Thread
Tolerances for capacitor replacement: electronics query
You need to remove the coloured deposits, if only to be sure that traces and lands have not been severed or destroyed underneath the deposits. Better to know this at the outset than to rue it later.
Any one or more of the chemical species in the electrolyte, alone or in concert with others.
Which is what may happen if the logic or power/sweep board is powered-up or active while the capacitors are leaking.
It's a matter of concentration as well as pH. A few ppm of something such as chlorine residues (most of the hypochlorite has been reduced as it was acting on organisms or inorganic molecules) is of no consequence, even if you can still smell it. The aim of washing is 'infinite dilution' of the nasties by washing completely one, two, three or more times as needed, and then rinsing several times to reduce the concentration of nasties (which are not being replenished because you have already removed the bung capacitors) to infinitesimal levels. It's an asymptotic approach to zero, which is never reached, but can be approximated. Ordinary kitchen detergents are non-polar. If in doubt, consult the label on the container.
Last 25-odd years: Technical writer/editor. Previous 25 years: Biologist, biochemist, microbiologist, fermentation technologist, biodegradationist(?)—in industry—with a strong dabbling in electronics to use in those disciplines.... 5) Easy one: what's your profession? You know so much about capacitors, I'm lead to believe you make capacitors as your day job
Y' wulcum.
de
1)
What you say makes most sense indeed.
3)
Indeed.
4)
How about using baking power with warm water? Any comments on this?
As for non-polar detergents, I looked at the labels, but they don't say.
5)
No wonder your writs are most elequent (loved the sentence about the asymptotic approach)! Where can one find your editorials?
I was right about the mad scientist comment! Or more appropriately a panepisteme, or the term I prefer for myself sometimes: a polymechanic (as Homer would name Odysseus for his all encompassing characteristics).
Being about half-way to your path in life, I feel good that there's so much more to learn and such great levels to reach. Thanks again for all the wisdom!
What you say makes most sense indeed.
3)
Indeed.
4)
How about using baking power with warm water? Any comments on this?
As for non-polar detergents, I looked at the labels, but they don't say.
5)
No wonder your writs are most elequent (loved the sentence about the asymptotic approach)! Where can one find your editorials?
I was right about the mad scientist comment!
Or more appropriately a panepisteme, or the term I prefer for myself sometimes: a polymechanic (as Homer would name Odysseus for his all encompassing characteristics).Being about half-way to your path in life, I feel good that there's so much more to learn and such great levels to reach. Thanks again for all the wisdom!
Baking soda is weakly alkaline in water. Weakly alkaline materials, and any foreign materials at all, are what you are trying to wash off. Mere drops of detergent in the wash water is all that you need, and in the rinse water, nothing. Look at, say, Wiki for info. about non-polar (non-ionic) detergents.
Mad, conceivably. Scientist by choice. I leave it to you to sort out the implications.
de :-x
Mad, conceivably. Scientist by choice. I leave it to you to sort out the implications.
de :-x
Hi equill,
0)
so you're saying that the alkaline nature of baking power could actually further accelerate the corrosion of copper (since copper, a transition metal, oxidizes more readily in the presence of alkaline materials). Did I understand this correctly?
Couple of more questions for you (if you're bored already, you don't have to answer them):
1) What about using 99% isopropyl alcohol? What's your diagnosis?
2) I've been trying to combat the similar corrosive effects of NiCd batteries. Any insights into that? Will warm water + non-polar detergent work best in that case as well?
Thanks again for all the great info!
0)
so you're saying that the alkaline nature of baking power could actually further accelerate the corrosion of copper (since copper, a transition metal, oxidizes more readily in the presence of alkaline materials). Did I understand this correctly?
Couple of more questions for you (if you're bored already, you don't have to answer them):
1) What about using 99% isopropyl alcohol? What's your diagnosis?
