Fluke 187 corroded battery terminals - how to clean?

[retiredcaps]

I bought this used Fluke 187 off ebay.  Opening up the battery compartment reveals some past battery leakage/corrosion.     The supplied batteries are not leaking and are Duracell Procell with expiry date 2017.

I have read about using baking soda and vinegar to neutralize the corrosion as per

https://www.eevblog.com/forum/beginners/electronics-cleaning-leaked-batteries/

So I applied the mix using a q-tip, but as you can see, there is still corrosion (the two middle cell holders)?  Is it just a matter of applying more of the mix over and over again?  Ideally, I would like to "soak" the entire back case overnight, but I'm afraid of damaging or staining the case.

I don't *think* the main pcb was affected by the corrosion due to the design of the back plastic casing.  I can't detect any corrison on the main board.  All the rotary functions seem to work correctly.

I want to make sure there are no long term problems as I expect this multimeter to last a long time.  I will be using nimh batteries for this Fluke 187.

Suggestions are welcome. 

PS. I tried to make the pictures decent size, but bandwidth friendly (less than 750KB total for all 5 pics).

[T4P]

I use either my tweezers to remove the corrosion or i use a scalpel (The same type Mike uses in his 'surgery' of the nike fuelband) with a sharp tip

[siliconmix]

are the connections all one kind of metal as it could be osmosis

[mikeselectricstuff]

A tootbrush can be handy for scrubbing corroded terminals, as can a fine wire brush but IME you can never completely clean it once corrosion starts, and replacing contacts where possible is a good idea for long-term reliability.

[saturation]

Once you've soaked it with vinegar then bicarb to neutralize the vinegar, and water rinse to remove the bicarb you can get almost like new results with Deoxit 5% in the USA or Cramolin in the EU.   I've seen it clean out most resistant crud off contacts and restore the base metal, as best as possible.  Regardless, after using it the connection will be as good as it can be without replacing the terminal.  How it work can be found here:

http://caig.com/


You can also use deoxit 20% which comes in a dropper bottle, the difference is only the carrier: the 5% is in a spray canister, which you tend to over apply and the 20% is manually applied and can be focused on a part.

[Excavatoree]

Forgive me for suggesting an alternative in a thread titled "how to clean?" but replacement contacts are available and are often seen on E-bay.

[WorldPowerLabs]

If I were in your place, I'd replace the contacts.  I think that would provide better reliability (one of the terminals looks only slightly corroded, but one seems pretty bad).  I have also had some luck sanding the base metal on contacts until the pitting is removed, and then replating with a small electroplating kit... but it's not worth the effort if replacement terminals are available.

[MikeK]

I've used CLR and Lime-Away.  Not sure if it was appropriate, but it worked.

[retiredcaps]

@DaveXRQ,
I managed to get the badly corroded terminal off using tweezers and I'm glad I did as you can see from the pictures (next post).  The backside was in far worse shape.

@siliconmix,
Thanks for the comment.

@mikeselectricstuff,
I ended using a toothbrush to help scrub the contacts, but has you mentioned, I cannot get it completely clean.

@saturation,
Thanks for the hint about deoxit.

@Excavatoree,
Your suggestions are always welcome regardless if they are on topic or not.

I can't believe how much the replacement parts cost.  I didn't see it in the service manual so I didn't know such parts existed.

a-fluke which seems to be the only seller of these parts doesn't ship outside the USA and has his ebay account doesn't even accept "contact seller" from non USA members.

http://www.ebay.com/itm/370609154201

@WorldPowerLabs,
My first choice would be to replace the one really bad one, but a-fluke won't ship outside USA.  I may search digikey for "compatible" ones.

@MikeK
I have both CLR and Lime-Away at home.  I don't know if they are more harmful or helpful in the long run.  While I took basic Chemistry back in high school, it was a LONG LONG time ago.

PS. I have a new respect for people like tekfan who restore all the old equipment and how much of an art + science it takes to get damaged gear to fully working condition.

[retiredcaps]

So thanks to all the helpful suggestions and comments, I ended being able to get the contacts out thanks to a-fluke's ebay auction photos.  I couldn't see the "hidden" tabs late last night and it has been cloudy all day.

I was able to get the worst corroded contact out without any damage and let it soak in vinegar for about 1 hour.  Then I neutralized it by adding baking soda and let it sit for about 30 minutes.  Then I gave it a wash with tap water (I don't have any distilled at home).

