TM  11-5820-890-20-2 2-112 2.2. TROUBLESHOOTING FLOWCHARTS. Continued Chart 31 RT-B WILL NOT KEY FROM COMMANDER'S C 2298. MONITOR SWITCH SET TO C. (Sheet 2 of 2) V U T S R P N M L K J H F E D C B A MB J4, AM 1780 J503, J504 NO YES OPEN ? REPLACE MB. CHECK CONTINUITY AT VAA P1, PIN S TO J4, PIN C. NO YES OPEN ? REPLACE AM 1780. 1.   REMOVE CX 13300 FROM J503 OF AM 1780. 2.   CHECK CONTINUITY AT AM 1780 J503, PIN S TO J504, PIN F. NO YES OPEN ? REPLACE VAA. 1.   REMOVE VAA FROM MB. 2.   REMOVE CX 13300 FROM MB  J4. 3.   CHECK CONTINUITY AT MB J4, PIN S TO J5, PIN S. REPLACE CX 13300. J H P K S R N M L F E D B A C V U T MB J5 A D B C E F K S U T L H M V R P VAA P1 N J 1 SH 2 F E D C B A VAA J4