First post, by Kahenraz
While examining my Roland Sound Canvas SC-55mkII while investigating a broken MIDI socket I spotted what appeared to be some minor corrosion around the DC filter capacitor. I might have ignored it completely had I not seen an episode of Adrian's Digital Basement where he discovered an adhesive that turned corrosive and destroyed part of a PCB he was repairing.
Unlike other adhesives I've seen used to secure large capacitors which remain somewhat pliable, this one had hardened and begun to crack. I don't know if this is a result of the chemical composition or its exposure to high temperatures near the VRM circuitry but it can be identified as an opaque dark brown that is consistent in color throughout.
After removing the capacitor and scraping away the adhesive, I found that the area underneath had become discolored with bits of corrosion just barely visible. While the board still looked serviceable on its face, whatever reaction had taken place had penetrated the lamented surface and begun to dissolve the copper ground plane underneath as well as some nearby traces.