Deoxit D100L on Gold Contacts

[TomKatt]

My vintage HP scope has some dirty switch contacts.  I’m fairly sure the switches have gold contacts, but over 50+ years grime has built up.  I know that Deoxit has a special gold formula, but all I have on hand is the red stuff.  Will the red D100L harm gold contacts?

[coppercone2]

I think basically it is more aggressive towards corrosion so if there is corrosion under the gold it can get under mined. Wheras, if you leave that corrosion alone, the gold on top remains conductive and it might be ductile enough to work in that state so long its on top of something

gold contacts are usually low current

I believe its kind of like chrome, where you get flakes. Imagine a microscopic flake thats 90% on copper and 10% on corrosion. It will stay intact. But if that corrosion under neath is removed, parts might fall off. Chrome is also incredibly resistant to corrosion, kind of like gold. Not as good, but its still a damn good metal.





Because the gold does not really decay. It just get displaced or grinded off by the contact. But it stays together like a concrete platform. So long its one piece and flat enough, the low current will have no problems going through there, regardless if some of it is supported underneath by oxide instead of metal.

Now if the oxides get undermined, you might have it try to 'fall into' the hole under neath from dissolved oxides (like if you sat on your bed and the middle was missing). This might get the bed sheet to get dislodged from around the mattress.




Thats my guess. There might be a different or additional reason


If you apply deoxit red to bad stuff, after 6 months you are left with some green crystals you can wipe away. Like petrified BNC connectors



I would just buy gold, because those switches will eventually cost you an arm and a leg if they go.....

[tggzzz]

Tektronix specifies the technique required for their wretched 4x5 attenuator contacts. Put IPA on a piece of smooth paper, insert under the fingers, close the contacts trapping the paper, and pull gently ensuring the contacts aren't bent.

I've only got experience with one HP scope (a 1740), which has different contact arrangements. Nonetheless, similar techniques seem advisable.

[nctnico]

I'd start with alcohol to clean the contacts. In my experience contact sprays make equipment work for a couple of weeks and after that you can throw it away because the acid from the contact spray has eaten away the good parts as well.

If cleaning with alcohol doesn’t work, the only option is to replace a pot or switch. You can't make a pot or switch to become un-worn.

I had some very nice vintage equipment which was destroyed by the previous owner using contact spray.

[TomKatt]

Thanks all for the feedback.  Yes, I was concerned about potentially eating away under the gold as well.  I'll try basic IPA first and go from there.  As typical, many of these contacts are a bit buried and the paper technique is not easily done because of access - but perhaps I can get in there with some forceps or tweezers.  I'm sure if I attempt to move parts around to access the contacts I'll cause more problems than I already have.

[TERRA Operative]

I have the 3 flavours of Deoxit in some Hakko flux pens. Makes for easy application.

I use the different types as per the manufacturers recommendations, but sometimes use the red stuff on dirty gold contacts to good effect so far.

[Wallace Gasiewicz]

Rather than writing paper, the old timers would use a dollar bill as it is really not paper but closer to cloth and allegedly less abrasive.

[TomKatt]

Rather than writing paper, the old timers would use a dollar bill as it is really not paper but closer to cloth and allegedly less abrasive.

I use card stock (or business cards) when I work on old EM pinballs and it works very well.  But many of these multiple contact switches on the attenuators and such on my scope are pretty buried with no good way to use that method, which is why I was hoping for a chemical solution (pun intended).

[Buriedcode]

I hate Deoxit, but I won't start a rant/flame war on this.

Whilst I've used IPA + bit of paper towel wrapped around tweezers to *gently* wipe contacts - the paper towel provides light abrasion - I usually end up using Servisol super 10.

I don't know whats in it, or if its "safe" on certain plastics or phenolics on older equipment, but it evapourates quickly, doesn't leave a residue, doesn't make phenolic boards swell, and leaves the bit of paper towel black, and the contact shiney.  My can has been with me since the 90s.

[BrianHG]

10 years ago, I used MG Chemicals Super Contact Cleaner (Poly Phenyl Ether).  The slider volume controls only needed 1 spaying and they have lasted the past decade.

Once in a blue moon (like over a year or so...), I use it on my headphone jacks to get rid of contact noise.  The gold still remains on the plugs.
(Note that I plug in and out my headphones on a regular basis and the plug come into contact with my body sweat as they are used for my fitness workout routine every other day.)

https://www.amazon.ca/MG-Chemicals-Contact-Cleaner-Aerosol/dp/B001U3X3PA?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A3DWYIK6Y9EEQB

I don't know what deoxit is but from what is said above, maybe I will never use it.
The MG Chemicals super cleaner completely evaporates after an hour or 2.

