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Cap Leakage
Hello all,
I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? Will washing the board with contact cleaner properly clean and or neutralize the effects?? I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. Thanks for any hints or tip on this matter. Have a good day. Les |
Cap Leakage
"ABLE1" wrote in message ... Hello all, I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? Will washing the board with contact cleaner properly clean and or neutralize the effects?? I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. Thanks for any hints or tip on this matter. Have a good day. Les Remove the capacitors and wash the board with detergent and warm water. Use a brush to scrub where there is corrosion. Dry in oven at 50-60 °C for several hours. |
Cap Leakage
ABLE1 wrote:
---------------- I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? ** It's usually ethylene glycol plus boric acid and loves to attack copper. Will washing the board with contact cleaner properly clean and or neutralize the effects?? ** Contact cleaner is undefined, can be damn near anything. I use a "Circuit Boaord Cleaner" that has a combination of hydrocarbon solvents and dries quickly. I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. ** Clean it up best you can and watch out if electrolyte has gone underneath. I have found a small fibreglass brush useful. http://au.element14.com/duratool/d02...4mm/dp/2102028 Really bad cases may need immersion in hot, detergent water to come good. ..... Phil |
Cap Leakage
On Saturday, 15 July 2017 01:51:00 UTC+1, tom wrote:
"ABLE1" wrote in message ... Hello all, I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? Will washing the board with contact cleaner properly clean and or neutralize the effects?? I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. Thanks for any hints or tip on this matter. Have a good day. Les Remove the capacitors and wash the board with detergent and warm water. Use a brush to scrub where there is corrosion. Dry in oven at 50-60 °C for several hours. Detergents also tend to be corrosive long term so clean it off well. NT |
Cap Leakage
On 7/14/2017 11:31 PM, Phil Allison wrote:
ABLE1 wrote: ---------------- I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? ** It's usually ethylene glycol plus boric acid and loves to attack copper. Will washing the board with contact cleaner properly clean and or neutralize the effects?? ** Contact cleaner is undefined, can be damn near anything. I use a "Circuit Boaord Cleaner" that has a combination of hydrocarbon solvents and dries quickly. I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. ** Clean it up best you can and watch out if electrolyte has gone underneath. I have found a small fibreglass brush useful. http://au.element14.com/duratool/d02...4mm/dp/2102028 Really bad cases may need immersion in hot, detergent water to come good. .... Phil Tom, NT, Phil, Thanks for all the input. I get the idea on cleaning. BTW as for "Contact Cleaner" I was referring to this one. https://www.zoro.com/crc-electronic-...00/i/G8578595/ Or similar, but may not be the most desired. Phil, as for the term "Circuit Board Cleaner" is there a specific brand that you use?? Presently searching for replacement caps. Once I acquire them I will dive into this project. Another question: Concerning the chip that has been effected. Can or could the electrolyte leach into the chips at the pins and cause problems with the chip in some way?? Or is the chip considered hermetically sealed is some fashion?? Thanks again!! Do appreciate the insight. Les |
Cap Leakage
On Saturday, 15 July 2017 13:09:57 UTC+1, ABLE1 wrote:
Tom, NT, Phil, Thanks for all the input. I get the idea on cleaning. BTW as for "Contact Cleaner" I was referring to this one. https://www.zoro.com/crc-electronic-...00/i/G8578595/ Or similar, but may not be the most desired. Phil, as for the term "Circuit Board Cleaner" is there a specific brand that you use?? Presently searching for replacement caps. Once I acquire them I will dive into this project. Another question: Concerning the chip that has been effected. Can or could the electrolyte leach into the chips at the pins and cause problems with the chip in some way?? Or is the chip considered hermetically sealed is some fashion?? Thanks again!! Do appreciate the insight. Les if they weren't sealed they wouldn't last long NT |
Cap Leakage
ABLE1 wrote:
