No beeps!!!

[venkatbabukr]

Hi,

I have a PC that is around 3 yrs old. The system configuration is as follows: PIII 650 MHz processor, 128 MB RAM, Mercury KOB 810 DST mother board (with inbuilt audio and video cards).

Few days ago, all of a sudden, when I switched on my PC it didn't boot!!! In fact, it is not even performing POST coz I'm neither getting any beep nor anything is displayed on my monitor. I could find on the net that this problem may be related to power supply, but I guess my power supply is working fine, coz the processor fan and motherboard fan work properly, also, the system's LED glows.

I couldn't find mention of such problem any where!!! Can anybody help me in identifying what is the problem with my system and how to solve it.

Thanks in advance,
Venkatesh

[Sylvander]

Download a copy of my diagnostic flowcharts from here
www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.

Begin on the START UP chart and follow the instructions.

[ziba-june]

There are a few things that could have gone wrong with your system and power supply might be one of them. The fact that your power supply is running the fan dosen't say it is good. Powere suply is connected to one of the Processor's wire and unless the processor gets enough juice, it is not going to wake up. So to be sure that the problem isnot with your PS just test it with a multimeter and then you can go to other testings.

[venkatbabukr]

Hi,

Thanks very much for the replies...

Think some thing is wrong with the system board, coz even the diagnostic flow chart says this is a problem associated with the system board... I'll try to find out whether the powersupply to the processor is working properly.

But, Sylvander, Just for my information, how can we troubleshoot problems associated with system board... I mean, can we get something like the diagnostic flow chart??? BTW, the diagnostic flowchart is really cool :-)

regards,
Venkatesh

[Sylvander]

I don't know enough about motherboards, and the testing hardware I have heard of is rather specialist, but you could look here
http://www.fonerbooks.com/pcrepair.htm
for sets of charts including this one
http://www.fonerbooks.com/cpu_ram.htm
on Motherboard, CPU, RAM failure.

That shows you the few things that the non-expert can check.

[Sylvander]

TESTING ATX POWER VOLTAGES

See this http://www.pcguide.com/vb/showthrea...=&threadid=8680
Then the below, here http://www.pcguide.com/vb/showthread.php?s=&postid=152496#post152496

Black = ground
Red = +5 volts
White = -5 volts
Yellow = +12 volts
Blue = -12 volts
Orange = +3.3 volts (?)
Green = power on

Turn the power on. The fans should at least come on so that you know you have power.

Turn on the voltmeter and set it to measure DC voltage. Start with an IDE power connector that is not used. Place the black lead of the voltmeter in the hole of the connector that has a black wire (ground). Connect the red lead of the voltmeter first to the yellow hole and then to the red hole. The voltmeter should read +12v and +5v respectively.

The other voltages may usually be measured at the motherboard power connector by simply sliding the red multimeter test probe down the hole where each colour wire goes (with the black probe connected to any black wire as before). Really you only need to check the orange wire for 3.3 volts at this connector. If +12, +5, and +3.3 volts are all okay, then your power supply is probably fine.

Unfortunately, a low voltage measured in this way may mean a bad PSU or that some other component (motherboard, etc.) has a short and is pulling the voltage down. Therefore, the main value of measuring voltages is to eliminate the PSU as a source of the problem (if it has normal voltages).

[rond36]

The other voltages may usually be measured at the motherboard power connector by simply sliding the red multimeter test probe down the hole where each colour wire goes (with the black probe connected to any black wire as before). Really you only need to check the orange wire for 3.3 volts at this connector. If +12, +5, and +3.3 volts are all okay, then your power supply is probably fine.

Unfortunately, a low voltage measured in this way may mean a bad PSU or that some other component (motherboard, etc.) has a short and is pulling the voltage down. Therefore, the main value of measuring voltages is to eliminate the PSU as a source of the problem (if it has normal voltages).

Chances are good that your PSU is an ATX and you need to use a jumper wire from the blue -12V terminal to any black ground to turn the PSU on so you can check the voltages. P III boards don't have the extra 4 pin connector that a P IV has, the motherboard can't be a component that is pulling the PSU down because the power is unplugged from it.

[Marzman]

Just a quick post speaking from experience. I have the same problem and i had the cpu tested and thats fine so it looks like it has to be the motherboard, so venkatbabukr, your hunch about the system board might be right

[venkatbabukr]

Hi all,

Thanx for all ur inputs, the problem got resolved... but the solution is a kind of interesting: I just erased the CMOS and things started working well...

Don't know how and why the above worked.

-Venkatesh