At 2:22 PM -0500 11/22/02, Matthew B. Dwyer wrote: >Just in case you want follow-up info, the tech from Tekserve called back >today. He did two severe alcohol washes on it, and still no response (it >won't start at all) so he's replacing the logic board.
He should really do a water wash, as alcohol without water will not dissolve salts that may be the result of electrolytic corrosion. The board may be toast anyway. Electroplating can cause new conductive paths to form and lead to the complete failure of circuit traces. By the way, a lot of manufactures now use water soluble fluxes and water wash the boards after soldering. Years ago working on hybrid circuits for the MX missile we had a hybrid that failed at cold temperatures. It was necessary to troubleshoot it under a microscope where the connections between different integrated circuits could be probed with micro manipulators. This also had to be done when the part was cold. The device was placed under a microscope with a TV camera projecting the image to a video monitor, and power was applied. With the part powered up and operating, a device to produce cool air was lowered over the part and switched on. Unknown to us, condensation had formed in the cooler and was immediately expelled into the part when the blower started. Within seconds, a several thousand dollar radiation hardened military part was destroyed as the 1 mil IC bonding wires plated themselves onto their oppositely charged brothers, all in plain view on the TV monitor. Paul -- G-Books is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Check our web site for refurbished PowerBooks | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> G-Books list info: <http://lowendmac.com/lists/g-books.html> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/g-books%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
