Any suggestions on how to make a home-made contact deoxidizer? - Page 1
Forum section: electronics / general

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: November 09, 2015, 03:36:27 pm
content: Hi everyone,I'm on the process of restoring a Tek475 scope.I didn't realized that WD40 can cause corrosion on electrical contacts. I already applied a descent amount of it on most if the switches recently, so now I have to re-do the task and wipe off that chemical to prevent it from causing much serious problem. It must be urgent. Can you suggest any type of deoxidizer chemical or how to make home-made contact deoxidizer suitable for such application?Elex

author: oldway
author_rank: Super Contributor
timestamp: November 09, 2015, 11:39:23 pm
content: I was using carbon tetrachloride as degreaser and contact cleaner.I think it could remove WD40 from contacts of your TEK 475.NB: indeed, WD40 can't be used as contact cleaner !But I advise you : carbon tetrachloride is a dangerous product with severe adverse health effects, such as causing fulminant hepatic necrosis.Don't inhale it and use gloves.Use it only outside in a well ventilated area and at your own risk !

author: timb
author_rank: Super Contributor
timestamp: November 09, 2015, 11:49:08 pm
content: Take the switch arrays out and wash and scrub with with Dawn dish detergent. Rinse throughly with water and then with 97% IPA and let dry. Then apply DeoxIT (red) spray while rotating the switches. Let it dry 24 hours. Optionally apply DeoxIT Protection (blue) spray as above as well for additional corrosion protection.Sent from my Tablet

author: oldway
author_rank: Super Contributor
timestamp: November 10, 2015, 12:32:08 am
content: Have you already done this with a TEK 475 ?You have to remove the vertical and time bases boards to do what you said...that's a lot of work.With carbon tetrachloride, you don't need to remove these boards.As far I know, it not harmfull for boards and components.elex_enthusiast do not want to use industrial deoxidizer.If he would, I recomend F2 Special contacts from KF CRC industries.

author: Macbeth
author_rank: Super Contributor
timestamp: November 10, 2015, 01:53:42 am
content: Quote from: timb on November 09, 2015, 11:49:08 pmUnfortunately all these proprietary brands of stuff are not so simple to find in the rest of the world. Dawn dish detergent? Is that like Fairy Liquid? I normally hear of something called "Simple Green" which seems to be the industrial detergent of choice in the USA. Now 97% IPA is something I can easily get ahold of (I've got a gallon of 99.9%). But then you present DeoxIT (red) and (blue). WTF are they? Some versions available from Farnell but very pricey compared to other contact cleaners in the UK and to be honest I really don't want to spray anything on my equipment if all it has is a brand name and some anecdotes.Now I've had good results from using the local cheap contact cleaner that all service shops use, Servisol Super 10. But thats on shitty old TV's and VCR's or anything with crap switches, trimmers and pots. I really would not dream of spraying any old shit like that on a very sensitive analog board, say in a 6.5+ digit meter or a precision resistor decade.What I am getting at is there must be some proper methods of cleaning contacts based on the materials they are made of and the proper chemicals to use rather than some magic "works wonders" nostrum, given a brand name and then different "colours" too because the magic elixir is not selling so well anymore...

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 02:33:10 am
content: Unfortunately most service engineers aren't cross-trained as organic chemists and as metallurgists, so there is a relatively large market opportunity for selling snake oil, lovingly hand-milked from invisible mice fed a diet of pure four leaved clover, as long as it isn't immediately actively harmful to the circuit. Seehttp://www.pitt.edu/~szekeres/cleaner.htmwhich at least should help you clear up the Cramolin Red/CAIG DeoxIt confusion.Whatever cleaner you use *MUST* be safe on all plastics commonly used for components, the most sensitive of which is probably polystyrene. If you are going to use one not sold for low residue circuit board cleaning, try some in a jam jar with a block of expanded polystyrene foam and a block of closed cell polyurethane foam + samples of any othe plastics you know to be present (e.g. Perspex for light pipes, bezels, display windows etc.) for a week and check the samples for degradation (appearance, surface condition, strength and brittleness) before you use it on the electronics.For USA only propriatry cleaning chemicals, you can usually match them up to something 'real-world' from their MSDS datasheets, but beware of additives when using them for non-obvious applications. The original choice may be because it was empirically found to have/not have a nontoxic additive that is at levels that don't need to be declared, but is critical to the non-standard use.

author: ez24
author_rank: Super Contributor
timestamp: November 10, 2015, 03:36:44 am
content: To OPHard to get an answer huh?I emailed these guys and could not get a straight answer (for oscope contacts)http://www.caig.com/But probably timb's answer is the best so far

