Power problem

[peterpan271]

Hi, i'm a newbie here and i have made quite a round of some of the threads to make me inspired to tinker with an old motherboard and power supply. the power supply is Amax LC-A300ATX and the mobo is L4S5M/DX. The problem is when power is put on from the avr the cpu fan immediately runs for about 30 secs and then stops. When i pushed the start button of the pc the fan resumes and again stops after approx the same period. Is this a power supply problem? if not what could i do to fix the mobo? Any help would be appreciated, thanks. ED

[c_hegge]

Re: Power problem

Try a different PSU. If it doesn't help, then the problem is with the board.

[peterpan271]

Re: Power problem

Try a different PSU. If it doesn't help, then the problem is with the board.

Thanks, ......I,ve tried another PSU, and the same problem exist. What could i do with the mobo?

[c_hegge]

Re: Power problem

I don't do that many repairs on motherboards other than caps and in one case, a coil and a VRM MOSFET. Wait for someone with more experience repairing motherboards to chime in.

[peterpan271]

Re: Power problem

I don't do that many repairs on motherboards other than caps and in one case, a coil and a VRM MOSFET. Wait for someone with more experience repairing motherboards to chime in.

Ok, hoping somebody might drop by. Thanks again.

[everell]

Re: Power problem

Welcome to the forum. Don't know that I can help too much, but here are a few pointers. Do you know that one of those power supplies is good for sure, or are both unknown? The original one with LC in the model number could be a Solytech, which isn't much on quality. You did not mention who the manufacturer of the mobo is. Some may know from Model number alone, but most probably don't.

If you post some pictures, it is often helpful. The guys on the forum have sharp eyes when looking at the pictures and can often spot a problem.

It would also be helpful to put a general location in your header so we will have an idea as to where you are, and who the best vendors for parts will be in your area.

For the fan to run about 30 seconds and then shut down may indicate a heat problem. You might try cleaning the heat sink and cpu and reapplying thermal compound. Sometimes an older board has old goopy junk that isn't working very well, and the heat sensors might be shutting things down. Bad capacitors are the number one suspect. Look for any bulging capacitors. Without knowing anything about the history of your mobo, it could be a bad cpu or south bridge chip.

I would start with looking for bulged capacitors and post some pictures, include Manufacturer as well as model number.

[peterpan271]

Re: Power problem

thanks @everell.
the mobo is from Elite Group(ECS), I will try to snap some pictures for reference view, meantime im going to check on areas you have mentioned to look for possible defects. i will post later on whatever developments.
i have also included my location on the header as you have suggested.
thanks again,
ED

[bigbeark]

Re: Power problem

The manual is here: http://www.ecs.com.tw/ECSWebSite_200...uID=82&LanID=0

This board support 533 FSB. You must use a 400 or 533FSB CPU. Lookup your processor on www.cpu-world.com.

If the board detects somwthing about your CPU it doesn't like it will shut itself down.

Check that your CPU fan is connected to the CPU fan header - NOT the case fan header. Board will also shut down if CPUfan connected to the wrong header.

[peterpan271]

Re: Power problem

Found the culprit on the power problem: a shorted panel power button. That's the reason for the immediate power on upon putting in power from the avr. Replaced said micro switch and the power is okay now. However, the new problem is no video on the monitor (remains blank), only blinking power light on the monitor now. The monitor is sure to be in good order, been tested okay with other pc already. Same with the video card, also been tested okay on other motherboard. I'm attaching 3 pictures of the mobo for reference, not much on the resolution, though, i'll try to get better pics later.

[everell]

Re: Power problem

That mother board has an on board video....so remove your video card, and plug your monitor cable into the video connector on the mother board. Then power it up and see if you get some video.

[peterpan271]

Re: Power problem

That mother board has an on board video....so remove your video card, and plug your monitor cable into the video connector on the mother board. Then power it up and see if you get some video.

The mobo has no onboard video, as shown by the attached diagram from the manual.

[c_hegge]

Re: Power problem

Another suspect could be the capacitors. They look like OST, which are notorious for failing without showing any visible signs of it.

[peterpan271]

Re: Power problem

Could it be possible that the defective case panel power switch had damaged the motherboard? If so, where in the mobo could it possibly affect directly, thereby causing failure in the mobo systems?

[everell]

Re: Power problem

The mobo has no onboard video, as shown by the attached diagram from the manual.

My mistake.....it just looks like the kind of mother board that would have an on board video.

Looking over the over the manual a little this time........your AGP slot will do 4X video cards. Boards of this vintage often have a setting in bios for 4X enabled or disabled. Since you don't know what the setting is, I would start by resetting the cmos.

First, pull the cmos battery and check voltage. Replace battery if needed.

Next, with computer unplugged from wall outlet, reset the cmos using the jumper pins.

Once the cmos is reset, the computer will look for a video card in one of the pci slots which is the default setting. Try using a pci video card rather than a AGP card and see if anything comes on.

My experience with "do nothing" boards has been that sometimes a mother board is particular about what kind of video card will work. I have found that trying several cards will sometimes get the computer working. Some pci cards work, and some don't. Some agp cards work and some don't.

Next, if the cpu is dead, nothing will happen. I use a cheap post tester that I found on ebay. The first number at power up is FFFF. If you get FFFF and nothing else, the cpu is dead. If you get a whole bunch of changing numbers, then your cpu is alive.

Next, power surging can cause a bios chip to go crazy. I have fixed a couple of boards by having the bios chip reprogrammed.

Finally, a bad north bridge chip or south bridge chip, or some other component bad would be bad news. Thats when the board goes to the dumpster. A good test to see if the south bridge chip is working is to turn computer on, and let it run a minute or so. Fans should be running. Then hold the power-on button in. The fans should continue running for about four seconds, then turn off.

[peterpan271]

Re: Power problem

@everell
thanks, i'll take your recommendations, post the developments later.