Coroded Electrical Contacts Restore

Electronic flash has corroded electrical contacts. Duracell AA batteries leaked. The contacts are molded into a plastic holder and cannot be easily removed. I have cleaned the metal contacts using a diamond tip. I did this a few months ago and the contacts re-corroded. Again cleaned but what can I do to retard corrosion? Some in place coating or plating?

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Reply to
OldGuy
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They have an anti-corrosion spray for car battery terminals. Clean the terminals via what is easiest, spray some of the anti-corrosion on some q-tips and rub on contacts.

If possible remove all pits from contacts since this tends to enhance corrosion regardless of treatment. Filling and shaping with solder might be an option if damage to other parts of the device will not occur. Tricky, so this might not be an option.

Reply to
Nightcrawler®

Copper contacts?

Grease. Any type that excludes oxygen and water. Keep those out and the copper won't corrode. Yeah, it's messy, but how often do you change the batteries?

Bright electroless tin will inhibit corrosion. You won't like the price: Hot tin plating is cheaper and better, but messy.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

Remove the corrosion with vinegar or acid (ammonia) based window cleaner. Put it on with a Q-Tip, let it sit and wipe it off. DO NOT spray it with anything, including those things sold as contact cleaners.

Once the corrosion is visbaly gone, you can use a real contact cleaner, such as Cramolin or DeOxit liquids. Again, a little bit on a Q-Tip, wipe it off with a dry one.

There are electronic contract enhancing compounds that can be applied sparingly to help it work. Someone else mentioned the ones used for car batteries, but that IMHO is using a sledge hammer where a gentle tap is needed.

More suitable to general electronics is Stabilant-22 (very expensive), or DeOxit makes one for gold plated contacts and one for non gold contacts.

You can buy a kit containg DeOXit, cleaner, contact enhancers, and fader lube (for lubricating variable resistors) for under $20, it will last for many years use by the average person.

Not appropos to the original question, I have rescued many bad volume controls with a drop of DeOxit and a drop of Fader Lube.

Whatever you do, DO NOT USE A SPRAY.

Geoff.

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Geoffrey S. Mendelson,  N3OWJ/4X1GM/KBUH7245/KBUW5379
Reply to
Geoffrey S. Mendelson

Ammonia is an alkali, not an acid. I've used household ammonia for years, and never had problems. Once the contacts were cleaned, they stayed clean.

There are disagreements among us as to whether Energizers or Duracells are more likely to leak. Every modern battery that has leaked in my equipment has been a Duracell. I don't use them, unless they're the only batteries available.

Reply to
William Sommerwerck

Warning! "Fader Lube" doesn't work on all linear attenuators. It can make some of them worse, as in stuck. Ammonia is an alkali, higher than normal pH.

Duracell makes very crappy batteries. "The worse the product the better the ad campaign." Sennheiser now ships with Energizer. Fry's house brand batteries leak less than Duracells.

Reply to
dave

Hey! Hammers fix everything! :-)

Reply to
Nightcrawler®

What is in that spray and how does it work? I have some that I use on car batteries. I would think that it would insulate the cell from the contact.

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Reply to
OldGuy

Wax or plastic coating, dissolved in various organic solvents.

For example, CRC "battery terminal protector" spray.

63.5% of the contents are organic solvents and propellent: CAS number Chemical name Common name and synonyms % 68476-86-8 Liquefied Petroleum Gas 20 - 30 64742-49-0 Naphtha (petroleum), Hydrotreated Light 20 - 30 589-34-4 3-Methylhexane 10 - 20 142-82-5 n-Heptane 10 - 20 8009-03-8 Petrolatum 10 - 20 591-76-4 2-Methylhexane 5 - 10 108-87-2 Methylcyclohexane 5 - 10 64741-88-4 Distillates (petroleum), Solvent-refined Heavy Paraffinic 1 - 3 1330-20-7 Xylene 1 - 3 100-41-4 Ethylbenzene < 1 110-54-3 n-Hexane < 1 The rest is probably some form of acrylic plastic or wax, dissolved in the above solvents, which coats the terminals. Anything that resists water, gasoline, grease, oil, and battery acid attack, will work. Add some red dye so it can be easily seen. The solvents are needed to clean the terminals, remove engine grease, and help the plastic or wax to stick to the battery terminals.

