B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 194.8; Flight Crew Type 633.12
Confusion; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Overcame Equipment Problem
Aircraft
Departing LAX from [Runway] 25R on the ORCKA 3 RNAV SID.  On initial climb and somewhere around the DOCKR intersection; my flight director bar disappeared.  Because of this; I cannot say with complete confidence that we made the required turn to 236 degrees at DOCKR as required per the RNAV SID.  We did make the left turn as soon as possible without LNAV or flight director and used the heading bug as a reference.  I do not know what caused LNAV/VNAV to disengage. We did encounter changes in pitch; roll and airspeed about that moment commensurate with a minor wake turbulence encounter.  However; I do not believe this was related to the loss of LNAV/VNAV but did contribute to the overall confusion of the situation.  We were able to re-engage LNAV/VNAV and also autopilot and the departure continued uneventfully.
B737NG First Officer reported a track deviation occurred departing LAX after the flight director bar disappeared.