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Bad Motherboard? Help Troubleshooting PC

I'm not very experienced troubleshooting PC hardware. I have a computer (4 year old Celeron 1.3) that started crashing a couple of days ago. If I waited long enough to restart it the PC would be useable for a couple of hours before it crashed again.

Today it crashed and didn't come back on.

I opened the case and powered it on. The CPU fan didn't come on. My first feeling is that the CPU overheated and powered the PC off . . . and maybe eventually cooked? How do I test a CPU? Put it in another machine?

Anyway, the HDD powers on, an extra fan I have powers on (when plugged into the power supply)and the on/off switch on the PC works just fine.

I tried connecting the extra fan I have to the main board in 3 different locations (all fan power outlets) and it didn't come on. I used my meter to find out the following:

Power supply is putting out 25.5V (read at one of the connectors used to plug into the HDD or CD-ROM drive). I tested by putting the positive lead into the 12V feed of the connector, and the negative lead into the ground feed of the connector.

The fan outlets on the main board each read 9.9 -10.1V. Seems to me they're a little short power but only 2V or so,right?

One more thing, when I power the PC on, nothing happens with the "stuff" that's connected to the motherboard (processor too, right?) - we know that - I mentioned it before. However, when I pull the plug on the PC to turn it off - the fans connected to the main board briefly power on.

What does all this mean? Is the mainboard shot? If so, why does it read any voltage at all? Is the power supply shot? Maybe it's putting out too much voltage?

Please help. I'm a total NEWB with hardware troubleshooting.

Thanks,

PO

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don't want to sound flip...

In reply to: Bad Motherboard? Help Troubleshooting PC

...but if you've got a celery 1.3, just upgrade to a new pc or laptop. $400-500 will get you a much better pc and since your hard drive is OK you won't lose any data. a new power supply could run you $50, a new mobo about as much, and neither may solve your problem.

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Two relatively simple things

In reply to: don't want to sound flip...

You can go to http://www.pricewatch.com and find replacement Celerons for around $10. Go to http://www.computergeeks.com and get power supplies in the $20 range.

Remove/replace [substituion] is really the only effective way to fault isolate between CPU, PS, and mobo.

Another possiblity for the 25 volt reading could be that you were on an AC scale rather than a DC scale.

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CPU fan

In reply to: Bad Motherboard? Help Troubleshooting PC

I, too, would consider a new computer; however, you might just need a new CPU fan to get this one healthy.

Get a free utility program to monitor fan speds and CPU temps (SpeedFan is one example). Run your computer with the case open. Watch your CPU fan as you start your commputer. Observe the CPU fan speeds and CPU temps.

You might just have to replace the CPU fan--an inexpensive fix.

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Four years old?

In reply to: Bad Motherboard? Help Troubleshooting PC

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If your power supply is putting

In reply to: Bad Motherboard? Help Troubleshooting PC

out 25 volts on the 12 volt line, everything on that line should be fried. I suspect that your measurement is incorrect or being used incorrectly. The fans should also read 12 volts [from the same lines] unless they are plugged into the mobo via the three pin connector. If connected to the mobo then the voltage on the meter could read virtually anything if using a a DVM. Depends on the A to D design in the meter. That is because the 12 volts to the fans are being turned off and on [modulated] as the means of varying the fan speed in accordance with the temperature. The meter's A/D search algorithm will cause it try to find a steasdy value, but fail.

The 25 volt reading could be caused by your meter leads not actually being connected to the 12 volt and its return, or some such anomaly.

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Another note re

In reply to: If your power supply is putting

possible 25 volts. There is a MINUS 12 volt output on an ATX supply. No longer used, however it is there. Thus if you had one meter lead on the PLUS 12 volts and the return actually on the MINUS 12 volts, instead of ground, something near 25 volts would be read.

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My meter work

In reply to: Another note re

Yeah, I guess I'm not that great with the meter. I included the voltages but was more focused on the fact that power was actually getting to/through the board. Micro ATX board. There are 2 black wires, 2 red wires, and yellow wires. I probably did as you suggested (considering I've never done this before) and screwed up the reading. Also, the reading I took at the fan connection was at a 3 prong connector.

For the record, purchasing a new PC is out of the question. It's not my money to spend (I'm looking at this for someone I just didn't explain the whole situation.) And $50 is a lot easier pill to swallow than $500.

As for the troubleshooting. . . where do I start? Could the board be bad even though power is running through it?