Nope. As long as the wax or plastic coating is sufficiently soft, the clamping pressure of the battery clamps or screws will push the coating out of the way and provide a good connection. If the coating were something quite hard, it might be a different story, but not with a soft coating. I just notice the that the CRC data sheet shows: "Provides a lead-free soft protective coating." Note the "soft".

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

Why? What's wrong with various cleaners in spray cans (besides the overspray making a mess)?

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

They tend to damage the things you are cleaning. Many of them dissovle plastics. Many of them casuse the wafers in wafer switches to expand and crack.

Geoff.

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Geoffrey S. Mendelson,  N3OWJ/4X1GM/KBUH7245/KBUW5379
Reply to
Geoffrey S. Mendelson

OK. Do you think it's the propellent in the can that's causing the damage? I presume everything else in the formulation is the same with cleaners in a spray or bottle container.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Odd. Usually the cleaning is done, the termination is made, then the protective coating is applied.

Reply to
Nightcrawler®

AFAIK it's the cleaners too. DeOxit must be carefully applied and removed.

Geoff.

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Geoffrey S. Mendelson,  N3OWJ/4X1GM/KBUH7245/KBUW5379
Reply to
Geoffrey S. Mendelson

formatting link

John :-#)#

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(Please post followups or tech inquiries to the newsgroup) 
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Reply to
John Robertson

Agreed and my apologies for the topic drift. The original question was about AA batteries in an electronic flash. The question by "Old Guy" was if an automotive battery terminal protector was suitable. My best guess(tm) is maybe. I answered without making any distinction between the two questions.

Apply after connection is the recommended method and the way it's commonly done with automobile batteries. One does not want any extra glop between the lead battery post and lead battery terminal. I have one of those wire brush battery post/terminal cleaning tools for the purpose.

However, I have done it the wrong way (when I was in a hurry, not paying attention, distracted, clueless or all the aforementioned) without ill effects. It worked because before clamping down on the terminal locking nut, I rotated the terminal on the battery post back and forth a few times to clean out the red stuff. It worked and no problems.

However, the OP was asking about AA batteries in an electronic flash, which doesn't have enough clamping pressure to clean out the wax or plastic coating at the points of contact. Try to use automobile type battery terminal protector on a AA spring loaded battery contact, and there *MAY* be a problem, especially if a thick layer is applied. I've successfully used grease and wax (furniture polish) to "protect" battery contacts, mostly in flashlights. If I get a lousy contact, I just spin the battery in the flashlight or holder. The flashlight works until the grease or wax creeps into the connection again. I use white lithium grease mostly because I have a large supply. Anything that doesn't evaporate should work.

However, if the idea is to inhibit corrosion without coating the terminals, I again suggest electroless tin to protect the exposed copper.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

No biggie, and I understand what you were stating.

Reply to
Nightcrawler®

The cotton tip swab is your friend. Does anyone have any Davenol?

Reply to
dave

Ordinary spiraled spring-type replacement contacts are available from variou suppliers. Original contacts are generally made from steel, then plated with copper and nickel or possibly a chrome-like plating.

Many repairs require disassembly as leaking chemcas can wick into power leads, which will often result in a chronic corrosion problem, even if the contacts are cleaned, or the power leads might simply continue to rot.

If corroded contacts can't be thoroughly cleaned or are too far gone, fabricating new contacts from nickel may be a worthwhile, more permanent repair. Nickel (round) wire is available a german silver wire for making jewelry, and flat nickel available in strips or coils/rollls for strapping rechargeable battery cells together to make battery packs.

Nickel easily accepts solder allowing power leads to be attached.

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Cheers, 
WB 
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Reply to
Wild_Bill

Probably the little springs are steel, with a bright nickel or chrome plated coating (sometimes copper). If the plating has come off, your best replacement would be... solder.

Clean, flux (an acid flux, like for stainless steel, works best) and then tin the spring's contact end with a soldering iron, using tin/silver solder. Then, of course, rinse the area (to get rid of the flux). Steel isn't a great conductor of heat, a second or two with the soldering iron won't melt the plastic.

Reply to
whit3rd

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