03-15-2013, 07:49 PM
Welcome!! Others may have some experience with this model and additional advice but you may be able to get schematics at Steve Johnson's site: http://www.antiqueradioschematics.org/philco.htm . It has M-1688 listed. Much of the discussion and information on this phorum is on radios older than yours (which based on the listing at http://www.radiomuseum.org/r/philco_m_1688m168.html was built around 1964) but that doesn't mean you won't get help if you ask.