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: November 10, 2015, 04:40:24 am
content: Quote from: oldway on November 09, 2015, 11:39:23 pmThank you guys for all your suggestions. I really appreciate those:-+I prefer to purchase a more common deoxidizer that is available on hardwares locally, or, make a much safer and easy to make deoxidizer since the need for it is urgent. Actually I don't have much experience with using different kinds of chem for different application. How about this type of contact cleaner?:Is it any good?By the way, I bought an all purpose oil. I wonder if its good enough for lubricating trimpots:Elex

author: Vgkid
author_rank: Super Contributor
timestamp: November 10, 2015, 05:16:42 am
content: When you mentioned alternate oils to lubricate switches, that got me thinking...Im considering picking up a container of superlube synthetic ptfe oil.Also consider looking looking into fishing reel oil, those are often rather nice. I come from a family that is into hunting and fishing.

author: BradC
author_rank: Super Contributor
timestamp: November 10, 2015, 06:25:23 am
content: Quote from: elex_enthusiast on November 10, 2015, 04:40:24 amNote, this is *my personal* experience, not from a web site, nor from a book or theory. It may be totally incorrect but it has worked for me for many, many years.I've found the quickest way to permanently ruin a pot (trimpot/fader/whatever has a carbon track) is to move the wiper while anything is wet with solvent (water/IPA/Unicorn blood/whatever). The solvent can soften the track and let the wiper damage it severely. So wash and dry thoroughly, then lubricate and operate.Singer oil is a pretty good lubricant for a light mineral oil. Your biggest enemy when using a lubricant is oxidation. This causes the lubricant to break down, get gummy and make a mess. For anything with a carbon track these days I use Caig labs Faderlube. I give them a good wash with Isopropyl alcohol to get the old grunge out, let them dry thoroughly and then lube them up.For other lubrication I've moved away from light machine oil and now use Amsoil synthetic compressor oil instead. It has similar mechanical characteristics as light mineral oil, but it *seems* to me to last longer because it oxidises less (or slower). It's probably one of those 95% things, but I use it in the headstock bearings on my Lathe for the same reason (it does not oxidise into a gummy mess over years, keeps lubricating and is easy to clean up) so I always have a bottle floating about. Singer oil is infinitely better than WD40 for any application requiring lubricant. WD40 is good for removing stickers, cleaning shower screens, degreasing hands and displacing water on wet ignitions.. that's about it.Back to contact cleaner, I used to use whatever I had lying about but these days it's Caig Deoxit D5 or D100 for oxidised stuff, or IPA and a bristle brush for mostly anything else.

author: coppice
author_rank: Super Contributor
timestamp: November 10, 2015, 06:38:49 am
content: Quote from: BradC on November 10, 2015, 06:25:23 amI find peanut cooking oil is better than WD40 for removing stickers.

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 06:45:24 am
content: I cant find a MSDS or a product datasheet for the Philips 390CCS spray, but it supposedly contains a lubricant and protectant, and can you trust a 'contact cleaner' that says its suitable for bicycle chains? Really? W.T.F.!!!It *might* be OK for cleaning the daggy bits out of the trailer socket on a sheepfarmer's ute, but I certainly wouldn't use it on delicate electronics.If I was going to mix my own, and wanted one that left a lubricant behind it, I'd blend 5% of Oleic acid B.P. with Liquid Paraffin B.P. and dilute the mixture to 10% with Naptha (lighter fluid). That gives you a contact surface enhancer and a protective hydrocarbon oil, both extra pure, and a volatile carrier. Apply sparingly and topically with a clean artist's brush or a dropper, don't dunk the whole bloody board in it! You could try dilution with IPA, instead of Naptha but it may not make a stable solution.For static contacts exposed to damp that are *NEVER* mated or disconnected under load, you can use dielectric grade silicone grease for corrosion protection, but silicone greases and oils must never be used on a moving contact as any sparking oxidises them forming very persistent insulating residues on the surfaces. Remember, SiO2 is *SAND* and forms *GLASS* with heat and metal oxides! For similar reasons you don't want PTFE particles left behind.

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 09:02:02 am
content: Why do you want to replace the Oleic acid. Its not too difficult to get reasonably cheaply in small quantities, and has a long history in the field. Do you have any cites for Polysorbate 20 as an electrical contact treatment?

author: timb
author_rank: Super Contributor
timestamp: November 10, 2015, 10:35:42 am
content: Quote from: Macbeth on November 10, 2015, 01:53:42 amLOL. No, DeoxIT isn't snake oil. It's very well respected and pretty much the best of the best for contact cleaners.There's three main versions: Original (red colored), Gold (yellow, for cleaning gold plated contacts) and Shield (blue, used after original to provide additional corrosion protection in harsh environments).There are also several formulations and applicators available. There's two versions of the aerosol spray: D100 and D5. D100 is pure DeoxIT and D5 is 5% DeoxIT, the rest being IPA. The advantage to the latter is you can spray it inside a semi-sealed switch, as the IPA evaporates leaving just the DeoxIT. D100 must be wiped off the contacts once applied. (I only buy D100 now; if I want to clean a switch or something where I can't directly get to the contacts I simply mix 5 drops of D100 with IPA and use a syringe with a 16ga needle to inject it right where I need it; works great!)Anyway, this stuff has been around many years and there's hard science behind the effectiveness. It's expensive, yes, but from my experience nothing works better. I've restored at least one hundred pieces of vintage test gear, so I'm not talking out my ass here.Sorry for assuming you were in the US; Dawn is a common degreasing dish liquid here. (It works so well they use it to wash birds and other animals after oil spills; seriously, it's true!) Any degreasing dish soap should work, as long as it has no fragrances or anything.Fun Fact: Back in the day, when Tek got scopes in to refurbish or repair, they would literally wash them. With soap and water. CRT, circuit boards and all. They'd do a rinse with deionized water (deionization removes minerals and other contaminants, which is what causes water spots) and dry it in a oven (at low temperatures, of course).Sent from my Tablet