Another question: Concerning the chip that has been effected. Can or could the electrolyte leach into the chips at the pins and cause problems with the chip in some way?? Or is the chip considered hermetically sealed is some fashion?? The typical commercial chips are epoxy molded around the lead frame and IC. So, the "seal" is just metal leads molded into the plastic body. Given enough time and humidity, it is possible for the leaked electrolyte or any other corrosive stuff to work its way along the lead and get to the bonding wires or the IC itself. Not real common, but it CAN happen. Military/aerospace chips are more hermetic, with kovar leads fused into a glass seal. But, enough corrosive stuff can get into those, too. it just takes longer. Jon |
Cap Leakage
On 7/15/2017 2:13 PM, Jon Elson wrote:
ABLE1 wrote: Another question: Concerning the chip that has been effected. Can or could the electrolyte leach into the chips at the pins and cause problems with the chip in some way?? Or is the chip considered hermetically sealed is some fashion?? The typical commercial chips are epoxy molded around the lead frame and IC. So, the "seal" is just metal leads molded into the plastic body. Given enough time and humidity, it is possible for the leaked electrolyte or any other corrosive stuff to work its way along the lead and get to the bonding wires or the IC itself. Not real common, but it CAN happen. Military/aerospace chips are more hermetic, with kovar leads fused into a glass seal. But, enough corrosive stuff can get into those, too. it just takes longer. Jon Thanks Jon, I understand. At this point I am going to replace the caps and see what happens. Hopefully that will be the complete fix. Les |
Cap Leakage
On Saturday, 15 July 2017 17:25:07 UTC+1, ABLE1 wrote:
On 7/15/2017 8:14 AM, tabbypurr wrote: On Saturday, 15 July 2017 13:09:57 UTC+1, ABLE1 wrote: Tom, NT, Phil, Thanks for all the input. I get the idea on cleaning. BTW as for "Contact Cleaner" I was referring to this one. https://www.zoro.com/crc-electronic-...00/i/G8578595/ Or similar, but may not be the most desired. Phil, as for the term "Circuit Board Cleaner" is there a specific brand that you use?? Presently searching for replacement caps. Once I acquire them I will dive into this project. Another question: Concerning the chip that has been effected. Can or could the electrolyte leach into the chips at the pins and cause problems with the chip in some way?? Or is the chip considered hermetically sealed is some fashion?? Thanks again!! Do appreciate the insight. Les if they weren't sealed they wouldn't last long NT Thanks NT, I got it. Was just wondering if the "seal" would be effected by the leaking electrolyte is some way. as said it's epoxy on metal so not likely. As a general question on these capacitors that leaked. Given the age (20+ years) would it be that they would have been effected by a power surge or just old age. old age and/or lack of power There are other radial caps on the board of the same size and value that do not show any leakage. I am asking in respect that given the condition should I just replace them all or only those that have leaked?? Given the bad state of some caps it's likely there are others that have gone high ESR and/or low capacity but not leaked. Most folk would replace the lot. You can get a £12 chinese component tester that'll tell you real capacity & ESR. See ebay, amazon, banggood etc. NT For me this is more of a fun experiment of sorts. I have been working with various electronics for 40++ years or so. Running my own business for the past 29 years. I have in the past but rarely have I gotten down to board level. As you can guess, if a component or board failed it was trash it and install a new. For critical devices it is not worth the time and liability to play around with board components. This project is quite different. I have already replaced the sound board with another and the repair project is completed. Just waiting to be paid. :-) I just want to see if my observation as to the condition of the caps was the real problem and can I fix it by doing a little board de-soldering, etc. Already on Digi-Key trying to source replacements. Again, thanks for the hints. Have a good rest of your weekend. Les |
Cap Leakage
ABLE1 wrote:
-------------------- Tom, NT, Phil, Thanks for all the input. I get the idea on cleaning. BTW as for "Contact Cleaner" I was referring to this one. https://www.zoro.com/crc-electronic-...00/i/G8578595/ Or similar, but may not be the most desired. Phil, as for the term "Circuit Board Cleaner" is there a specific brand that you use?? ** The brand I use is " RF " ( Richard Foot Pty Ltd ), available only here in Australia, AFAIK The CRC product you linked is likely similar - simple, fast evaporating hydrocarbon solvent. ..... Phil |
