Problem using iMacs as an external display

hi,

trying use imacs available in school's library external display macbook pro. first time worked, have no success since then. wondering if can me troubleshoot.

macbook pro mid 2013, , imac mid 2011. both have thunderbolt ports. bought thunderbolt cables connect them. first time tried, worked right away. didn't had press cmd + f2 suggested in apple website.

since not working anymore. when connect thunderbolt cable in either of ports, system report on thunderbolt port of macbook reads "no device connected"

have tried following troubleshoot problem:

- tried many different imacs in same library
- tried different cables imacs
- tested , ensured 1 of cables defective have @ least 1 working cable. ensured trying cable 27 thunderbolt display
- have reset smc , nvram of macbook pro
- contacted support of library mentioned imacs have no such things thunderbolt port. wrong because worked through thunderbolt cable first time

wondering if there else can try solve problem decisively. how can determine origin of problem?

if being blocked system admin after first try, possible check reading system report?

assuming not need reset smc , nvram of imacs because not working in either of them , seems unlikely of them require resets.

try next?

 

if command-f2 doesn't work
if imac doesn't switch target display mode when press command-f2, check these things:

• make sure imac you're trying use display supports target display mode.
• make sure you're pressing command-f2 on keyboard that's connected imac want use display.
• in keyboard system preferences, if checkbox enabled use f1, f2, etc. keys standard functions keys, key combination changes command-fn-f2.
• make sure mini displayport or thunderbolt cable connected both computers.
• if you're logged in on imac want use display, try logging out return login window. press command-f2 again.
• some older apple keyboards , third-party keyboards might not allow command-f2 toggle display modes. if happens, use keyboard came imac toggle target display mode on , off.
• if imac started in windows, won't enter target display mode. target display mode isn't supported in boot camp.

give try , maybe question protection might on imac stop outside connections....

 

Forums Macs Desktops iMac

• iPhone
• Mac OS & System Software
• iPad
• Apple Watch
• Notebooks
• iTunes
• Apple ID
• iCloud
• Desktop Computers
• Apple Music
• Professional Applications
• iPod
• iWork
• Apple TV
• iLife
• Wireless