|Re: ":Drop testing" a TI-59|
Message #19 Posted by Vieira, Luiz C. (Brazil) on 6 Jan 2010, 1:45 p.m.,
in response to message #18 by Bart (UK)
The one you see in the picture is a TI58C (is yours a 'C', too?), and it also had some blue powder (seems to be copper oxide, is that so?). Now, please, have a look at the picture pointed by this link.
TI58C and TI59 corrosion compare(Big pic: about 1.9 Mbytes)
The TI59 board (right side) has a lot of oxidation, and the TI58C board (left) seems cleaner, right? They had both about the same oxidation level before I left the TI58C resting for about 20 hours in a solution of 30 to 40% alcohol vinegar with hot water (could touch it without feeling pain...). You can see some of the copper oxide in the TI58C´s PC100A contacts, and also notice the missing copper (parts totally destroyed).
Battery leakage is mainly basic (PH), and the alcohol vinegar is acid, so they react with each other and the remains of the reaction (a salt, right?) is easily removed with a paint brush, current water and neutral detergent. As you can see, I removed the LED display, power supply and some components (transistors, elect. caps, "SSS" module contacts, etc.) prior to clean it up.
I have been doing this for some time (woodstocks and these TI's, mostly) and have successfully removed copper oxide from them. In one particular case, a TI59 board with extensive oxidation damage, had the remains of many copper tracks being dissolved or popped out of the mainboard.
The hot water accelerates the reaction, but after some time its temperature raises down and the reaction decelerates as well. Anyway, I always keep my eyes over the board during the process and never let it stays for more than 20-22 hours.
Hope this helps.