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When i turn my computer on, the monitor does not click on. i have checked all leads, and power supplies. the monitor has power light, but will not engage with computer. any ideas, please, driving me up the wall.

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I most probably thing that the tube of your monitor has busted cause there was a problem for my friend and when he took it to the repair shop they said it was the tube.....

Posted on Mar 11, 2008

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How can you check power to computer


Does your monitor light up, if so, swap the lead into the tower and if it still won't turn on then you know it's not the lead.
It could be the power supply, you could try swapping for a known working unit to check.
If still won't start, then unplug everything from the motherboard (except the power supply) and turn on. It should start making lots of beeping noises. If it does, replace each plug in turn till it doesn't then you know what to replace. If it doesn't, it's probably the motherboard that's faulty.

May 05, 2013 | PC Desktops

1 Answer

Computer turns on, but screen says no signal


Computers send out a video signal.

If the monitor isn't receiving a video signal, you get No Signal on the monitor.

First thing to check is the monitor cable. Cable is used on another working computer to verify, or known working computer's monitor cable, is used in place of it.

I believe we can skip that.
Why?

eMachines are budget computers. Designed to save the consumer money, and give the consumer a decent computer.
Problem is low cost of computer, is due to certain hardware components inside the computer, are of low quality.

The Power Supply being one.
Dirty computer inside, also leads to early Power Supply demise.

You can;
1) Test the Power Supply with a multimeter. If you do not have access to one, economical models sell for around $5 to $12.
You will be testing three main voltages;
3.3 Volts, 5 Volts, and 12 Volts. All are DC Voltage.
In comparison two D cell flashlight batteries store 3 Volts DC.

[ Power Supply's are converters. They convert the dangerous high AC voltage (100 to 240. Depends on what country you're in), to the above low DC Voltages ]

Or do you have a KNOWN to be good, Compatible power supply; you can borrow from a working computer?

(I posted this one time, and the person posted back they had borrowed a Power Supply, from their aunt. Computer sat in the garage unused. When finished they returned the Power Supply. Put it back in the computer. Then went, and bought a new one )

Before performing the above, would like you to try this;

Unplug the computer from power. Press, and hold the Power On button in, for 10 seconds. Let go.
Do this same procedure two more times.
Continue also, until the Power On light doesn't briefly flash anymore.

Now plug the computer back into power. WAIT 1 minute.
Turn the computer on. The processor fan, computer case fan/s, and Power Supply fan; should race, (High idle speed), for a few seconds; then slow down. Let's see.

For additional questions please post in a Comment.
Regards,
joecoolvette

Also post the model number of the eMachines. Some examples, T1090, W3653, etc.

Nov 19, 2012 | E-Machines eMachines Desktop PC

2 Answers

I have an old hp v75 desktop that the monitor won't turn on all the lights are working, fan running, nothing wrong with the power supply, but when I press the power button it turns on, but the monitor...


First remove the vga cable from the desktop and see the monitor shows no conection if showing there is no problem with ur monitor if not change the monitor if showing conect the cable back to ur desk to vga port then check the ram remove the ram clean the surface with clean cloth then rub the print using an eraser then insert the ram and switch on if still no display change the ram if still not working remove the processor heat sink na clean th surface of the processor and the heat sink apply a thin layer of heatsink solvent or thermal paste fix the heat sink then restart the computer

Jun 29, 2012 | PC Desktops

2 Answers

Monitor say no rgb input


Yes! I'am afraid so, make everything else is running on the computer.

Mar 11, 2012 | E-Machines T3062 PC Desktop

1 Answer

I have a dell computer. when i turn on the tower and monitor i get just a black screen on the monitor. i have pushed a few buttons on the bottom of the screen and it just says power save mode please use...


No, it's the Power Supply.

Power Supply has a weak voltage power rail.

The monitor goes to Power Saver mode because it is not receiving a video signal. (No Signal)
This is because the computer is not working.


Dell Support > Dimension 4700 desktop computer > Service Manual,

http://support.dell.com/support/edocs/systems/dim4700/sm/index.htm

Click on the heading - Advanced Troubleshooting

Is the Power On LED light blinking Amber? (Yellow)

Post back in a Comment.

Regards,
joecoolvette

{You can also test the power coming out of the Power Supply.

