Question about Dell Optiplex 755 Desktop Desktop Computer

1 Answer

System unit led is yellow and start good condiotion but no signal

Posted by Anonymous on

  • joecoolvette
    joecoolvette May 11, 2010

    Suggest the computer - Doesn't start in good condition. It just seems that way. No Signal on the monitor, means the computer is Not sending a video signal. This is because the computer isn't working. Could be due to something as simple as one, or more, Ram Memory modules are loose, and not fully seated in the ram slot. I'm willing to bet it's a bad power supply. Has a weak voltage power rail. Enough power to light light's, maybe spin fans, but not enough to turn the Processor on. 1) ALL the lights use less than 1 Watt of power. 2) EACH fan uses 2 to 3 Watts. 3) A typical Processor uses 51 to 125 Watts. Depends on what processor it is. On the harddrive is a boot sector. The processor must be running in order to find, and implement the boot sector. Otherwise the harddrive just sits there, and spins. Makes it sound as though the harddrive is operating, but it's not. (Inside the harddrive are Platters. They resemble CD disks. These are what is spinning inside the harddrive. More info on this,http://computer.howstuffworks.com/hard-d... ) This is Dell Support, and the User Manual page for the Optiplex 755 series. Click on which style of Optiplex 755 you have,(http://support.dell.com/support/edocs/sy... ) I chose Desktop for an example. In the left column of the list click on - Troubleshooting. Now click on - Power Lights.

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  • 79 Answers

HI this could be due to static

do the following

1) unplud all the cables from back of the Tower including the power cables

2) press and hold the power button for 30 seconds

3) put back the cables and check.

Posted on May 11, 2010

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Posted on Jan 02, 2017

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1 Answer

Bluetooth peripheral device driver


Sai Ch Krishna,

Depending on the system. The bluetooth would have to have been purchased at point of sale. The wireless and the bluetooth are turned on by a wireless switch on the side of the computer. If needed you can reinstall the drivers. Also, make sure bluetooth is turned on in the bios. Below is more information.
Wireless Switch

Wireless Technology The Latitude D630, D631, and D630c system ships with a wireless feature called the wireless switch. It is located on the left side of the system next to the IEEE 1394 connector. When used in combination with the Dell 38482; Quickset utilities, this switch enables or disables the wireless LAN, wireless WAN, and Bluetooth cards in the system or searches for all wireless networks in range.
To scan for a Wi-Fi wireless LAN, slide and hold the switch in the momentary position for a few seconds. The Wi-Fi Catcher network locator works whether the computer is turned on or off, in Hibernate mode, or in Standby mode, as long as the switch is configured through QuickSet or the BIOS to control Wi-Fi network connections.
Because the Wi-Fi Catcher network locator is disabled and not configured for use when the computer is shipped, it must be enabled and configured through the Dell QuickSet utilities to control Wi-Fi network connections.

Wireless Switch LED Settings
The LED on the wireless switch works even if the system is off. A user can activate the switch and have it scan for networks without going through a complete boot process. The switch can be set to detect for only certain wireless signals, such as WLAN only, WWAN only, Bluetooth only, or any combination of these. This is set in the BIOS under the Wireless section.
The LED indicates the presence of a network as follows:
  • Flashing green - The system is searching for a signal.
  • Green - The system has detected a wireless signal and has good strength.
  • Yellow - The system has detected a wireless signal, but it is moderate to weak in strength.
  • Red - The system failed to detect a wireless signal, or the wireless signal is extremely weak.
Thank You,
Dell-Jesse L
Dell Social Media and Communities

Aug 27, 2013 | Dell Computers & Internet

1 Answer

Power LED is On but system doesnot start ?


hello, I have a solution for u i think it may help for u.
your problem is:

When u press the start button... the power LED comes on but there is no POST beep or BIOS screen or boot up. The SMPS fan and Processor fans also dont come on at all. there is a small LED next to the SMPS plug on the motherboard that does light up when the system is connected to a power source.
Part of the system configuration is the kind of PSU you have in your system.
SOLUTION IS
So, what kind of PSU?

Try to borrow a known good PSU. Or better yet, see if you can test your PSU in another working system. If you cannot do that, try to borrow a DMM to measure the voltages. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead.

Jul 01, 2010 | ASUS P4P800 SE (890552603657) Motherboard

1 Answer

System unit led is yellow and start good condiotion but no signal


The light on the LCD screen stays yellow?

I would start with puling out the ram chips and see if it works,

If you get some beeps and video works with ram chips out, then its a bad ram chip.

If thats not it.. unplug all cards cd/dvd rom and harddrive to test motherboard and CPU chip. see if you can get video to work with everthing but cpu and power suppy unpuged

Apr 28, 2010 | Dell Optiplex 755 Desktop Desktop Computer...

2 Answers

I replaced the video card and it still will not boot up.


IF A&B are yellow and C&D are green it indicates a memory error.

