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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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I got an old AM-FM pocket transistor radio which looked good and clean
till I opened the battery compartment. Very corroded carbon zinc batteries were in it. After removing them, I cleaned off as much of the corrosion as possible by scraping with a plastic stick, and scrubbing with q-tips and rubbing alcohol. That got rid of most of it, and I was surprised to find the battery clips are not badly damaged, but I had to use a fingernail file (sandpaper strip) on the ends of the springs. Better yet, the radio works perfectly. But there is still a little of that battery corrosion still in there. In all the years I've worked on electronics, I have never found a perfect way to clean up leaked batteries. Is there some sort of spray or a chemical that will dissolve or deactivate that crap? Of course it has to be safe for the circuit board and components too. I use the 91% isopropyl alcohol, so it evaporates quickly and leaves little water residue behind. (Then leave it dry well before use). |
#2
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On Sunday, February 11, 2018 at 5:53:57 AM UTC-5, wrote:
I got an old AM-FM pocket transistor radio which looked good and clean till I opened the battery compartment. Very corroded carbon zinc batteries were in it. After removing them, I cleaned off as much of the corrosion as possible by scraping with a plastic stick, and scrubbing with q-tips and rubbing alcohol. That got rid of most of it, and I was surprised to find the battery clips are not badly damaged, but I had to use a fingernail file (sandpaper strip) on the ends of the springs. Better yet, the radio works perfectly. But there is still a little of that battery corrosion still in there. In all the years I've worked on electronics, I have never found a perfect way to clean up leaked batteries. Is there some sort of spray or a chemical that will dissolve or deactivate that crap? Of course it has to be safe for the circuit board and components too. I use the 91% isopropyl alcohol, so it evaporates quickly and leaves little water residue behind. (Then leave it dry well before use). My sovereign cleaning method for this is to use a very strong concentration of baking soda mixed into distilled water. About a tablespoon of soda into a teaspoon of water to make a paste. This will neutralize any corrosives from the batteries - but the material is highly conductive in its own right. So, after application with a small toothbrush or spiral brush, rinse again as yo have with distilled water, then alcohol to displace the water. If severe, and the alternative is landfill - I have been known to run an entire chassis through the dishwasher (one without an exposed Calrod), or use a bit of lye-based oven cleaner on a cotton swab - again rinse carefully when done. Needs must when the devil rides. Peter Wieck Melrose Park, PA |
#3
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#4
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Ralph Mowery schrieb:
[...] As most of the batteries used in portable devices are some type of alkaline the baking soda is the opposit of what should be used. White vinegar is what you should be using to neutralize it. Full ack! Regards Reinhard |
#5
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On Sunday, February 11, 2018 at 10:23:41 AM UTC-5, Ralph Mowery wrote:
As most of the batteries used in portable devices are some type of alkaline the baking soda is the opposit of what should be used. White vinegar is what you should be using to neutralize it. I am not sure what the very old carbon zinc batteries used, it may have been a from of acid. I know the car batteries use acid and the baking soda is good for that. Just not good for the newer smaller AA,C,D type batteries. LeClanche cells are acid-based (Ammonium CLoride) with an acidic pH (depending on the age of the cell) from about 6 (nearly dead) to about 4.6 (fresh). Hence the pointer to baking soda. Baking Soda (Sodium Bicarbonate) is about pH 8.4 when dissolved in water. Household vinegar is pH 2.4, and will tear copper apart. The neutralizing agent wants to be slow and mild. Vinegar (acetic acid) is pretty strong. Peter Wieck Melrose Park, PA |
#6
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On Sunday, February 11, 2018 at 7:51:25 AM UTC-5, wrote:
If severe, and the alternative is landfill - I have been known to run an entire chassis through the dishwasher (one without an exposed Calrod) Back when projection TVs were plagued with coolant leaks, I used to soak the entire circuit board in an ammonia and soap solution. But *first*, everything that can trap water must be removed. Back then, that meant SMPS transformer, HOT and flyback XFRs, inductors,etc. A lot of work but it fixed stubborn symptoms and no call backs. In a transistor radio, this means removing the IF transformers, audio transformer, and even removing the gang tuner is a good idea. |
#7
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"Back when projection TVs were plagued with coolant leaks, I used to soak the entire circuit board in an ammonia and soap solution. But *first*, everything that can trap water must be removed. Back then, that meant SMPS transformer, HOT and flyback XFRs, inductors,etc. A lot of work but it fixed stubborn symptoms and no call backs. "
