No LED or display on the Monitor

Posted on 2006-03-31
Last Modified: 2010-04-26
Swap the monitor - it works on another PC.
Take a working Monitor and plug it into the bad computer
you see the same symptoms: No LED or display on the Monitor.

The bad computer is two (plus) years old.
The Power Supply is suspect.

We barrowed an "ULTRA" Power Supply Tester.
Here are the Test results:
20-pin connector.  All LEDS light up except
one, LED (-5V) doesn't light up.

HDD & Floppy test results: All lights light up (+12V & +5V).

The P4 connection test result: Only the +12V LED lights up.
the other, LED (+5V), doesn't light up.

We'll replace the 200 Watt Power Supply.

Will replacing the power supply solve the
"No LED or display on the Monitor" problem?
 Reading other posts, we are beginning to think the motherboard may be at fault.
Is this a common power supply failure symptom?

Finally, How long should the computer "last" after the
power supply is replaced?  We always thought losing the power
supply was just a harsh reminder to replace the the computer.

Question by:SmithRiver
    LVL 13

    Accepted Solution

    There's no concrete answer here, but my observations and comments are:

    1) I suspect your power supply is not sufficient.  200W?   May or may not be good enough, based on your computer specifications.  By "today's" standards, a typical PC hat at least 350W, usually 400 or more.

    2) The behavior you are describing sounds like a failed video card.   If you are using "integrated" video (part of the motherboard), then yes, you will need to replace the motheboard......    Your power suuply is probably ok (but perhaps a bit on the weak side..)

    3) Lack of video is NOT a common symptom of a failed power supply.  Lack of video means no video signal, which means bad graphics card or bad integrated graphics, or bad motherboard.

    4) A computer can "last" as long as you want it to--  it's only obsolete if YOU cannot do what you want on it.   For me?  I usually overhaul my pc every 24-30 months.    For my wife?  She's using a PC our office threw out almost 4 years ago.    It all depends on the user.
    LVL 1

    Expert Comment

    Replacing the powersupply will only fix the monitor problem as long as the main computer components were not wrecked along with the powersupply going bad.

    If the bad power supply did not wreck the mainboard or vice a versa, then the computer should run for many years after the new power supply is put in.

    Author Comment

    Any ideas on what would cause the "integrated" video
    to suddenly die?

    No physical modifications
    have been done to the computer since February of 2005.
    (Back in Feb '05, the hard drive was replaced
    with an identical 60 GB hard drive.)

    The only software added to the machine recently
    was a common tax preparation program.

    Was it just the computer's "time to go?" :o)

    LVL 13

    Expert Comment

    Well, things happen.    I bought a store-brand PC for my son last Christmas, and it had a micro-atx name-brand motherboard in it.

    After only having the system 5 months, the system started displaying icky behavior--  blue screens, all sorts of other things - and after much testing on my part, I deemed the motherboard had just gone bad.

    I was right- replaced it- all has been perfect since.

    ONE possibility that may be visible is that your motherboard could have been a victim of the "bad capacitors" of 2 years ago.     Several motherboard vendors used caps from the same vendor- and it affected thousands of motherboards when the caps went bad.    Look inside, CLOSELY--  maybe with magnifying glass-  a bad capacitor will reveal itself by showing like it "puffed up" a little bit, or leaked.

    That aside, things can just go, due to imperfect manufacturing, a static charge or power surge that you may be unaware of--  lots of things.      Some motherboards will last *YEARS* - others may fail within 1 year.    My guess is - you're out of luck, since you're likely beyond the warranty period.

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