2) I've been trying to combat the similar corrosive effects of NiCd batteries. Any insights into that? Will warm water + non-polar detergent work best in that case as well?
Thanks again for all the great info!
da9000, I'm no chemist, but I can tell you that I've had good experiences with Dehydrated Ethanol. I reported about that in this post, and clicking on my link in that post will take you to the exact brand/bottle I use. I don't just use it for my Mac hobby's either. We use it at the office to clean circuit boards that we repair. Works great to clean up spilled cap fluid and solder resin -- and really, just about anything you could possibly spill on a circuit board. It dries fast too, so you can plug in your electronic device very quickly after cleaning.
While in no way decrying what JDW has settled on, I point out that anhydrous anything, by definition, has not water enough in it to dissolve polar materials. The inorganic (and organic—nothing to do with food faddism) non-polarized portions of capacitor electrolyte (the gelling agents) and the ionized molecules and ions (duh ...) dissolve in and are carried away best by the ionic solvent 'water'.
Truly anhydrous ethanol is so avid for water that it will imbibe water from the air, so making and keeping anhydrous ethanol anhydrous is an expensive pastime. The eutectic mixture of ethanol (what results from distilling a water/alcohol mixture) is about 92% ethanol, so you can see that solutions of ethanol in water (and water in ethanol) on either side of 92% ethanol are not stable, tending up or down towards the magic 92%.
Where anhydrous ethanol (and other liquids that can dissolve water) come into their own is as the last rinse, because they can remove remnant water from nooks and crannies (eg under surface mounted ICs and other components) more quickly than can simple evaporation of water. Ethanol, or a higher (longer-chain) aliphatic alcohol that does not deplete the logic-board's lacquer, then comes into its own. As I wrote in another post, commercial board-cleaning is usually done by sonicating boards in water containing suitable detergents, followed by rigorous rinsing. That's cheap and effective. If remnant water is dissolved off a board, as opposed to wiping or blowing it off, time can be saved. However, 98% ethanol is much cheaper for the purpose than is the fiendishly expensive 100% ethanol, or the not-much-cheaper 99.5% ethanol. Acetone is (relatively) cheap, and also infinitely miscible with water. However, it is dangerously flammable and probably can play merry Hell with board lacquers. In the end, one does what works, and swallows the cost, or seeks a less costly equivalent process.
The number of boards to be dealt with at any one time will influence the choice between quick and cheap.
de
Truly anhydrous ethanol is so avid for water that it will imbibe water from the air, so making and keeping anhydrous ethanol anhydrous is an expensive pastime. The eutectic mixture of ethanol (what results from distilling a water/alcohol mixture) is about 92% ethanol, so you can see that solutions of ethanol in water (and water in ethanol) on either side of 92% ethanol are not stable, tending up or down towards the magic 92%.
Where anhydrous ethanol (and other liquids that can dissolve water) come into their own is as the last rinse, because they can remove remnant water from nooks and crannies (eg under surface mounted ICs and other components) more quickly than can simple evaporation of water. Ethanol, or a higher (longer-chain) aliphatic alcohol that does not deplete the logic-board's lacquer, then comes into its own. As I wrote in another post, commercial board-cleaning is usually done by sonicating boards in water containing suitable detergents, followed by rigorous rinsing. That's cheap and effective. If remnant water is dissolved off a board, as opposed to wiping or blowing it off, time can be saved. However, 98% ethanol is much cheaper for the purpose than is the fiendishly expensive 100% ethanol, or the not-much-cheaper 99.5% ethanol. Acetone is (relatively) cheap, and also infinitely miscible with water. However, it is dangerously flammable and probably can play merry Hell with board lacquers. In the end, one does what works, and swallows the cost, or seeks a less costly equivalent process.
The number of boards to be dealt with at any one time will influence the choice between quick and cheap.
de
Just wanted to post this reminder...
It's Christmas!
:
Still haven't sourced all the right capacitors, but will report back when I have done the deed.