Here is the result.  Do you think it is the best I can do given the tools (vinegar, baking soda, toothbrush)?

I wasn't able to remove the other not so badly corroded contact for fear of damaging it so I left it alone and tried my best to use a toothbrush/q-tip.

PS. I have a reminder now to check my batteries in all my multimeters every 6 months.

[Fraser]

Wow ! Nice job on those contacts.

My first thought when I saw your original pictures was ....contacts are scrap !. Now that you have cleaned them they look serviceable. I have been faced with similar corrosion challenges and have sometimes managed to remove the corroded material using a fibre glass pencil. These are commonplace on ebay and are stated as being a relatively gentle and very controlable abrasive. The bad news is that, as an abrasive, plating can be further damaged if care is not taken. Its worth having one in the tool box though :-) Castle Blocks aka  Garryson Garryflex Abrasive Blocks are also good to have around. They come in various grit ratings and the finest grits are great for PCB and contact cleaning. They are rubber like and behave a little like an abrasive pencil eraser.

Well done for recovering those contacts so well.

Aurora

[G7PSK]

I have always found that plain soap and water removes battery deposits. If the terminals are to far gone I cut them from thin stainless steel sheet or wind them from spring wire.

[WorldPowerLabs]

Retiredcaps, those contacts look fantastic -- good work!

[Amarbir[Lynx-India]]

So thanks to all the helpful suggestions and comments, I ended being able to get the contacts out thanks to a-fluke's ebay auction photos.  I couldn't see the "hidden" tabs late last night and it has been cloudy all day.

I was able to get the worst corroded contact out without any damage and let it soak in vinegar for about 1 hour.  Then I neutralized it by adding baking soda and let it sit for about 30 minutes.  Then I gave it a wash with tap water (I don't have any distilled at home).

Here is the result.  Do you think it is the best I can do given the tools (vinegar, baking soda, toothbrush)?

I wasn't able to remove the other not so badly corroded contact for fear of damaging it so I left it alone and tried my best to use a toothbrush/q-tip.

PS. I have a reminder now to check my batteries in all my multimeters every 6 months.

Well,
 i Have a observation to make ,Once This thing is done it again pops up .The terminals again corrode automatically .I have seen this in my scopemeter fluke .I will create a different thread for that today .

[LEECH666]

Maybe you can anodize the contacs somehow to keep then form rusting again.

I was going to suggest an fibre glass pen too, but Aurora already beat me to it.

If you can't get the whole contact out, why don't you remove the back case of the multimeter and drop it in vinegar completely?

Florian

[Excavatoree]

@Excavatoree,
Your suggestions are always welcome regardless if they are on topic or not.

I can't believe how much the replacement parts cost.  I didn't see it in the service manual so I didn't know such parts existed.

a-fluke which seems to be the only seller of these parts doesn't ship outside the USA and has his ebay account doesn't even accept "contact seller" from non USA members.
http://www.ebay.com/itm/370609154201

I'm sorry, I didn't realize he didn't ship outside the US.  (Not even to Canada?)   I've had to break down and pay his prices for some things, as sometimes he has stuff I can't find anywhere else.

I was hoping I could help you out more, but after a search for my  "parts bin" and the 180 case I thought I had, I discovered my 180 series contacts are not in good condition.  I have one or two of the "bridge" clips that are in good condition, but my positive and negative contacts are corroded about as yours are.   You're welcome to them, if it will help.   

Also, I have tinned contacts that were worn to the copper with solder - I won't recommend that before finding out what our other members think. 

[retiredcaps]

I'm sorry, I didn't realize he didn't ship outside the US.  (Not even to Canada?)

His account is setup not even to accept emails from Canada.

I've had to break down and pay his prices for some things, as sometimes he has stuff I can't find anywhere else.

With his prices and if I had to replace all 5 battery contacts, it would be over $50 USD.   

I may have found a solution.  Check your PM in a few minutes.

Yes, I'll share the solution if it works and after I have personally tested it with hopefully the help of Excavatoree.

[Firetank]

Since i was redirected to this topic and i am reading how hard is to get these contacts outside US, i am thinking maybe if you could find a friend via internet who lives in the US and will buy these for you and then re send them to you in your country. Ok i understand that you need to pay for dual postage but if really in need i think this could work..

just my 2 cents