Re: Aw: JU570-2 caps and fix

From: Gerrit Heitsch <>
Date: Thu, 24 Sep 2015 16:54:53 +0200
Message-ID: <>
On 09/23/2015 11:49 PM, HÁRSFALVI Levente wrote:
> Hi All!,
> Having fixed 3 JU570-2 drives and still having 3 faulty ones left ;-),
> well... I might say I'm getting worried about a little detail.
> Let me explain... The PCB of the JU570-2 appears to be some FR2 based,
> cheap, single sided board. FR2 is AFAIK a porous material. The
> observable nature of the corrosion (which always seem to happen without
> any noticeable marks of leak on the solder side) seems to suggest that
> corrosion is done by acid adsorbed by the PCB (which eventually seeps
> through to the solder side of the board).
> (This is IMHO very different from the Amiga, and other equipment
> affected by capacitor leak... FR4 and similar glass fibre + epoxy based
> PCBs are generally not porous, they don't absorb liquids. That means
> that a good cleaning + oxide removal as needed + applying some acryllic
> paint or solder resistant lac generally prevents further harms to the
> PCB traces.)
> Any ideas and/or experiences? I've made an attempt to neutralize the
> acid remnants using sodium carbonate solution, but I'm getting less
> convinced that that's going to work in the medium term. And I'd hate to
> find out later that the drives gave up despite the work invested (and
> anyway...).

The first question to answer would be whether the electrolyte is an acid 
or a base. NiCd batteries for example don't leak an acid but a base 
(potassium hydroxide), so you need to neutralize it with an acid 
(vinegar comes to mind) when fixing for example an Amiga where the clock 
battery leaked.

Can one still buy test strips at the local pharmacy?


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Received on 2015-09-24 15:00:07

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