If A&B are yellow and C&D are off then it indicates that the computer is in sleep or reduced power mode.

What was your symptoms before you replaced the video card? Sometimes if the power supply is weak or bad or you have a bad motherboard then you get no video output. Check your cpacitors on your mobo for leaking or swelling. Let us know what you find out.

Apr 30, 2009 | Computers & Internet

1 Answer

Dell Power Up Problem


No Power, No POST, No Video
1. STEP: Ensure Correct Power Button Is Used and Is Not Sticking or Broken. If the power button remains depressed during the power-on attempt, the computer immediately powers off, mimicking a "no power" symptom. Ensure the button is not being held down too long or binding against the bezel or chassis. If necessary, remove the front cover to press the button directly.
2. or else...STEP: Check the Power Button LED on the Front of the Computer (on Blinking yellow)
Initial state of LED at power up.
Indicates system has power, but the POWER_GOOD signal is not yet active.
If the hard drive LED is off, it is probable that the power supply needs to be replaced.
If the hard drive LED is on, it is probable that an onboard regulator or VRM has failed. Look at the diagnostic LEDs for further information. or lese..

3. STEP: Restart the Computer Using the Power Button.Press and hold the power button down until the computer powers off. This should not require more than 10 - 15 seconds.Press the power button to turn on the computer.
4. STEP: Verify the Power Supply Voltage Selector Is Correct for the Region. Verify the setting for the power supply:
*Unplug the power cable from the back of the system. *Press and hold the power button for at least 5 seconds to discharge remaining power.*Inspect the voltage selector setting on the back of the machine (Figure 1). Ensure that the voltage select is set in the correct position for the region the in which the system is operating: For Europe and Asia, the voltage setting should be 230V.In North America, Mexico, parts of Central and South America, and parts of the Caribbean, the voltage setting should be 115V.*Plug the power cord back into the back of the system.*Turn on the power.
STEP: Try a Different Known-Good Wall Outlet.
STEP: Remove All External Devices. Turn the system off.
Unplug everything from the front and back of the system except for the power cord or AC adapter, including: keyboard mouse monitor speakers printers scanners USB devices handheld PDAs external Zip or CD-R drives joysticks/game pads, etc
Attempt to turn the system on.
STEP: Check the Power Button LED on the Front of the Computer

Blinking Amber/yellow: Initial state of LED at power up.
Indicates system has power, but the POWER_GOOD signal is not yet active.
If the hard drive LED is off, it is probable that the power supply needs to be replaced.
If the hard drive LED is on, it is probable that an onboard regulator or VRM has failed.

Apr 25, 2009 | Dell Inspiron 530 Desktop Computer

1 Answer

Desk top


No Power, No POST, No Video
1. STEP: Ensure Correct Power Button Is Used and Is Not Sticking or Broken. If the power button remains depressed during the power-on attempt, the computer immediately powers off, mimicking a "no power" symptom. Ensure the button is not being held down too long or binding against the bezel or chassis. If necessary, remove the front cover to press the button directly.
2. or else...STEP: Check the Power Button LED on the Front of the Computer (on Blinking yellow)
Initial state of LED at power up.
Indicates system has power, but the POWER_GOOD signal is not yet active.
If the hard drive LED is off, it is probable that the power supply needs to be replaced.
If the hard drive LED is on, it is probable that an onboard regulator or VRM has failed. Look at the diagnostic LEDs for further information. or lese..

3. STEP: Restart the Computer Using the Power Button.Press and hold the power button down until the computer powers off. This should not require more than 10 - 15 seconds.Press the power button to turn on the computer.
4. STEP: Verify the Power Supply Voltage Selector Is Correct for the Region. Verify the setting for the power supply:
*Unplug the power cable from the back of the system. *Press and hold the power button for at least 5 seconds to discharge remaining power.*Inspect the voltage selector setting on the back of the machine (Figure 1). Ensure that the voltage select is set in the correct position for the region the in which the system is operating: For Europe and Asia, the voltage setting should be 230V.In North America, Mexico, parts of Central and South America, and parts of the Caribbean, the voltage setting should be 115V.*Plug the power cord back into the back of the system.*Turn on the power.
STEP: Try a Different Known-Good Wall Outlet.
STEP: Remove All External Devices. Turn the system off.
Unplug everything from the front and back of the system except for the power cord or AC adapter, including: keyboard mouse monitor speakers printers scanners USB devices handheld PDAs external Zip or CD-R drives joysticks/game pads, etc
Attempt to turn the system on.
STEP: Check the Power Button LED on the Front of the Computer

Blinking Amber/yellow: Initial state of LED at power up.
Indicates system has power, but the POWER_GOOD signal is not yet active.
If the hard drive LED is off, it is probable that the power supply needs to be replaced.
If the hard drive LED is on, it is probable that an onboard regulator or VRM has failed.

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