|Heat staked keyboards with sticky, bouncy or corrosion present keyboard PCAs|
Message #1 Posted by Geoff Quickfall on 10 Aug 2009, 9:30 p.m.
Thought I would post the following which is found embedded in a previous topic soon to be lost. I hope this helps the community at large. It was in response to the question:
What did you mean by "washing" the PCA's?
When I restore a calculator with a heat staked keyboard, especially one with corrosion due to either battery leakage or out gassing I use a wash on the PCA.
a: To remove any vertigris (green or white precipitate) I rinse
(wash) the PCA with a mild vinegar solution followed by a
distilled water rinse and then 95% anhydrous ethanol (in Canada
thats known generically as 95% rubbing alcohol although I have
seen it labelled isopropyl alcohol).
b: For stickey keys, a very dilute soap and water wash with water
rinse and anhydrous ethanol rinse
c: If there is no corrosion or stickey keys I use the water wash
followed by the anhydrous ethanol rinse.
Of course, sticky keys with corrosion would get both treatment a and b.
Heat staked keyboards with bouncy keys or even intermittant keys respond well to this and I have resurrected bad keyboards on:
Of course the Classics and Spice keyboards can be diassembled and cleaned mechanically.
Fill the glass to a level below the LCD or LED if they are soldered in place. In the case of the woodstocks the LED module can be removed.
Edited: 11 Aug 2009, 4:30 a.m.