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Battery corrosion help


b1807

Question

I have gone to change the batteries in my Stern AP and found the dreaded corrosion.

I have removed the battery holder.

Two questions-  can I replace the old 3 battery holder with anything else, or is it like for like?

and, how do I treat the corrosion? 
 

the machine has been working fine 

 

thanks 

 

8E2E5E3C-0F87-4E5C-811C-064E1D6493A6.jpeg

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Get rid of the battery holder and change the sram to an NVRAM. I sell them as does tangles.

 

Clean up the corrosion. Use some bicarb soda and water to neutralise the acid, then thoroughly clean the area and use alcohol if you have some to remove any residue. Ideally tin the tracks that have been tarnished. A fibreglass pen is great for polishing the tarnish from the tracks if its too badly tarnished to solder. And finally if you really want to go the extra step, cover the traces again with a mask such as https://www.chemtronics.com/circuitworks-overcoat-pens which can be bought from many different places online.

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1 hour ago, cwispy said:

Get rid of the battery holder and change the sram to an NVRAM. I sell them as does tangles.

 

Clean up the corrosion. Use some bicarb soda and water to neutralise the acid, then thoroughly clean the area and use alcohol if you have some to remove any residue. Ideally tin the tracks that have been tarnished. A fibreglass pen is great for polishing the tarnish from the tracks if its too badly tarnished to solder. And finally if you really want to go the extra step, cover the traces again with a mask such as https://www.chemtronics.com/circuitworks-overcoat-pens which can be bought from many different places online.


Don’t you want to use an acid to neutralise the alkaline?

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13 hours ago, b1807 said:

I have gone to change the batteries in my Stern AP and found the dreaded corrosion.

I have removed the battery holder.

Two questions-  can I replace the old 3 battery holder with anything else, or is it like for like?

and, how do I treat the corrosion? 
 

the machine has been working fine 

 

thanks 

 

8E2E5E3C-0F87-4E5C-811C-064E1D6493A6.jpeg

You're very lucky 🙂 I'd call this minor and believe me I've worked on some bad ones.

As long as the sockets haven't been damaged I'd just install a FRAM and enjoy the game.

 

 

PXL_20211229_070003465.jpg

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16 hours ago, cwispy said:

Clean up the corrosion. Use some bicarb soda and water to neutralise the acid

The way you've written this it sounds like you've said "use bicarb to clean up the battery acid". 

So for clarity, alkaline battery damage is alkaline. You need an acid to neutralise it. Vinegar should be fine. I usually wouldn't bother using bicarb after, I'd just use isopropyl to clean it after the vinegar.

As @ocyensaid, you want to sand too.

It might seem a bit "belt with braces" but I use both so that things I can't sand like the vias have a chance of being ok. Don't forget the reverse side of the board.

 

Edited by ajfclark
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16 hours ago, ocyen said:

Go at it with sandpaper until the traces are shiny like new. Then, tin or mask to protect. You can neutralise too, but the sandpaper will get rid of everything in one go.

Please do not use sandpaper. Use a fibreglass pen or if you do not have one of them, at a pinch you can use a scouring pad such as a scrotch-brite pad. They are not as effective by any means. Sandpaper will remove more than the tarnish as well as damage the substrate.

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8 hours ago, Arcade King said:

You're very lucky 🙂 I'd call this minor and believe me I've worked on some bad ones.

As long as the sockets haven't been damaged I'd just install a FRAM and enjoy the game.

 

 

PXL_20211229_070003465.jpg

Looks like a T2 mpu board I had to do many moons ago. Become a "your not beating me" project in the end but I did win.

While some like to sand and make it look better I prefer to just neutralise the corrosion and check with a meter if the trace is still intact. Many times it is but sometimes no so out comes the Kynar wire if the trace is stupidly thin or the "conductive pen" when the trace is better suited.

Best to discribe what a conductive pen is using there words....

A common method of repairing a broken trace is to solder on a jumper, which is basically a wire bypass around the broken trace. This can be time-consuming and visually unappealing. Chemtronics offers CircuitWorks® Conductive Pens, which contain a highly conductive material like silver or nickel suspended in a liquid polymer. These pens allow you to literally redraw the trace.

Either way you choose to do the repair, just rememeber while boards hate corrosion, they also hate flexing so I figure sometimes it best just to neutralise and repair with these two methods rather than stressing the board trying to make it look like it did.

If the trace is broken and your using the Kynar wire method follow the trace to a solder point on the trace and solder to that rather than trying to clean a trace for soldering. Far less stress on the board than trying to clean a corroded trace. Run the Kynar wire directly over the old trace and dots of clear nail hardener drys fast and holds the wire to the board.

Many ways of doing these repairs but I figure if I am less stressful on the board, a better chance of having no unrelated problems elsewhere on the board to fix.

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On 21/01/2022 at 4:38 PM, cwispy said:

Please do not use sandpaper. Use a fibreglass pen or if you do not have one of them, at a pinch you can use a scouring pad such as a scrotch-brite pad. They are not as effective by any means. Sandpaper will remove more than the tarnish as well as damage the substrate.

Hi Shane, keen to know more about this. What kind of damage does it do? Never had an issue myself, but I tend to sand just until I hit the copper of the trace and then stop. Sure it does sand some of the board substrate away but is that a big issue? I use a fibreglass pen occasionally but find it doesn't quite have the same "bite".

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I had a Stern MPU-100 board I sent to Becky with corrosion, Man what a beautiful job he did on that board. De-corroded, repaired & new lacquer. Board came back like new! Worked 100% perfect too.

Also something about water.... Today,  it's not neutral (7.0ph) most tap water is slightly acid, best use distilled water for any board rinse.

Edited by Gemini2544
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11 hours ago, ocyen said:

Hi Shane, keen to know more about this. What kind of damage does it do? Never had an issue myself, but I tend to sand just until I hit the copper of the trace and then stop. Sure it does sand some of the board substrate away but is that a big issue? I use a fibreglass pen occasionally but find it doesn't quite have the same "bite".

Glass paper can leave debris behind. Maybe that's the problem?

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On 22/01/2022 at 6:10 PM, ocyen said:

Hi Shane, keen to know more about this. What kind of damage does it do? Never had an issue myself, but I tend to sand just until I hit the copper of the trace and then stop. Sure it does sand some of the board substrate away but is that a big issue? I use a fibreglass pen occasionally but find it doesn't quite have the same "bite".

One of the first things to keep in mind is that some board substrates, when sanded, will give off very nasty particles that if breathed into the lungs can cause Silicosis in the most severe of situations. There is no cure for Silicosis. Other board substrates can suffer insulation breakdown because of the removal of substrate, even very light removal. Although its unlikely for a board such as this, it is not a practice that should be encouraged due to the fact that too many people who do not know what they are doing, read these types of forums, and end up thinking that its the best fix when it probably isn't.

The second problem is the copper trace itself. Depending on how the board was manufactured, the copper could be multi-layer with different grades of materials used, so sanding can remove way too much material. It is pretty unlikely on these types of boards, but again, it is something which should be discouraged.

Another option for removing tarnish is to use rubber polishing/buffing wheels for a dremel type tool (at low speed and light pressure). These can be used to slowly polish away the tarnish, without damage to the board.

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Anyway. Problem solved. I took the quickest (to me) solution and placed a new battery pack way off to the side away from everything. 
will look at the fram solutions as a longer term solution. 
Thanks for the ideas. 

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