Possible motherboard problem?

[Barb and Ray]

We are working on an eMachines computer to see if there is any possibility
of saving it. This area had a bad heat spell last summer (110-115 degrees)
and the air conditioning went out for two weeks in the home where it was
located.

Computer was working fine prior to this. Have found the power supply is
kaput, put in a different one that we knew was working and it tests OK,
however, when plugging into the motherboard, nothing is happening, no CPU
fan and no power supply fan.

Is there anything else we could try before shucking it?

Thanks for any help you can give.

 

[Office 2004 Test Drive User]

Pull the modem, memory, cmos battery, and unplug all drives..

See if it'll turn on and beep.. If not, u can pry salvage hdd's and ram...
But mobo is bad

We are working on an eMachines computer to see if there is any possibility
of saving it. This area had a bad heat spell last summer (110-115 degrees)
and the air conditioning went out for two weeks in the home where it was
located.

Computer was working fine prior to this. Have found the power supply is
kaput, put in a different one that we knew was working and it tests OK,
however, when plugging into the motherboard, nothing is happening, no CPU
fan and no power supply fan.

Is there anything else we could try before shucking it?

Thanks for any help you can give.

Sent using the Microsoft Entourage 2004 for Mac Test Drive.

 

[R. McCarty]

How recent an eMachines PC ? If 3 years old or more I wouldn't
put any more time or money into trying to resuscitate it.

 

[AJR]

Problem may still be the power supply. If the computer is "fairly" young -
motherboard/power supply are ATX - power is supplied to the board at all
times (5 volt supply)- even when computer is turned off.
ATX power supplies cannot be "checked" without being plugged into the board
(must have a "load" for correct voltages). Off and On are software
controlled, not hard wired to power button (why you must hold power button
in for about 5 seconds to turn computer off)- pressing button uses the 5
volts to "turn on" power supply.
Most newer boards have a LED which indicates presence, or absence, of the 5
volts.

 

[DanS]

Pull the modem, memory, cmos battery, and unplug all drives..

See if it'll turn on and beep.. If not, u can pry salvage hdd's and
ram... But mobo is bad

That's a good call. I've seen more than one dead HD that can cause this.
There may be a very short flicker of the LED the first time you try to
power it on, but it is easy to miss.

 

[w_tom]

Notice an accuate post from AJR. Others posted 'try this and try
that'. Nonsense. Take measurements. Get a definitive answer the first
time and in but a minute. As AJR implied, a power supply is only one
component of a power supply 'system'.

3.5 digit meter would have answered your question in but minutes. In
your case, first measure voltage on purple wire (from power supply to
motherboard) when computer is off but connected to AC wall receptacle.
(note: we have now demonstrated why power cord must be disconnected
before making or breaking any connection).

Purple wire voltage must be more than 4.87. Then measure voltage on
green wire. With computer powered off, it would measure more than 2
volts. When power switch is pressed, that voltage must drop below 0.8
volts. Gray wire would be near zero and then rise to well above 2.4
volts within seconds of pressing the power switch.

Finally, when computer should be on, measure and report voltages on
any one of red, orange, and yellow wires.

LEDs can light. Fans can spin. And still something in a power
supply system is 100% defective. How do you find a defect? Meter. In
but minutes.

Posting those numbers here provides enough information for replies
that identify suspects, define what is good and working, and what to do
next. Notice no "it might be this and might be that' answer. Numbers
provide a definitive answer. Get that meter. Get those numbers. Get
a useful answer immediately.