The Power Supply in your computer is an SMPS.
Switched-Mode Power Supply,

http://en.wikipedia.org/wiki/Switched-mode_power_supply

It converts the AC electricity from your home, or business, into DC electricity.
There are three main voltages produced;

A) 3.3 Volts (3 point 3)
B) 5 Volts
C) 12 Volts
All are DC voltage

Two D cell flashlight batteries produce 3 Volts DC.
(In case you are worried about being shocked.
The 'bad' electricity is contained inside the Power Supply's case)

If you do not have a multimeter, an economical unit can be purchased for around $8 to $12. A LOT of stores carry them. An auto parts store is one example.

Orange wires are 3.3 Volts
Red wires are 5 Volts
Yellow wires are 12 Volts.

ALL 3.3 Volt wires end at the same 3.3 Volt power rail in the Power Supply.
Same with 5 Volt wires, and 12 Volt wires.

You can test ANY Orange wire, or any Red wire, or any Yellow wire.

ANY Black wire you see is a Ground wire.

The red probe lead of the multimeter is the Positive lead. The black probe lead is the Negative lead.

The Positive probe lead is touched to a positive wire.
Orange, Red, or Yellow.

The Negative probe lead is touched to ANY black wire. ALL black wires are a Ground wire.

The function knob on the multimeter is set to DC voltage. (Dotted line over a solid line, with a dotted line under the solid line. The curved S line over a solid line is for AC voltage. This = No)

If there are different scale settings, set the function knob to 0-50 Volts. (DC)

Aug 24, 2011 | Dell Dimension 4700 PC Desktop

2 Answers

Monitor was in standby mode, computer was on. Now it shows no signal and when we try using the menu button (2) it flashes white, black, red, green, blue then a teal color.


the monitor is not receiving a signal from the computer which is why the multi coloured bars are showing. Ensure the lead is connected and is connected to the correct port of your computer. If it is connected correctly then either your graphics card is faulty or the lead, or monitor is

Apr 03, 2011 | PC Desktops

1 Answer

When i turn on my computer the screen stays black as if it's off however, the computer is working fine. Sometime it flashes on but the goes back to black.


I suggest that your computer isn't working fine, it just appears to be.

But to know for certain you need to first diagnose whether the problem is the computer, or the monitor, or monitor cable.
Do you have another monitor and monitor cable available to use for a test?

If you have a VGA monitor, (Also known as CRT. Looks like a small TV), most likely the monitor cable does not disconnect.
For this test you would need another VGA monitor with cable.

If you have a flat screen LCD monitor, most of the time the monitor cable is changeable.
You can first use a Known to be good monitor cable, then if this doesn't work, use a Known to be good LCD monitor along with the good cable.

Still no progress?

Then the problem is the computer.
Bad Power Supply. Weak voltage power rail.
One of the leading causes of computer failure.

Also from the symptom stated it matches.

With a Power Supply that has a weak voltage power rail, (Or more than one), you will have enough power to light LED lights, and perhaps spin fans, but Not enough power to turn the Processor on.

1) ALL of the LED lights on at once use less than 1 Watt of power.

2) EACH fan uses 2 to 3 Watts of power.

3) A typical Processor can use from 51 to 125 Watts of power.
Depends on what Processor it is.

This is why the computer may appear to be working fine, but in reality isn't.

Power Supply with a weak voltage power rail will run the Processor for a very short time, then not have the power to keep the Processor on.

How?
Power Supply's used in todays desktop computers are SMPS.
Switched-Mode Power Supply.

There are Electrolytic Capacitors used as Filters in the Power Supply.
They filter the incoming AC electricity, and the outgoing DC electricity to the computer components.

[ Electrolytic Capacitors are in the Input Stage, and Output Stage of a typical SMPS.

1) http://en.wikipedia.org/wiki/Switched-mode_power_supply

2) http://en.wikipedia.org/wiki/File:ATX_power_supply_interior-1000px_transparent.png

You can click on the photo to enlarge.
B shows Electrolytic Capacitors in the Input Stage of this typical SMPS. { Blue and 2 of them}
E shows more Electrolytic Capacitors used in the Output Stage ]

Electrolytic Capacitors can break down. They can operate in a weak stage as they are breaking down, for a small time period. Eventually they break down all the way, and fail.

This is how a Power Supply can work sometimes, then eventually one day it does not.

To explain Electrolytic capacitor break down, and failure:

Typical construction of an Electrolytic Capacitor;

Basic,
Three strips are rolled up tightly together, and inserted into a small aluminum 'can' case.
There is a rubber seal on the bottom of the case, and a seal on top of the case that can break open in the middle.

