[time-nuts] Completely OT: Removing electrolytics of leakingcapacitors from a pcb
paulswedb at gmail.com
Wed Jan 19 14:52:05 UTC 2011
Do agree with the vinegar.
Essentially its a acid and opposite of the stuff so it neutralizes the
actions converting to some sort of salt that needs to be removed.
I ran into this on a hp 3586 but it was a nicad battery. These commonly leak
due to age and a really poor charging circuit. A resistor.
Unfortunately if the stuff has eaten into the board you have to cut/dig it
out until the path to other traces are high Z again. I understand thats hard
to determine but if you don't the system slowly destroys itself over time.
You will always be coming back to the same area.
Worst case and this has happened to me. Clean the area, cut and isolate the
traces and then solder in new wires to replace the stranded traces. Ugly but
it is the last resort.
You can run into this because the stuff we get typically used may have been
in a damaged state for years. So you are stuck.
On Wed, Jan 19, 2011 at 9:36 AM, Alan Melia <alan.melia at btinternet.com>wrote:
> Hi Ulrich, yes its nasty. As far as I am aware the "liquid" electrolyte is
> an alakali, sodium or potasium hydroxide. This retains the insulator
> (aluminium oxide) on the plates by electrolytic action. When spewed on to
> the PCB it is conducting and starts and electrolytic reaction that will eat
> away the tracks. This will happen faster with power applied but will occur
> if the circuit is unpowered. I have removed some of this, and the efflent
> from leaky NiCd bats (Potassium hydroxide) with a swab soaked in vinager,
> and then flushed the area clean and dried it in alcohol. It may depend on
> how old and caked the deposit is but the sodium acetate (??) should be
> soluble in water, where hydroxides and carbonates are not. The danger is
> getting liquid trapped under components, alcohol is not too much of a
> problem but vinegar left could be as corrorosive eventually as the
> electrolyte guge if not fully removed.
> I have never needed to try this on a tracked PCB but I dont see why it
> shouldn't do the job. Others will not doubt comment :-))
> Alan G3NYK
> ----- Original Message -----
> From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
> To: "Time nuts" <time-nuts at febo.com>
> Sent: Wednesday, January 19, 2011 2:02 PM
> Subject: [time-nuts] Completely OT: Removing electrolytics of
> leakingcapacitors from a pcb
> > Gentlemen,
> > I know this is completely out of topic but I know there are some
> > material experts among you. So please allow me to put the following
> > forward:
> > Is there any good suggestion available on how to remove electrolytic
> > resulting from leaking electrolytic capacitors from a pcb? It is not a
> > question of good looking, the coating seems to have a real "electrical
> > conducting" property which is absolutely bad on higher-impedance
> > as to be found on a Tektronix TDS45A scope mainboard, where the problem
> > encountered. The findings so far are that the classical method with
> > isopropanol and a brush won't work. And the internet won't give precise
> > answers for that problem.
> > Any suggestion is highly appreciated!
> > Best regards
> > Ulrich Bangert
> > www.ulrich-bangert.de
> > Ortholzer Weg 1
> > 27243 Gross Ippener
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