[thm_w]

The two cleaners mentioned above are variations of solvent + lube (MG contact cleaner and Servisol). Should be safe for almost any switch or pot.

Deoxit D100L ingredients:
a) Difluoroethane 75-37-6 90%
b) ProGold Non-hazardous 10%
c) DeoxIT Non-hazardous 10%

They don't explain what these ingredients are. But it looks like D series is much harsher, in this other PDF they say it has "20% cleaning" compared to Deoxit gold which is "0.1% cleaning": https://acct113328.app.netsuite.com/core/media/media.nl?id=1731&c=ACCT113328&h=39a7ad1dcf8b316671a7&_xt=.pdf&ck=QtTTQYvwAKycnqR_&vid=QtTTQYvwAOKcntex&cktime=1579

So I would be tempted not to use it.

[coppercone2]

I don't think there are too many high pressure gold contacts. With other materials, you often get extreme pressures at the connector complete with plow marks in nickel or other hard platings. So really, so long the surface is clean and the cracks in the plating are covered to prevent further corrosion (i.e. displacing moisture in fissures with protective oil), the gold contact will last a long time. It bearly has any surface corrosion.


However, I think red might still be useful for the "would be nice if the gold was still there" contacts. If you inspect it, and the area that is being mated has all the gold worn off, its not doing anything anymore, and you might as well try cleaning the under material with deoxit red. Unless you reposition a contact, the remaining gold is basically cosmetic, and the only way the device is gonna work is if you let the substrate do the work (limited mating cycles) after cleaning.



What I think the 0.1% cleaning does, is for say worn contacts, you might be getting into some kind of intermetallic substance in some cases with gold diffusion into cracked nickel under plate that becomes part of the contact surface when it gets partially worn. It might be pretty non reactive but reactive compared to pure gold.


There is also the weird phenomena that I have seen before i.e. if you get iron filing on aluminum, after a while it seems that the rust kinda grows into it if its in a humid area. After A while you can't sweep them off, it requires some minor sanding and repolishing.  I wonder if environmental contaminants can grow into gold like that.

[EPAIII]

I have an inexpensive VOM that did not work well due to bad contacts on both the power and the function switch. I opened it up and sprayed with DeoxIT D5 around two years ago and it has worked well ever since.

But I doubt that the contacts are gold.

[TomKatt]

The two cleaners mentioned above are variations of solvent + lube (MG contact cleaner and Servisol). Should be safe for almost any switch or pot.

Deoxit D100L ingredients:
a) Difluoroethane 75-37-6 90%
b) ProGold Non-hazardous 10%
c) DeoxIT Non-hazardous 10%

They don't explain what these ingredients are. But it looks like D series is much harsher, in this other PDF they say it has "20% cleaning" compared to Deoxit gold which is "0.1% cleaning": https://acct113328.app.netsuite.com/core/media/media.nl?id=1731&c=ACCT113328&h=39a7ad1dcf8b316671a7&_xt=.pdf&ck=QtTTQYvwAKycnqR_&vid=QtTTQYvwAOKcntex&cktime=1579

So I would be tempted not to use it.

I know the 'cleaning' agent is likely some acidic chemical intended to dissolve oxidation.  The red 'D' series has 20% of this active 'cleaner' and the yellow 'Gold' series has a fraction of that (I think 0.5%), which makes sense because gold does not chemically tarnish.  The Gold series also has some kind of sealer or protective lubricant in it.

I've used the red D100 on regular contacts for many years and never had any issues - it works very well imo.  But I found someone who has the Gold series cleaner and will use that because better safe than sorry.  I'd forego all the chemicals and do a manual cleaning if I could access the contacts, but they are really buried.

On a side note, I also have a can of the Fader series cleaner that I use on pots - works wonders and I haven't noticed any adverse effects afterwards.

[tooki]

I'd start with alcohol to clean the contacts. In my experience contact sprays make equipment work for a couple of weeks and after that you can throw it away because the acid from the contact spray has eaten away the good parts as well.

Check the technical data sheet or instruction manual for the contact cleaner: some of them explicitly say that they need to be flushed away afterwards. (For example, the venerable Kontakt 60 is supposed to be rinsed off with Kontakt WL afterwards, then lubricated/protected with Kontakt 61.)