I had a different technique. I washed it in hot water, then alcohol, then acetone with a brush and then blew dried it on hot to evaporate everything. And then sprayed with spray solvent to make it cold. That squeezes the **** out of the board, which is quite porous. Repeated about 4 times. The last time left the acetone or alcohol on it, heated it up with the blow dryer and waited a while until you could not smell it anymore. The worst part was when it corroded the copper traces. Can't solder to them, must get all the way to the point where it is no longer dark and add a jump[er.And also extra clean that area because there is more conductive **** in it. It is actually in the board and you can see bubbles when you heat it.. I remember old AA and AB GE chassis bubbling under the solder on the gripletts which impeded their soldering. And those were about 90 % of the problems with those sets. |
#8
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On Monday, February 12, 2018 at 5:40:36 AM UTC-5, wrote:
"Back when projection TVs were plagued with coolant leaks, I used to soak the entire circuit board in an ammonia and soap solution. But *first*, everything that can trap water must be removed. Back then, that meant SMPS transformer, HOT and flyback XFRs, inductors,etc. A lot of work but it fixed stubborn symptoms and no call backs. " I had a different technique. I washed it in hot water, then alcohol, then acetone with a brush and then blew dried it on hot to evaporate everything.. And then sprayed with spray solvent to make it cold. That squeezes the **** out of the board, which is quite porous. Repeated about 4 times. The last time left the acetone or alcohol on it, heated it up with the blow dryer and waited a while until you could not smell it anymore. Seems like a lot more work than a one step soak. We received a bulletin from RCA about coolant leaks, and they suggested ammonia based detergents as the most effective way of removing the coolant and it's associated contamination. I had a PTK195 that would do all sorts of very intermittent weird things in the vertical circuit even after a regular cleaning. I found a product called Parson's Sudsy Ammonia and used that diluted in a parts washer. The board were spotless and even glossy after drying. I remember old AA and AB GE chassis bubbling under the solder on the gripletts which impeded their soldering. And those were about 90 % of the problems with those sets. My brother (the hero) used to hard wire those GEs through the griplets but I used to just solder the bottom, solder the top, then resolder the bottom again and give it a good spay of Flux-Off (the original stuff). That took less time than it might seem and they never came back. |
#9
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On Sun, 11 Feb 2018 04:51:20 -0800 (PST), "
wrote: a very strong concentration of baking soda mixed into distilled water. This makes sense, but I have to ask why regular tap water wont work V/S distilled water? I know that adding water to a car battery should be distilled, (so it dont have any minerals), but in this case, it would seem that any clean water would work. But maybe I am missing something. Yet, I do try to eliminate unnecessary expenses, and distilled water adds to the cost, not to mention an extra trip to a store, since it's not something I keep on hand. |
#11
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On Mon, 12 Feb 2018 08:38:22 -0000, Mike Coon
wrote: In article , says... But maybe I am missing something. Yet, I do try to eliminate unnecessary expenses, and distilled water adds to the cost, not to mention an extra trip to a store, since it's not something I keep on hand. What do you put in your steam iron? That's where most of my distilled/de-ionised water goes... Mike. Steam iron? Do they still use those things? I recall my mother using one in the 1950s and 60s.... Either way. blue jeans and flannels shirts dont need ironing... That's about all of us rural folks wear, aside from our camo hunting clothes. I did once hear of a guy trying to iron his birthday suit, after drinking a lot of shine.... Luckily his wife ironed his head with a cast iron frying pan before he damaged too much of his birthday suit. and she then sent him to bed. |
#12
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#13
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On Mon, 12 Feb 2018 08:38:22 -0000, Mike Coon
wrote: What do you put in your steam iron? That's where most of my distilled/de-ionised water goes... Mike. I use tap water and let the lime accumulate until I can see it. Then, a rinse the iron with 75% water and 25% white vinegar. Let the iron get hot, and push some steam through the plumbing. Also, I empty the old water from the iron between uses. https://www.google.com/search?q=how+to+clean+a+steam+iron -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#14
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It's *almost* not worth it. More than once, when the iron starts spitting out precipitate, we've thrown it away and bought a new one. I've cleaned them too, but it doesn't work 100% and pretty quickly builds up again.
We've bought new irons for as little as $12. And you get to salvage a nice heavy duty cord for another project. Distilled water does work really well of course, if you are religious about using it... at 89 cents a gallon I can't see where it adds to the cost of anything. A gallon goes a long way, in an iron or in cleaning electronics. De-ionized water is a very different animal. |
#16
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This is a vintage transistor radio, likely using a carbon-zinc battery (LeClanche Cell). They use an acid-based electrolyte. As carefully detailed. Latter-day batteries *tend* to use alkaline-based electrolytes - making most of the discussions herein accurate. But - not in all examples of all cases.
