[Premium-Rx] Eddystone 1650-3 , with text

[richardreich at aol.com]

Dan its absolutely right regarding acid alky effects. 
Standard plastic packages have a propensity for absorbing fluids anyway - particularly at the lead joints - leading to eventual long-term failure.
 This is one of the reasons why high performance semiconductors (eg military) are packaged in ceramic as a preference. I suspect that alky has already worked its way in.
Change all the chips for new once the PCB is clean.

R

Sent from my BlackBerry® smartphone on O2

-----Original Message-----
From: Dan Rae <danrae at verizon.net>
Sender: premium-rx-bounces at mailman.qth.net
Date: Sat, 23 Mar 2013 11:54:43 
To: <premium-rx at mailman.qth.net>
Subject: Re: [Premium-Rx] Eddystone 1650-3 , with text

On 3/23/2013 9:20 AM, Peter Ratuschni wrote:
> The trouble was first that it first showed nothing usefull and did not react to the power button. The owner then replaced the leaked battery. The acid had derogated the cpu-board,
Peter if you are talking about a Nicad battery the leakage is an alkali 
not acid, but nasty stuff all the same.  I have fixed a lot of Racal cpu 
boards damaged this way and the first step is to actually wash with a 
dilute acid like vinegar and then rinse many times with isopropyl 
alcohol.   I don't know your particular board, but with the Racals that 
stuff has a habit of wicking under the PC resist layer and attacking 
VIAs and other copper.  It can destroy IC sockets, 34 way IDC 
connectors  and has a sneaky habit of travelling up Transistor leads to 
the point where they enter the epoxy body and eating right through 
them.  A green / blue coloured deposit will be a clue as to where to 
look first.

Then it is 'just' a question of checking continuity.   And the 
replacement battery can be an NiMH type, which I have yet to see leak.

Good luck!

Dan


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