Cap Leakage

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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



Re: Cap Leakage

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Remove the capacitors and wash the board with detergent and warm water. Use  
a brush to scrub where there is corrosion.







Re: Cap Leakage
On Saturday, 15 July 2017 01:51:00 UTC+1, tom  wrote:
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ial  
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on  
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se  
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Detergents also tend to be corrosive long term so clean it off well.


NT

Re: Cap Leakage
wrote:

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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.



Re: Cap Leakage
snipped-for-privacy@tubes.com says...
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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.



Re: Cap Leakage
On 7/16/2017 6:48 PM, Ralph Mowery wrote:
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Ah ha!!  The discussion continues.......................  COOL!!!



Re: Cap Leakage
Ralph Mowery wrote:


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** 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  

Re: Cap Leakage
On 7/16/2017 8:28 PM, Phil Allison wrote:
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More CHOICES............... I love it!!!

Thanks Phil,

Les


Re: Cap Leakage
I used to have a different approach. This happened to Mitsubishi TVs alot b
ecause of electrolyte leaks. But I had a different problem sometimes and th
at was coolant leaks. Both substances act pretty much the same. At first, o
n 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. Br
ushed the hell out of it both times. Then rinsed it in the sink in hot wate
r. This place had restaurant hot water. Remember to flood and brush both si
des of the board. Then dry it with a hair dryer. Dry both sides, that gets  
the trapped water out of your SMDs.  

Repeat. I shit 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.

Re: Cap Leakage
On Monday, July 17, 2017 at 9:37:10 PM UTC-4, snipped-for-privacy@gmail.com wrote:
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 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 voltag
e put across them they became corrosive and conductive.  
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ng.  
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Brushed the hell out of it both times. Then rinsed it in the sink in hot wa
ter. 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 get
s the trapped water out of your SMDs.  
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et spots after the board is supposedly dry. That might be the remains of th
e chemical.  
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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 Suds
y Ammonia and mix it about 25-75 detergent to water.  Remove anything that  
could trap liquid such as the flyback, smps transformer, cored inductors, e
tc. 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 an
d all problems caused by stray conductance disappeared.  Not sure how the s
udsy ammonia detergent works with electrolyte leakage but for the coolant l
eaks it was the bomb.


Re: Cap Leakage
On 7/17/2017 9:53 PM, John-Del wrote:
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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





Re: Cap Leakage
On Tuesday, 18 July 2017 03:27:14 UTC+1, ABLE1  wrote:

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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

Re: Cap Leakage
 ABLE1 wrote:

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 ** It's usually ethylene glycol plus boric acid and loves to attack copper.  


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** 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.  


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** 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/d02266/pen-pcb-cleaning-fibreglass-4mm/dp/2102028

Really bad cases may need immersion in hot, detergent water to come good.  



....  Phil  


Re: Cap Leakage
On 7/14/2017 11:31 PM, Phil Allison wrote:
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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-component-cleaner-13-oz-02200/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

Re: Cap Leakage
On Saturday, 15 July 2017 13:09:57 UTC+1, ABLE1  wrote:

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if they weren't sealed they wouldn't last long


NT

Re: Cap Leakage
On 7/15/2017 8:14 AM, snipped-for-privacy@gmail.com wrote:
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Thanks NT,

I got it.  Was just wondering if the "seal" would be
effected by the leaking electrolyte is some way.

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.

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??

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

Re: Cap Leakage
On Saturday, 15 July 2017 17:25:07 UTC+1, ABLE1  wrote:
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578595/
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d

as said it's epoxy on metal so not likely.

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old age and/or lack of power

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Given the bad state of some caps it's likely there are others that have gon
e high ESR and/or low capacity but not leaked. Most folk would replace the  

capacity & ESR. See ebay, amazon, banggood etc.


NT

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Re: Cap Leakage
ABLE1 wrote:


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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

Re: Cap Leakage
On 7/15/2017 2:13 PM, Jon Elson wrote:
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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



Re: Cap Leakage
 ABLE1 wrote:

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 ** 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  

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