Re: Optiplex 755 only turns on through power supply button, no video output.
It does sound like there is a problem with the power supply but I've got some steps that will help you determine exactly what is happening. Some of these steps require opening the system so please remove the power cord from the back of the system before doing these steps. If you can answer the following, it would be a great help:
1) Switch the system on. Can you tell me the colour of the power button and also whether the power button is flashing or not? Please also tell me if you notice any diagnostics LEDs staying lit - these are labelled 1,2,3 and 4 and are near the front headphone sockets.
2) Does the LED on the power supply stay lit if you hold the power supply test button in/
3) Please remove all peripherals at the back of the system and switch the system on. Does this affect the power button LED or diagnostic LEDs?
4) Have you added any components to the system e.g. video cards, sound cards etc...
5) Please open the system and remove the following components:
a) Power and data cables from hard drives and optical drives
b) Any PCI/PCI-Express expansion cards
c) All memory from the system
d) The system fan
6) With the above removed, please reconnect the power cord to the back of the system and switch the system on. Please make a note of what happens with the power button LED and the diagnostic LEDs.
7) If there are no changes to the power button LED or diagnostic LEDs, please remove the power cord from the back of the system and remove the following components:
a) I/O panel cable
b) CMOS battery
8) With the I/O panel cable and CMOS battery removed, please connect the power cord to the back of the system. The system should automatically try to switch on. Do you hear any beeps from the system? If so, can you tell us exactly what you hear?
If you need any assistance removing components, this manual will show you how to do so: <ADMIN NOTE: Broken link has been removed / replaced from this post by Dell>
Please let us know how you get on with the above steps.
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