Optiplex 755 Amber lights

Hi fasner,

Welcome to the Community.

I got some information about the system Power LED indicators on the Optiplex 755. A blinking/flashing amber power button LED is a reliable indicator that the system is receiving power from a power source. This, in turn, tells us the source and power cord are likely to be functional. The blinking amber LED also tells us that the power supply-to-system board connection is good, along with the connections among the system board, I/O panel, and control panel.

Based on the information given by you, this could be an issue with audio ribbon cable that is connected between the front fan assembly and front USB assembly. So if the system is booting fine without the audio ribbon cable, the front fan or the front USB assembly should be rendered useless, hence disconnect the audio cable and boot the system to windows and check if the front fan, audio and USB ports are working. This will help us isolate the issue further.

This system also has diagnostic LEDs which are located on the front of the chassis between or below the headphone connector and the USB connectors, depending on the chassis. The diagnostic LEDs are located on the back of the system on the ultra small form factor (USFF) chassis. These diagnostic LEDs are only active and visible during the POST process.

The diagnostic LEDs come up with 1,2,3,4 pattern. Hence please make a note of the LEDs that turn On and stay during the POST process.

Kindly reply with the results.

You may have the same problem with this one. Check it out:

en.community.dell.com/.../19763708.aspx

I appreciate any feedback, Thank you. I have tried several front fan ribbon cables/fan assemblies with the same result. I have the Optiplex 755 Small Form Factor unit. Motherboard PN PU052, Processor E2140. I also changed the front panel I/O assembly as well (three different ones)

I did a lot of reasearch on this as I see I am not alone with this. It seems there are many reasons for this issue. I ordered another Power Supply as this is the only piece of equipment I did not change. I have 3 motherboards all doing the same exact thing. I am pretty sure its not the mobo's. I assume the audio circuit is asking for +5 volts from the power source. Could the power supply be failing just on that?  It seems to be suppling power to the other connectors ok. I will try and get this to boot to Windows as you asked and see if it is a BIOS issue. If I can do a BIOS update maybe that will work. I know at this point I am just desperate as I am afraid to buy another MOBO and have the same thing. Thank you again.

Thank you for the response. I tried the power Switch at the Power Supply it is at 110 volts. I tried the Motherboard 4 pin power connector, I tried the 24 pin power connector, doesn't seem to be the culprit. Just don't know.-frustrating.

After reviewing-I realized the the ribbon cable coming from the USB I/O assembly was plugging into the small PCB located in the CPU fan assembly. It has nothing to do with the audio. The really weird part is if I plug in the ribbon cable in such a way that the only thing working is the amber led lights, the system will boot to POST. As soon as I plug the ribbon cable into the PCB at the fan assembly in all the way-the system board will not boot, just get the flashing lights again. I don't have the readout as to why this would be. I purchased another PCB and that did it. Maybe different REV levels--don't know for sure--any thoughts on this would be greatly appreciated since I now have 5 Fan assembly PCB's that don't work with this board.