Editing Osborne 1 Troubleshooting Guide (section)

== Garbage screen / no boot ==

A non-boot with garbage characters is commonly a '''dynamic RAM (DRAM) failure'''. Piggy-back a known-good DRAM on each suspect chip to isolate the bad one, and replace it with anti-static precautions. Because the Osborne uses many socketed ICs and board-to-board ribbon cables that corrode, first '''reseat every socketed IC and every ribbon''' (especially the logic-to-CRT-board ribbon) and clean the pins with isopropyl alcohol.<ref name="osb">[https://www.classic-computers.org.nz/blog/2008-12-06-osborne-repair-1.htm Repairs to an old Osborne 1], Tezza's Classic Computers; [https://www.richardloxley.com/2018/04/03/osborne-restoration-part-3-servicing-the-psu-and-disk-drives/ Osborne Restoration: PSU and disk drives], Richard Loxley; and the [https://www.eevblog.com/forum/repair/osborne-1-repair/ EEVblog Osborne 1 repair thread]. Source for the PSU capacitor failures (RIFA smoke/bangs and the 4700/2200/1000 uF filter caps), the CRT/no-video checks, the disk-drive 12 V overload, the DRAM garbage-screen piggy-back test, and the socket/ribbon reseating.</ref>