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Cleaning the corrosion after a leaky battery


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I am trying to save the life of a Seiko quartz. I think the coil is dead but the board looks ok. I have tried cleaning it with some bicarbonate of soda mixed into a paste. It has helped but there are still signs of the greenish stuff left over. I don't want to be too aggressive in case I damage the circuit. Should I just give it another treatment until it is all gone or does anyone have another method I could try.

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6 minutes ago, oldhippy said:

Come on chaps only one reply Davey57 needs more suggestions. Davey57 I can't help I never did quartz repairs I hated the blighters.

Well on quartz movements the two components that are responsible for 99% of failures are coil and circuit board. The first is easily diagnosed as mentioned above, which by exclusion only leaves the other. It's not much a matter of suggestions but to follow a flowchart. 

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I don't think you should clean the coil with bicarbonate :) . I think you mean cleaning the circuit board. And as long as you don't destroy the circuits it will work fine. I have used a glassfiber brush to clean the board from green stuff? Without any problem. If it's a circuit board like on the 7T32 i would clean with some alcohol solvent . All depends how the circuit board looks.

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1 hour ago, jdm said:

Measure the coil resistance to know it it's faulty. On electronics it's not the looks of it that matters.

Yes that's very true, I shouldn't make assumptions. The only tester I have is one of those quartz 4 in 1 testers, it has the facility for testing continuity and it  shows there to be no continuity. I imagine a good meter would be a more reliable way to make a diagnosis (another tool to add to the list). I have read about some people favoring analogue meters as opposed to digital  for testing quartz watches, is there anything in it before I purchase one?

As for the corrosion, the bicarb has cleaned the heavy deposits from the board and it looks ok but there is some slight staining left behind, the mainplate also has some staining but I can be a bit more aggressive cleaning that. I lightly brushed the deposits from the coil but it has a dull look to it where it has been attacked.

The corrosion has the same appearance as we used to find on the truck battery terminals and it could rot it's way through heavy duty terminals and battery posts. We used to wash it off with boiling water and it came up sparkling clean, don't fancy trying the same method in this case though.

I found this document that might be useful. It lists the values for testing coil resistance.

battery-no-cross-reference-chart.pdf

 

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3 minutes ago, Davey57 said:

Yes that's very true, I shouldn't make assumptions. The only tester I have is one of those quartz 4 in 1 testers, it has the facility for testing continuity and it  shows there to be no continuity.

Diagnosis is then completed with fault found. Regarding the circuit board all you want is to clean the contact pads, which is not difficult to achieve.

Edited by jdm
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When cleaning quartz circuits you only want to try cleaning the circuit contact points, there's no point in cleaning anything else and in fact you run a risk of damaging components doing so.

There's only two methods I ever really used (not like it's something I have to do everyday) that is a swab with a small amount of isopropyl alcohol (which i'll point out is used in the electronics industry for cleaning circuit boards) 
Then secondly by scratching the corrosion off, you can carefully scrape at the contact points with a screw driver blade but probably better you use something that doesn't actually damage the contact metal, so ideally you'll want to get a set of these abrasive pens. There are very effective and very safe for this purpose. 

(worth noting both the abrasive pens and iso alcahol can be picked up very cheaply and make good additions to your toolkit/supplies.)

Edited by Ishima
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Most of the circuit was affected by the corrosion, I thought it would be policy to clean it off. If left would it not eventually destroy the metal, or is it not active after it has dried?

As mentioned above is not like cleaning can fix a faulty circuit board. But if you insist " cleaning" corrosion on a trace you can end cutting it for good.

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I understand that cleaning it off is not going to fix it. But if you leave the crud and corrosion is it not eventually going to rot through the circuit eventually anyway?  There was so much of a deposit that to check the circuit was still intact I had to remove the deposits somehow. The bicarb softened the stuff and I was able to gently dislodge it with a tiny piece of pegwood until I could actually see the metal of the circuit. Turns out that it wasn't cut through anywhere. The contact points themselves were not affected by the corrosion.  I just wanted to know if there was a less harsh method to remove the remaining stains. Sounds like I should be satisfied with it the way it is.

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I guess it depends a lot on the context, usually when you discover battery leakege it's been like that for a number of weeks, right? I would assume the chemical reactions that take place already have. And every chemical has a finite amount of reactions, You put lithium in water and it will catch on fire and burn out, it won't keep going forever, that's basically true of everything. 

I guess you could make the exemption that the corrosion could make an electric short, joining two parts that shouldn't.

going back to those abrasive pen brushes, if you really want to clean a circuit thoroughly, chances are you can do so with the fiberglass pen without damaging the components, though I don't think i'd ever try that (or anything) on the coil.

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Wish I'd taken a photo to give a better idea of what I was looking at. It looked as if the watch had been left in this state for months on end if not longer, I bought it as a non runner.

I have a couple of fibre glass pens, but I like the set you pointed out. So more will never come in wrong:)

Thanks for the help everyone.

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If the leaky battery was alkaline, you need to use spirit vinegar to clean up the green stuff  - be judicial and use a stiffish brush (old tooth brush is good) - do not scrape as said above. Finally, rinse with water and then flush thoroughly in IPA (the alcohol not the beer :) ). With the green stuff away, you will be able to examine the PCB tracks - it is possible one or more will have been eaten through - can be repaired with care - use modeler's masking tape to protect the rest of the PCB then solder in place a wire filament (extracted from any old bit of 10 amp multi-strand flex) - will need a pencil iron @ 12w and 0.5 cored solder (I use a gas iron - find the freedom of the absence of a flex a great help)

Edited by presto0906
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1 hour ago, presto0906 said:

If the leaky battery was alkaline, you need to use spirit vinegar to clean up the green stuff  - be judicial and use a stiffish brush (old tooth brush is good) - do not scrape as said above. Finally, rinse with water and then flush thoroughly in IPA (the alcohol not the beer :) ). With the green stuff away, you will be able to examine the PCB tracks - it is possible one or more will have been eaten through - can be repaired with care - use modeler's masking tape to protect the rest of the PCB then solder in place a wire filament (extracted from any old bit of 10 amp multi-strand flex) - will need a pencil iron @ 12w and 0.5 cored solder (I use a gas iron - find the freedom of the absence of a flex a great help)

No need to do anything of that because in this cause the coil is known to be faulty:

Quote

The only tester I have is one of those quartz 4 in 1 testers, it has the facility for testing continuity and it  shows there to be no continuity.

 

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Thanks for that info presto0906.

Luckily the circuit is still intact. I will certainly give your suggestion a try if I am not so lucky the next time.

When you say spirit vinegar would that be white vinegar as opposed to the stuff you put on fish and chips? I have a good supply of IPA, the beer not the alcohol, and was much relieved to read that I did not have to waste any on cleaning watch parts:)

 

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Yes just white vinegar - don't often come across acid electrolyte batteries these days but for leakage from them, you would apply moist soda-carb powder (sodium carbonate) - and brush off after

Edited by presto0906
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