What was found
DURING CLIMB ABOVE 18,000 FT, OVERHEAD PANEL WENT COMPLETELY DARK. NO INDICATION LIGHTS OF ANY KIND EXCEPT ENGINE IGNITION WERE ILLUMINATED. ON PREFLIGHT THE NR 4 & 5 DISPLAY UNITS BLANKED OUT FOR ABOUT 30 SECONDS & THE HYD PANEL SAID SELECT MANUAL. THOSE ISSUES WENT AWAY AND THE PREFLIGHT PROCEEDED NORMALLY. NOTED O/H PANEL LIGHTING NORMAL ON ARRIVAL TO THE ACFT. MM 33-11-03-2. REMOVED AND REPLACED THE DIMMER, CYCLED POWER BACK AND FORTH BETWEEN GROUND POWER AND APU POWER WITH ALL INDIATIONS NORMAL, RHEOSTAT DIMMED AND BRIGHTENED ALL BACK LIGHTING ON OVERHEAD PANEL, OPS TEST NORMAL IAW 33-11-03-2. ACFT OK TO CONTINUE.