8ee67573777(a)p10g2000prm.googlegroups.com... > Arfa Daily wrote: >>That seems a bit pessimistic[...] > > Your blockquoting looks pretty sad. > http://groups.google.com/group/sci.electronics.repair/msg/c89433e3d6dba496?dmode=source > > Have you heard of this 3rd-party update for your M$ software? > http://google.com/search?q=inurl:jain+%22+OE.doesn't.exactly.feature.the.most.intelligent.quoting.algorithm Funnily enough, as soon as I replied to that particular post, I thought it looked 'wrong' ... To be fair, I don't usually quote in a way that appears "sad" or confused as far as I am aware. When my replies pop up in threads, they usually seem to look ok on my machine. However, thanks for the pointer to that piece of software. I've put it on now, so perhaps that will allow my posts to present in a way that does not further upset your sensibilities ... I'm sure you'll let me know if that's not the case ?? :-) Arfa
From: Arfa Daily on 23 Sep 2009 04:46
"Ross Herbert" <rherber1(a)bigpond.net.au> wrote in message news:s9agb51csqsndjtbatlf4tmqmgqufrveld(a)4ax.com... > On Mon, 21 Sep 2009 09:41:18 +0100, "Arfa Daily" <arfa.daily(a)ntlworld.com> > wrote: > > : > :"Ross Herbert" <rherber1(a)bigpond.net.au> wrote in message > :news:3cmdb51o9cfgaantdo289j3dlqsbpvquj4(a)4ax.com... > :> On Fri, 18 Sep 2009 08:28:42 -0700 (PDT), GeneO <genosmm(a)yahoo.com> > wrote: > :> > :> :Have been Googling the proper way to clean plated electrical contacts > :> :but either get nothing if use " or a lot of nonrelevant hits without. > :> : > :> :Am interested in any suggestions esp how to remove the nonconductive > :> :oxides. > :> : > :> :If a connector is too damaged would also be interested in what are > :> :considered the best type replacement. > :> : > :> :Thanks > :> : > :> :Gene > :> > :> > :> I don't think I have ever come across a "plated" electrical contact. In > my > :> experience electrical contacts are always a solid material such as > brass > :> (cheap > :> and nasty - often used in electrical appliances) or a more exotic alloy > :> material > :> such as nickel-silver. The contact material used is dependant on the > :> application > :> (AC or DC and whether inductive) and the magnitude of the current being > :> handled. > : > : > :I'm sure that you must have, Ross ?? I'd agree with you on 'solid brass > :contacts' in clunky mains power switches etc, but elsewhere, many > contacts > :seem to be plated rather than solid. For instance, I just put the word > :"plated" into the search pane on one component supplier's website, and it > :came back with 59 items, most of which were connectors with a variety of > :plating materials quoted for their contacts, including gold, silver & > tin. > :Similarly, a quick look in a catalogue at switches, reveals many to have > :either gold or silver plated contacts. Also, many relays have contacts > :described variously as gold "plated", "covered", "overlayed" etc. It is > :these contacts that I find you have to be careful not to use any kind of > :abrasion on, for fear of going through the very thin layer of plating. I > :generally find that pulling a piece of dry cardboard through things like > :relay contacts, is enough to clean them. A tiny spot of cleaner/lubricant > :introduced to the contact gap, finishes the job off. > : > :Arfa > : > > My experience has been mainly related to relays of both open and enclosed > types, > from miniature pcb mounted types for signal transmission to heavy duty > high > current capacity types. I will agree that particularly for the low level > signal > types the manufacturers often "enhance" the contact material by adding a > gold > "overlay". However, the actual relay contact will be made of some alloy > material > such as silver-palladium or other mixture. The contact is usually rivetted > or > welded to the spring leaf, which is probably a plated phosphor bronze > material, > while the gold overlay on the contact pips is simply to reduce contact > resistance due to oxidation through lack of a wetting current. A typical > relay > of this type, which I have on hand, is the Fujitsu FBR46. With such > relays, as > you have mentioned, you never use abrasive methods of cleaning or > burnishing but > with gold as an overlay this should not be necessary. The problem with any > "plated" contact is that once the plating material has been lost either > through > repeated operation or arcing etc, the base contact material is all that is > left. > In cases where no plating is used unless the contact material is one of > the > recognised traditional materials such as nickel-silver, silver-palladium > etc, > the electrical performance of the contact will be unreliable. Such a relay > used > for heavy current carrying capacity which I also have on hand is a Fuji > HH62 > witha contact rating at 10A. In this case the contact material is simply a > "silver alloy" - probably made to Fuji specification. Such contacts can be > burnished and reconditioned using abrasive tools. > > It may be that later contacts, manufactured for cheapness, do not use > traditional solid alloy contact material which is rivetted or welded to > the base > contact spring material, and by so doing they would, in my opinion, be > inferior > to the types which do. OK. Understand what you're saying ... Arfa |