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Old computer D_ _n thing won't start, HELP

By bouncy64 ·
I have 2 different computers, they have working components(as best can tell), and yes i checked the battery and they are fine,all plugs are where they are suppose to be, and the right way, the problem is i can't even get the bios to come up on either, the one was suppose to be a simple job of reformatting the hard drive, and worked fine a month prior, just the owner wanted to upgrade to win98 from win95, i have tried with two different monitors that i use on two of my older computers, i have switched out the vid cards and still no bios, the monitor acts as if there is nothing connected to it, the ram is fine also as both use sd ram, and i have checked the ram in another computer and is fine, one more thing i have checked the cpu's and they work fine in another comp, they both sound like they are "firing up", the sound of the hard drive and the lights flicker briefly as well as the keyboard,everything normal but no pic, like i said i tried switching out the vid card, and yes i know it is a good vid card, tried just about everything, any help would be great thx.

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Some Thoughts

by TheChas In reply to Old computer D_ _n thing ...

Hi,

Since these systems had Windows 95 on them, I assume that everything is at least 8 years old.

Swap in a known good power supply, or measure the output voltages with a good meter.

Back in the early days of SDRAM, there were a lot of strange restrictions on many motherboards. If you changed or added RAM, switch back to the original RAM and see what happens. The list of strange restrictions I ran across back then could fill a book. Common limits were 32MB per slot, single density RAM only, and a 16MB limit on all slots when using the third slot.

I assume PCI video cards. There should not be any issues there.

One thing that trips people up from time to time is that some drives have different jumper settings for master with slave and single drive.

The boot sequence you describe is very similar to booting up some drives set as master when they should be set as single.

Chas

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Double check the power supplies

by mjd420nova In reply to Old computer D_ _n thing ...

You have two voltages to check, one is the 12 volt, that runs the fans and drives, the other is 5 volts and runs all the boards. The drives could sound like they are turning, but without 5 volts, nothing will start. Most often something is shorting the power supply, the lights will flicker and the fan tries to start but stops, that's a sure sign.

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they both sound like they are "firing up"?

by NOW LEFT TR In reply to Old computer D_ _n thing ...

CPU does not make a 'noise' - thats will be the fan!

Motherboard?

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Power supply or motherboard

by --Loki-- In reply to they both sound like they ...

I had a similar experience recently with an older Gateway machine. the fans came on, lights on front came on... But nothing else, no matter what....


I took EVERYTHING out.. Including the motherboard... and began looking at the motherboard carefully. .... Near one of the serial ports, a tiny component of some sort had been partially scraped off of the board. Power was going through the board, but never getting to the components it needed to, due to this damaged component. It was nearly invisible while it was still in the computer case, but once taken out of the case, it wasn't hard to find.

A clue to this, that made me take everything out like that, was that although the hard disk and the cpu fan was getting power, the heatsink on the cpu and the heatsink for the voltage regulators near it stayed ice cold. they should have begun getting a bit of warmth to them as soon as the system powered on if power was getting to them.

Another clue, was that the lights on the keyboard didn't light up when the system was powered on. So it wasn't simply a video or bios issue... it was never getting that far.

Now on an entirely different system.... It would power up, it would even do simple dos based tasks that were not intensive, including formatting and copying files. but the windows OS would not install or load AT ALL... It would get through the file copying part, which is not cpu intensive, but then when it began configuration, it would instantly reboot, and any attempt to load the OS would cause it to reboot.

Using a boot disk, all the obvious scans were done, with no problems found. A memory burn in test was fine, all the hardware reported in that there were no issues when doing a basic diagnostic.
BUT when a cpu burnin test was done, again, instant reboot.

Sooooooo... initially I tried replacing the processor, with no change in the problem. So I took a closer look at the motherboard with a flashlight. I noticed that a couple of the voltage regulator caps (the cylinder shaped thingys sticking up near the cpu socket) were bulging, and one looked as if the top was leaking rusty colored stuff. Well, that answered that question... lol... without the voltage to the cpu being regulated, it ain't gonna work under any sort of load.

So again, it was a motherboard issue.

But in your case, it seems to me that there's either a faulty power supply, easily tested by simply taking a known good power supply and attaching it to the board and hard disk(dont' even have to actually install it in the case, just to test this)

OR there's a scratch on the motherboard or a damaged component on the motherboard, that's not allowing power to the cpu.

Look for scratching near the cpu fan clips, look for blown voltage regulator caps, look for bits of metal filings near the screws if a screw is stripped, take the motherboard out of the case and attach a powersupply and see if you can get it to boot out of the case, and if so, look for an area that the case might be shorting it... look for any little square thingys knocked loose or missing from the board (for example, if it's obvious that theres supposed to be several in a row, but one is crooked or missing)

That's about all I can think of at the moment... Hope it helps!

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Did you

by zlitocook In reply to Old computer D_ _n thing ...

Reset the BIOS by jumper? Check the mainboard website to see how to do it. I still have a 800 Mhz that when I change memory or hard ware I have to reset it.

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Inspect Caps

by willcomp In reply to Old computer D_ _n thing ...

Check capacitors on motherboards for signs of swelling or leakage. Here's what to look for:

http://www.badcaps.net/ident/

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thanks for the help

by bouncy64 In reply to Inspect Caps

prob was located with the cap idea when inspected i had missed this and unfortunatly the motherboards had more than one black spot on them and it looked like this had happened more than once with the second one, once owners informed they were gracfully retired to motherboard heaven as they were p2's and well, lets just say the peices are now installed and running happily, again thanks for the idea's and your time and bother, Bouncy64 :)

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