The three strips are;
1) A Conducting Strip
Thin metal foil usually made of aluminum. This is the Positive strip.

2) A Non-Conducting strip also made of thin metal foil, but has a non-conducting medium applied to it.

3) A paper-like strip that is soaked with Electrolytic Paste.

The Electrolytic paste soaked strip is put in the middle the Conducting strip, and the Non-Conducting strip, and all three strips are rolled up tightly.

At the bottom of the aluminum 'can' case is a synthetic rubber, flat disk shaped seal.
This is called the Bung.

There is a lead, ('Wire') going through the Bung to the Conducting strip. This is the Positive lead.
There is one more lead going through the Bing to the Non-Conducting strip. This is the Negative lead.

At the top of the 'can' case is a flat disk shaped, aluminum metal seal. This seal has an X, or Y shape etched part way into it.

As an Electrolytic Capacitor fails the Electrolytic Paste develops a gas.
Hydrogen gas.
The gas expands inside the aluminum 'can' case, and with enough pressure developed, the seal on top, and/or bottom are compromised.

The X or K shape that is etched partway into the metal disk on top, breaks open, and/or the synthetic rubber disk shape on bottom has one edge pushed out of the 'can' case.

This allows the gas to push Electrolytic Paste out of the 'can' case.
So much paste loss, and the capacitor operates in a weakened state.
Too much paste loss, and the capacitor fails.

Apologizes for the 'Windy' dissertation, but I thought it would be better to know what is going on, than receive a "Replace the Power Supply"

With No processor operating you essentially have No computer.
No computer operating = No Signal to the monitor.
(No video signal)


Need guidance in replacing the Power Supply, or suggestions for a Power Supply so you can compare, post in a Comment. (Believe upper right of your page)

Regards,
joecoolvette

Dec 01, 2010 | PC Desktops

2 Answers

I CAN SEE THE CPU FAN RUNNING, but i cannot see anything on my monitor,i mean my monitor is still in sleep mode


1) If the monitor has a removable monitor cable, and you have a Known to be good one to use for a test unit, try it. If it isn't removable, try another Known to be good working monitor.

2) If the monitor cable, and the monitor proves to be good, the next thing to suspect would be bad graphics.
Bad Integrated graphics on the motherboard, or if a graphics card is used, a bad graphics card.

3) I suspect it is a bad Power Supply. An issue that comes up so much, that I would skip 1 and 2 above, and check the Power Supply.

A) ALL of the LED lights, mumba_mwaba, use less than 1 Watt of power when in use.

B) EACH fan uses 2 to 3 Watts.

C) A typical Processor can use 51 to 125 Watts. Depends on what Processor it is.
(Older processors such as a Pentium II for example use less)

Enough power to light LED lights, and spin fans, (Or spin a few times and stop), but Not enough power to turn the Processor on.

This is why you may see LED lights lit, and fans spinning, but the computer isn't working.
The computer isn't sending a video signal to the monitor.
No Signal.

Do you have a KNOWN to be good, compatible Power Supply to use for a test unit?
May sound far fetched, but perhaps there is someone who has upgraded to a better computer, and has a computer they're not using, and you could borrow the Power Supply for a test unit.

Oct 29, 2010 | PC Desktops

1 Answer

Computer will indicate power but power light keeps on flashing, no hard drive light, no fans or anything else, power light on screen, screen black


Your computer power supply has shut down with circuit protection. Look for equipment or leads that have shorted out.
Remove all the equipment until only the monitor is plugged in.
If this works restore the equipment one by one until you find the fault.
Try this order
monitor
fans
hard drives
If it does not work with just the monitor it is either a faulty power supply or a faulty motherboard.
The Power supply is a the cheapest one to buy, to find out which is faulty.

Mar 07, 2010 | Compaq Presario 5000 PC Desktop

1 Answer

Problem getting computer to turn on


Try removing the power lead from the back of pc for atleast 15 minutes and re-connect. It may be a power supply unit fault that is showing connection but not powering the motherboard. Open up the side of pc and check the main leads that come from the power supply unit to the motherboard connection are'nt dissloged in any way, or unplug the motherboard connector and place in again this might re-set it.

Dec 18, 2006 | HP Pavilion a622n (PC108A) PC Desktop

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