Lukas Guy, try what apple suggest for the trouble shooting first:"
Dead Unit / No Power
Unlikely cause: LCD panel, blower, subwoofer, speakers, camera, microphone
Quick Check
Symptoms
Dead Unit / No Power
• No power
• No image
• No fan spin
• Non-operational
Quick Check
1. Verify power source.
2. Verify USB/display/power connectors are fully
seated.
3. Verify display is used with supported system.
4. Use with known-good system.
If used as second display, check display
preferences to see if display is recognized.
5. Check brightness setting.
Deep Dive
1. Verify display’s USB hub and built-in camera are listed in the
System Profiler’s USB device tree.
Yes Power supply OK. Go to Blank/No Video symptom code flow.
No Go to step 2.
2. Unplug and replug the Mini DisplayPort connector into a supported system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes Logic board OK. Go to Blank/No Video symptom code flow.
No Go to step 3.
3. Remove LCD panel and disconnect LCD function interface cable. Verify voltage on logic board between test point TP11 (24.5VDC) and chassis ground (GND) is 23.3–25.7 VDC.
Yes 24.5VDC from power supply
OK. Go to step 4.
No No power or incorrect power at logic board.
Go to step 6.
4. Verify voltage on logic board between test point TP61 (3.3VDC) and chassis ground
(GND) is 3.1–3.5 VDC.
Yes 3.3VDC power on logic board OK. Go to step 5.
No No power at logic board. Go to step 9.
5. Verify voltage on logic board between test point TP13 (12VDC) and chassis ground
(GND) is 11.4–12.6 VDC.
Yes All DC voltages present on logic board; power OK. Go to Blank/No Video symptom
code flow, Step 3.
No No power at logic board.
Go to step 9.
6. Verify all connections between power supply, all-in-one cable, and logic board are secure. See Functional Overview.
Yes If connections are secure and display still does not function correctly, go to step 8.
No Reseat connectors and retest.
7. Disconnect power supply cable from logic board. Verify cable voltage at connector between
Pin 1 and chassis ground (GND) is 14.3–15.8 VDC.
Yes Go to step 8.
No No power or incorrect power to logic board.
Replace power supply.
8. Disconnect all connectors from the logic board EXCEPT the power supply cable.
Verify voltage on logic board between test point TP11 (24.5VDC) and chassis ground
(GND) is 23.3-25.7 VDC.
Yes Power supply OK. Suspect possible short, damaged connector, or faulty sensor/
fan/speaker. Reconnect connectors one at a time and retest for 24.5VDC at TP11.
Replace affected part that causes the 24.5VDC voltage to disappear.
No Replace power supply.
9. Disconnect all connectors from the logic board EXCEPT the power supply cable.
Verify voltages on logic board between test points TP61 (3.3VDC) and chassis ground (GND) is 3.1–3.5 VDC, and between TP13 (12VDC) and chassis ground (GND) is 11.4–12.6 VDC.
Yes Power supply OK. Suspect possible short, damaged connector, or faulty sensor/ fan/speaker. Reconnect connectors one at a time and retest for 3.3VDC at TP61 and 12VDC at TP13. Replace affected part that causes the 3.3VDC or 12VDC voltages to disappear.
No Replace logic board.
Let us know what you find. Hope this helps, good luck.
1 Opmerking
Lukas Guy, have you taking it apart yet? Checked the power supply for bad caps etc? I am not quite convinced that it is the LCD panel, since that should not impede all the other functions.
door oldturkey03