dell optiplex 755 minitower wont start due ambar start button

Posted on 2014-04-09
Last Modified: 2016-11-23
Hi you experts, i have a dell optiplex 755 minitower and when press start buton goes ambar and no start, no bleeps either, i supposed was the power source, i change it but the same, wont start and the power button is in ambar,
any advice you experts?
Question by:edo60
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LVL 10

Accepted Solution

Korbus earned 150 total points
ID: 39989364
I suggest you start by removing all installed components, and see if you can boot up.
The motherbard controls the power to the system, the button you push simply sends a signal to  the MB.  If the MB or one of it's components (like RAM) is having trouble, it may not allow the system to power up.

If the problem continues with all devices and memory removed, this indicates a motherboard problem, and it will probably need to be replaced.
If the system starts up with all the components removed, start adding them back, one at  time to see which device causes the system to fail to boot.  Then replace that one component.
LVL 25

Assisted Solution

by:Tony Giangreco
Tony Giangreco earned 50 total points
ID: 39989365
Remove all the add-in card, reseat the ram chips

Try and turn it on again. if the Amber LED lights, then the PS is probably dead. there is a slight chance the MB may be damaged, but if it has not been touched and the system has been connected to a UPS or good surge protector, then it's probably the power supply.

I suggest purchasing one from dell or a rebuilt dell PS so it fits properly and works as expected.

Author Comment

ID: 39989408
oh man, so bad news, i remove ram, and hd, and ambar still there, i also change the power supply and ambar still there.
what can i do?? some one says me could be the integrated video card, is that posible?
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LVL 17

Assisted Solution

pjam earned 50 total points
ID: 39989422
Manual says motherboard if you already replaced power supply:
Solid yellow The Dell Diagnostics is running a test, or a device
on the system board may be faulty or incorrectly
If the Dell Diagnostics is running, allow the testing to complete.
If the computer does not boot, contact Dell for technical assistance
(see Contacting Dell).
Blinking yellow A power supply or system board failure has
See Power Problems.
You can find all the manuals here:

If you have a compatible video card you can try that, but not too hopeful.  Sorry
LVL 62

Assisted Solution

by:☠ MASQ ☠
☠ MASQ ☠ earned 50 total points
ID: 39989443
The 755 has 4 diagnostic LEDs on the back which may help if the board is still getting power. Check if any of them are lit.  Unfortunately a huge batch of these boards built by Foxconn had a bad batch of capacitors which is a known weak point with this model, despite it having reached a respectable age for a PC. The amber power button LED can also indicate a fatal motherboard failure :(
LVL 27

Assisted Solution

by:Jason Watkins
Jason Watkins earned 50 total points
ID: 39989444
Amber power button = dead power supply in my experience.
LVL 10

Assisted Solution

Korbus earned 150 total points
ID: 39989451
One last thing I would try before declaring the MB dead:  reset the CMOS (this is the memory that BIOS uses when starting up the machine).  The manual should have instruction on how to do this.

If this does not help:
If the video card is integrated with the motherboard, you cannot separate out that component.  
I'm afraid it looks like a your motherboard has gone bad, and will need to be replaced.  You mentioned you recently changed power supplies,  it's probable your old power supply damaged the MB on it's way to the grave.

Next step: give Dell a call about getting a replacement MB- they MAY have some other things you can try first.  How old is the system, perhaps the MB is still under warranty?

P.S.  I am making the ASSUMPTION that since you just replaced the PS, the new one is working properly.  This might not actually be the case.

Author Comment

ID: 39989569
mother board looks good,
is 6 year old pc

Assisted Solution

by:Hassan Besher
Hassan Besher earned 50 total points
ID: 39989579
i happened to me once and it was mother board :(

Try to use the motherboard on working PC with the same model or compatible to see How it's going .
LVL 18

Assisted Solution

web_tracker earned 50 total points
ID: 39990539
If you have already replaced the powersupply with a known good powersupply, it mostlikely is a problem with the motherboard. If you have a video card you may try that first, because on these dell computers if you plug in a video card it will automatically disable the onboard video card, so if the onboard video card is shot it should power up using a video card. If the video card does not resolve the issue it looks like something else is dead on the motherboard. Since the system is so old it obviously is out of warranty. Looks like the computer is ready for the grave yard as the system is not worth replacing the mobo it is too old. Mostlikely the system was running windows xp anyway which is now beyond support by MS. So it is probably better just to replace the computer, which will come with a current operating system.
LVL 10

Assisted Solution

Korbus earned 150 total points
ID: 39990552
Did you reset the CMOS?

The MB may LOOK good, but the problem could be inside one of the IC's where you can't see it.
I guess the question is how much effort do you want to put into getting it repaired?  If you cannot get the MB from DELL, you can try ebay or something like that.

At this point (assuming you reset the cmos), I would probably play Taps for the old guy, and get a new PC.
LVL 92

Assisted Solution

nobus earned 50 total points
ID: 39991191
these boards are known for bad capacitors :
here a youtube :

here's how they can look :

***note that the PS can have bad caps too !!

Author Closing Comment

ID: 40018122
it was the mother board

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