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 11:14:18 am
content: Another fun and useful fact anyone water washing boards (or dealing with wet electronics in general) should know:Isopropanol forms a negativeAzeotropewith water that boils at 80.4 deg C. If the IPA is over 88% (by weight) of the remaining liquid on the board it will always form the Azeotrope as it evaporates, so you can be reasonably certain the board is totally dry if held at 90 deg C, for long enough for the IPA smell to dissipate. A spray can of 97% IPA is your friend! If you have a lot of wet clean boards to dry, its worth catching the IPA runoff and using it to pre-rinse and partially air dry the next batch so you don't have to use as much 97% IPA to finish drying them. Of course you do have to watch out for parts that may not be fully hermetically sealed, as moisture sucked into a cavity due to rapid cooling during the wash process then not fully dried is a major issue.

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 11:34:56 am
content: Quote from: 3roomlab link=topic=58124.msg797277#msg797277If you are going to use anything other than extremely pure chemicals in a contact treatment, the residue could have unwanted characteristics e.g. be corrosive or form a tough varnish layer. I specced medicinal grade Oleic acid and Liquid Paraffin (highly purified water clear light mineral oil) for a reason.Buy the right commercial product, or do the literature search and come up with a DIY version, but if you are going to try random vaguely similar liquids, worst case: you may find it would have done less damage to piss on it then spray it with WD40!Incidentally, for 'dry' cleaning sensitive circuits, we tended to prefer Servisol Aero Clean 50. Even so, really sensitive circuits often needed a 'bake-out' next to the heater to get them back on frequency. Servisol Super 10 (switch cleaner) is *NOT* suitable for PCB general cleaning, except for wiping edge connectors. It is however quite good as a label remover! We ordered both in case lots for workshop use.

author: nctnico
author_rank: Super Contributor
timestamp: November 10, 2015, 08:16:25 pm
content: If contacts are corroded the only solution is to replace them. Deoxidizer makes them work long enough to get the apparatus replaced. Contact cleaners contain aggressive components by definition because they need to eat through the oxide layer. It is a good idea to wash away contact cleaner from an apparatus and repair it properly. However if it has been left in for too long the contact cleaner will have attacked other parts of the device and the device will be ready for the trash can. I have experienced this several times already.

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 08:29:14 pm
content: Google:oleic acid "112-80-1" site:ebay.comMake sure you get medical grade liquid paraffin oil, not to be confused with paraffin lamp fuel.The 5% dilution in paraffin oil is to reduce the oleic acid concentration to limit its slight corrosive effect. That ends up as 0.5% after the dilution with naptha, which used sparingly should be O.K on all except the most delicate contacts. Its almost certainly not as effective as some commercial contact cleaner lubricants, but it also should be less corrosive than those with high oleic acid concentrations.No Ophidian lipids specified or required!

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 08:48:21 pm
content: Quote from: nctnico on November 10, 2015, 08:16:25 pmSometimes you need heroic measures. E.g. a car electric mirror controller that was basically wiping contacts direct on PCB pads. The pads were shot to s--t, but fortunately not badly burned through. Repair consisted of abrasive cleanup of the pads and re-tinning wiped to a smooth finish. The moving contacts were retensioned and carefully dressed and polished followed by lubrication with petroleum jelly B.P. initially thinned with some Servisol Super 10, and its still reliable on my daily driver over five years later.

author: Ian.M
author_rank: Super Contributor
timestamp: November 10, 2015, 09:57:38 pm
content: Take off site:ebay.com and put your country or nearest big city - you might get lucky.

author: helius
author_rank: Super Contributor
timestamp: November 10, 2015, 10:39:23 pm
content: MSDS will tell you some of the components but rarely all. You may see "trade secret ingredient non-hazardous" or just nothing and the balance is what they don't tell you about. But oddly enough some formulas are patented and you can find the exact contents in the patent. For example, Stabilant (which I hadn't heard of, but is listed on the link in Ian.M's postsupra) doesn't tell you that it contains Pluronic surfactant (contact lens cleaner), but its patent does.