Cap Leakage
On 7/16/2017 7:51 AM, Phil Allison wrote:
ABLE1 wrote: -------------------- Tom, NT, Phil, Thanks for all the input. I get the idea on cleaning. BTW as for "Contact Cleaner" I was referring to this one. https://www.zoro.com/crc-electronic-...00/i/G8578595/ Or similar, but may not be the most desired. Phil, as for the term "Circuit Board Cleaner" is there a specific brand that you use?? ** The brand I use is " RF " ( Richard Foot Pty Ltd ), available only here in Australia, AFAIK The CRC product you linked is likely similar - simple, fast evaporating hydrocarbon solvent. .... Phil Thanks Phil, Most impressive.................... and they do Chocolate as well............. COOL!!! Les |
Cap Leakage
On Fri, 14 Jul 2017 20:51:30 -0400, "tom"
wrote: "ABLE1" wrote in message ... Hello all, I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? Will washing the board with contact cleaner properly clean and or neutralize the effects?? I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. Thanks for any hints or tip on this matter. Have a good day. Les Remove the capacitors and wash the board with detergent and warm water. Use a brush to scrub where there is corrosion. Dry in oven at 50-60 °C for several hours. I dont know if I'd place any electronics in an oven. Heat destroys components. Just sit it in the sun on a sunny day and it will dry. I have washed computer motherboards, including the power supplies, and hosed them off. (to remove all that dirt that builds up on that stuff), then left them out in the sun for a full day to dry, and they always work just fine. |
Cap Leakage
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Cap Leakage
On 7/16/2017 6:48 PM, Ralph Mowery wrote:
In article , says... I dont know if I'd place any electronics in an oven. Heat destroys components. Just sit it in the sun on a sunny day and it will dry. I have washed computer motherboards, including the power supplies, and hosed them off. (to remove all that dirt that builds up on that stuff), then left them out in the sun for a full day to dry, and they always work just fine. My oven will not regulate that low, so I put the wet equipment in a car that is out in the sun in the summer. Ah ha!! The discussion continues....................... COOL!!! |
Cap Leakage
Ralph Mowery wrote:
I dont know if I'd place any electronics in an oven. Heat destroys components. Just sit it in the sun on a sunny day and it will dry. I have washed computer motherboards, including the power supplies, and hosed them off. (to remove all that dirt that builds up on that stuff), then left them out in the sun for a full day to dry, and they always work just fine. My oven will not regulate that low, so I put the wet equipment in a car that is out in the sun in the summer. ** The trick is to bring the oven up to about 100C, then turn it off. Place the item inside and close the door, it will heat to about 75C and be dry as a bone in 15 minutes. Take it out and let it cool. 75C is not hazardous to electronic components. ..... Phil |
Cap Leakage
On 7/16/2017 8:28 PM, Phil Allison wrote:
Ralph Mowery wrote: I dont know if I'd place any electronics in an oven. Heat destroys components. Just sit it in the sun on a sunny day and it will dry. I have washed computer motherboards, including the power supplies, and hosed them off. (to remove all that dirt that builds up on that stuff), then left them out in the sun for a full day to dry, and they always work just fine. My oven will not regulate that low, so I put the wet equipment in a car that is out in the sun in the summer. ** The trick is to bring the oven up to about 100C, then turn it off. Place the item inside and close the door, it will heat to about 75C and be dry as a bone in 15 minutes. Take it out and let it cool. 75C is not hazardous to electronic components. .... Phil More CHOICES............... I love it!!! Thanks Phil, Les |
Cap Leakage
I used to have a different approach. This happened to Mitsubishi TVs alot because of electrolyte leaks. But I had a different problem sometimes and that was coolant leaks. Both substances act pretty much the same. At first, on the board they are pretty innocuous, but after a little time and voltage put across them they became corrosive and conductive.