I try to advise based on good chemistry based on the data as presented. Peter Wieck Melrose Park, PA |
#17
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#18
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On Sunday, 11 February 2018 10:53:57 UTC, wrote:
I got an old AM-FM pocket transistor radio which looked good and clean till I opened the battery compartment. Very corroded carbon zinc batteries were in it. After removing them, I cleaned off as much of the corrosion as possible by scraping with a plastic stick, and scrubbing with q-tips and rubbing alcohol. That got rid of most of it, and I was surprised to find the battery clips are not badly damaged, but I had to use a fingernail file (sandpaper strip) on the ends of the springs. Better yet, the radio works perfectly. But there is still a little of that battery corrosion still in there. In all the years I've worked on electronics, I have never found a perfect way to clean up leaked batteries. Is there some sort of spray or a chemical that will dissolve or deactivate that crap? Of course it has to be safe for the circuit board and components too. I use the 91% isopropyl alcohol, so it evaporates quickly and leaves little water residue behind. (Then leave it dry well before use). I did one yesterday, got what I could off some bent flat strip with a screwdriver, got the remainder off with a grinder. A dishwasher is more often the suitable treatment, but as has been said there are some parts definitely not dishwashable. Speakers, unpotted relays, variable caps, paper caps, transformers, some other stuff. NT |
#19
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On Sun, 11 Feb 2018 04:52:51 -0600, wrote:
But there is still a little of that battery corrosion still in there. In all the years I've worked on electronics, I have never found a perfect way to clean up leaked batteries. Is there some sort of spray or a chemical that will dissolve or deactivate that crap? I use 409 spray cleaner, a plastic scraper, and a paint brush. For alkaline cells, scrape off as much of the white powder as possible. Clean what you can with the small paint brush. Then attack with the 409 spray. It will evaporate dry in about an hour. If you have an air compressor, you can blow out the excess liquid and it will dry quicker. It's been so long since I've seen any equipment that uses a carbon zinc cell, that I don't recall how it's cleaned. Probably some alkaline cleaner. The most common problem I see are corroded battery springs and contacts. Once the plating is gone, it's difficult to keep them from corroding again. Grease helps, but makes a mess. So, I replace them with similar or identical spring contacts purchased on eBay and other online vendors: https://www.ebay.com/sch/i.html?_nkw=battery+spring+contact -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#20
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#21
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On Sun, 11 Feb 2018 20:35:56 +0100, Look165
wrote: Since this layer is alcaline, the best to use an acid ; vinegar for instance. https://en.wikipedia.org/wiki/Alkaline_battery#Leaks Yep. The white stuff from an alkaline cell is potassium carbonate and has a pH of about 11 in water: https://en.wikipedia.org/wiki/Potassium_carbonate Vinegar works, but citric acid (lemon juice) smells better. If the cleaner produces gas bubbles, it's working. However, I don't think it matters much. I use 409 household cleaner which has a pH of 9 to 11.5 depending on concentration: http://www.gjfood.com/pdf/msds/79_820040.pdf It produces some bubbles, does a good job of cleaning, and smells ok. The white stuff that leaks out of carbon zinc battery is the zinc chloride electrolyte: https://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_battery#Durability https://en.wikipedia.org/wiki/Zinc_chloride Zinc chloride in water is very acidic with a pH of 2.0 to 3.0 depending on concentration. It's very soluble in water so any water based alkaline cleaner, such as houshold ammonia, should work. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#22
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On Sun, 11 Feb 2018 14:35:43 -0800, Jeff Liebermann
wrote: The white stuff that leaks out of carbon zinc battery is the zinc chloride electrolyte: Oops. Zinc chloride is the crud that leaks out of the battery. The electrolyte is ammonium chloride. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#23
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On 11/02/18 23:38, Jeff Liebermann wrote:
On Sun, 11 Feb 2018 14:35:43 -0800, Jeff Liebermann wrote: The white stuff that leaks out of carbon zinc battery is the zinc chloride electrolyte: Oops. Zinc chloride is the crud that leaks out of the battery. The electrolyte is ammonium chloride. Zinc chloride actually attracts so much water that it dissolves in it, as I found out when I tried to crystallize the stuff. Jeroen Belleman |
#24
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On Mon, 12 Feb 2018 00:31:54 +0100, Jeroen Belleman
wrote: On 11/02/18 23:38, Jeff Liebermann wrote: On Sun, 11 Feb 2018 14:35:43 -0800, Jeff Liebermann wrote: The white stuff that leaks out of carbon zinc battery is the zinc chloride electrolyte: Oops. Zinc chloride is the crud that leaks out of the battery. The electrolyte is ammonium chloride. Zinc chloride actually attracts so much water that it dissolves in it, as I found out when I tried to crystallize the stuff. Jeroen Belleman What were you trying to make? Soldering flux (usually a mix of zinc chloride and hydrochloric acid)? Don't use it on electronics as it's conductive. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#25
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