But the caps themselves, I stopped changing them. Maybe they're doe leaking.. I took the board out for this. I started with acetone, and then alcohol. Brushed the hell out of it both times. Then rinsed it in the sink in hot water. This place had restaurant hot water. Remember to flood and brush both sides of the board. Then dry it with a hair dryer. Dry both sides, that gets the trapped water out of your SMDs. Repeat. I **** you not. And after that inspect and make sure you see no wet spots after the board is supposedly dry. That might be the remains of the chemical. That's how I used to do it. It worked. |
Cap Leakage
On Monday, July 17, 2017 at 9:37:10 PM UTC-4, wrote:
I used to have a different approach. This happened to Mitsubishi TVs alot because of electrolyte leaks. But I had a different problem sometimes and that was coolant leaks. Both substances act pretty much the same. At first, on the board they are pretty innocuous, but after a little time and voltage put across them they became corrosive and conductive. But the caps themselves, I stopped changing them. Maybe they're doe leaking. I took the board out for this. I started with acetone, and then alcohol. Brushed the hell out of it both times. Then rinsed it in the sink in hot water. This place had restaurant hot water. Remember to flood and brush both sides of the board. Then dry it with a hair dryer. Dry both sides, that gets the trapped water out of your SMDs. Repeat. I **** you not. And after that inspect and make sure you see no wet spots after the board is supposedly dry. That might be the remains of the chemical. That's how I used to do it. It worked. Years ago RCA sent a bulletin about the glycol leakage in the 195 series. They recommended an ammonia detergent. I used to buy tons of Parson's Sudsy Ammonia and mix it about 25-75 detergent to water. Remove anything that could trap liquid such as the flyback, smps transformer, cored inductors, etc. and give them a long hot bath in the brew. Rinse several times and put the board in the hot box for several hours. The boards looked like new and all problems caused by stray conductance disappeared. Not sure how the sudsy ammonia detergent works with electrolyte leakage but for the coolant leaks it was the bomb. |
Cap Leakage
On 7/17/2017 9:53 PM, John-Del wrote:
On Monday, July 17, 2017 at 9:37:10 PM UTC-4, wrote: I used to have a different approach. This happened to Mitsubishi TVs alot because of electrolyte leaks. But I had a different problem sometimes and that was coolant leaks. Both substances act pretty much the same. At first, on the board they are pretty innocuous, but after a little time and voltage put across them they became corrosive and conductive. But the caps themselves, I stopped changing them. Maybe they're doe leaking. I took the board out for this. I started with acetone, and then alcohol. Brushed the hell out of it both times. Then rinsed it in the sink in hot water. This place had restaurant hot water. Remember to flood and brush both sides of the board. Then dry it with a hair dryer. Dry both sides, that gets the trapped water out of your SMDs. Repeat. I **** you not. And after that inspect and make sure you see no wet spots after the board is supposedly dry. That might be the remains of the chemical. That's how I used to do it. It worked. Years ago RCA sent a bulletin about the glycol leakage in the 195 series. They recommended an ammonia detergent. I used to buy tons of Parson's Sudsy Ammonia and mix it about 25-75 detergent to water. Remove anything that could trap liquid such as the flyback, smps transformer, cored inductors, etc. and give them a long hot bath in the brew. Rinse several times and put the board in the hot box for several hours. The boards looked like new and all problems caused by stray conductance disappeared. Not sure how the sudsy ammonia detergent works with electrolyte leakage but for the coolant leaks it was the bomb. Ok, by my count we now have 6 totally different ways to clean and dry out a board. Scary too, I might choose the wrong one to do this one board?? Fear not guys................. I will choose wisely..................... OR DO THEM ALL just for fun, since I am confident that they all will be equally effective. But in what order.................. hmmmmmmmmmm Les |
Cap Leakage
On Tuesday, 18 July 2017 03:27:14 UTC+1, ABLE1 wrote:
Ok, by my count we now have 6 totally different ways to clean and dry out a board. Scary too, I might choose the wrong one to do this one board?? Fear not guys................. I will choose wisely..................... OR DO THEM ALL just for fun, since I am confident that they all will be equally effective. But in what order.................. hmmmmmmmmmm Les OK, here's number 7. Put it in a domestic dishwasher then warm room dry for a week. What does it matter? All you're doing is washing & drying. NT |
Cap Leakage (cont'd)
On 7/14/2017 8:45 PM, ABLE1 wrote:
Hello all, I have a sound amplifier board with what looks like some 25v 220mfd radial capacitors that appear to have leaked some of the electrolyte on to the board. The board is easily 20+ years old. One of the IC chips that is in the area appears to have some corrosion on the pins. If someone would be so kind to answer my questions they are as follows: Is the electrolyte some kind of acid base?? Will washing the board with contact cleaner properly clean and or neutralize the effects?? I plan on replacing the bad capacitors but want to be sure I am not missing something. I don't want to replace the chip unless it is damaged in some way. Thanks for any hints or tip on this matter. Have a good day. Les Ok, Update and another question. I removed all the leaking caps plus the others of the same type and size that had not shown signs of leakage just to be thorough. I then cleaned the board with some mild detergent, rinsed off and placed in my pre-heated oven at 220F and then turned off. Let set in the oven for about 2 hours while it cooled. Pulled the board out and it looks good. So far so good. It is now time to install the new caps. And then it hit me. This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. Is there some trick that needs to be applied somehow to get this soldered properly?? Again thanks for any thoughts or suggestions. Les |
Cap Leakage (cont'd)
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Cap Leakage (cont'd)
On 7/22/2017 4:30 PM, Ralph Mowery wrote:
In article , says... So far so good. It is now time to install the new caps. And then it hit me. This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. Is there some trick that needs to be applied somehow to get this soldered properly?? Hopefully the holes are what they call 'plated through' where there is a path through the hole to the other side that is conductive. Just use plenty of solder and heat and it should wick to the other side. Thanks Ralph, That was the key point I was missing. I metered each side of the board on one hole, and yes, I got continuity. Excellent!! Sooooooooo "Piece of cake". Thanks again. Les |
Cap Leakage (cont'd)
On Saturday, 22 July 2017 23:42:16 UTC+1, ABLE1 wrote:
On 7/22/2017 4:30 PM, Ralph Mowery wrote: In article , says... So far so good. It is now time to install the new caps. And then it hit me. This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. Is there some trick that needs to be applied somehow to get this soldered properly?? Hopefully the holes are what they call 'plated through' where there is a path through the hole to the other side that is conductive. Just use plenty of solder and heat and it should wick to the other side. Thanks Ralph, That was the key point I was missing. I metered each side of the board on one hole, and yes, I got continuity. Excellent!! Sooooooooo "Piece of cake". Thanks again. Les If it's a piece of cake you'll need to handle it quite carefully when soldering :) If electronics ever becomes edible that would solve the disposal issue. NT |
Cap Leakage (cont'd)
On 7/22/2017 8:54 PM, wrote:
On Saturday, 22 July 2017 23:42:16 UTC+1, ABLE1 wrote: On 7/22/2017 4:30 PM, Ralph Mowery wrote: In article , says... So far so good. It is now time to install the new caps. And then it hit me. This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. Is there some trick that needs to be applied somehow to get this soldered properly?? Hopefully the holes are what they call 'plated through' where there is a path through the hole to the other side that is conductive. Just use plenty of solder and heat and it should wick to the other side. Thanks Ralph, That was the key point I was missing. I metered each side of the board on one hole, and yes, I got continuity. Excellent!! Sooooooooo "Piece of cake". Thanks again. Les If it's a piece of cake you'll need to handle it quite carefully when soldering :) If electronics ever becomes edible that would solve the disposal issue. NT Funny........................ |
Cap Leakage (cont'd)
ABLE1 wrote:
------------------ Ok, Update and another question. I removed all the leaking caps plus the others of the same type and size that had not shown signs of leakage just to be thorough. ** FFS stop using the term "leakage" wrongly. In electronics, "leakage" refers to current passing through an imperfect insulator. What you have is caps *leaking electrolyte*. And then it hit me. This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. ** That makes no sense. You can see the component side and solder to it. The reverse side may be a problem to get at, but nearly all PCBs have plated through holes that you can solder from EITHER side. ...... Phil |
Cap Leakage (cont'd)
On 7/22/2017 9:33 PM, Phil Allison wrote:
ABLE1 wrote: ------------------ Ok, Update and another question. I removed all the leaking caps plus the others of the same type and size that had not shown signs of leakage just to be thorough. ** FFS stop using the term "leakage" wrongly. In electronics, "leakage" refers to current passing through an imperfect insulator. What you have is caps *leaking electrolyte*. And then it hit me. This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. ** That makes no sense. You can see the component side and solder to it. The reverse side may be a problem to get at, but nearly all PCBs have plated through holes that you can solder from EITHER side. ..... Phil Thanks Phil, Mental note made. Les |
Cap Leakage (cont'd)
On Saturday, July 22, 2017 at 3:32:11 PM UTC-4, ABLE1 wrote:
This is a double sided board. I am concerned that the component side of the board that is under the capacitor will not be soldered properly to the leads. Is there some trick that needs to be applied somehow to get this soldered properly?? You now know about the plated-through holes, but be aware that while they show continuity now, they may not after soldering. Some manufacturers do not feature sturdy plating in the holes (Samsung is one), and the added leaked electrolyte can aggravate it. Preheat the board, apply solder flux, use sufficient solder tip heat and carefully insert the capacitors through the holes. Don't force them like you might do on a single sided board. |
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