Thanks,

PO

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Board or Chip . . . the age old question

In reply to: My meter work

Alas, I feel for your position. I only recently extracted myself from the same one.

My friend of 20 years delivered to me her PC's lifeless body, and I had to figure out if the board or the chip was fried (or both). She had a 3 year old 1.8 ghz system that I had previously changed the power supply and hard disk on. Unfortunately, her fans were all bad, and the system overheated.

I have been told that it is pretty difficult to determine what component is broken (board or chip) unless you have working spares available to you. At that point you can simply put a spare chip in the old board. If it works, great! If not, try the old chip in the spare board.

Obviously most people don't have spare motherboards or chips lying around. In my case the decision was made easier because to replace either component would have cost $200 for identical parts. On the other hand, it only cost me $250 at Micro Center to replace the board, the chip, the fans, and the RAM. For that price I esentially got a brand new system with much better speed.

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find a local guy

In reply to: My meter work

Try finding a local PC shop (not a large retailer like Best Buy or a business machine depot like Entre Business Systems) or local used parts dealer. They'll probably be willing to diagnose your problem for free assuming you'll be buying the replacement part from them. They can do in 15 minutes what will probably take you a few hours, so I recommend saving yourself time and frustration.

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Troubleshooting M/B issues

In reply to: Bad Motherboard? Help Troubleshooting PC

First ... Power Supply --> you may be reading the meter correctly if the P/S has a short, use w/extreme caution.

Second: Caps have been mentioned, I'LL mention them again. If they are leaking or crowned STOP. Nothing you can do except waste time and hair.

Too Trooubleshoot -->>
Remove all components from the M/B except the speaker, power-on switch, CPU and CPU fan.

Turn systen on, if you hear a beep or a series of beeps, then your CPU is ok.

Attach monitor, on-board or video card, again you should hear beeps. No beeps damaged video controller if on-board or bad card.

Memory is last. Try one slot then the other. I system beeps the memory slot or slots are damaged. No beeps you should see the post screen.

Add on compoment at a time from here, allow system to boot any failure replace that component.

Luck

Bill

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Thank you!

In reply to: Troubleshooting M/B issues

Bill and Ray, thanks for the advice. I was going to pose this question to Ramarc: What will the local guy do to figure out my problem in 15 minutes?

- but I think you answered it Bill. Thank you. I started from scratch today by swapping out the power supply. CASE CLOSED. I'm not sure if I'm good enough to do it any other way than by process of elimination but the process worked.

And, evidentally, I was on the right track according to Bill's list.

New post coming soon. WEIRD power issue in this one.

My sincere thanks to those who guided me to the solution. I prefer DYI.

PO

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glad you're up and running

In reply to: Thank you!

a local repair shop will have spare parts laying around, so he could just plug in another PS to your board without you even removing the old one. ditto on the mobo/ram. just pop it into a spare that he knows is working.

for instance, my laptop's dvd drive starting acting flaky. sometimes, it would work, sometimes it wouldn't. the problem was most like the drive, but it could have been a power supply or mobo connector issue. the repair tech opened up my laptop, took out my drive, put in a spare, and in 10 minutes we were sure it was drive. it would have taken me hours of googling just to know there was a hidden screw on the bottom of laptop (along with the two inside the laptop) that needed to be removed before the drive would pop out.

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Good to hear

In reply to: Thank you!

you are up and running.

As far as process of elimination and not being good enough, not so. I repair computers for a living, post here to test my knowledge, learn and help where I can. Ramarc actually posted what I would of done first. If that failed then the steps I outlined to you would of been performed.

Go to Computer Repair with Diagnostic Flowcharts scroll down to Boot Failure Troubleshooting Poster. A little weak but gives a good process of elimination example.

Bill

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Beeps on M-boards

In reply to: Troubleshooting M/B issues

I just wanted to add that I've had quite a few boards that made no sounds, whatsoever- no matter what was or wasnt attached-- & they worked just fine.

As that rig is a 1+ Celeron & that vintage, I'd have to concur it would be money better spent to simply upgrade now. I'm all for troubleshooting, but this one falls into the "sounds pretty bad" catagory. To save $$ (thinking it may be a lost cause) a lot of folks end up getting a cheap PS (bad) & work like mad for nothing.

If you truly want to try to ressurect this one, however, buy a good power supply w/the thought in mind that if that isn't the "fix" you have the idea that you'll get the new board/CPU/RAM (case, too, most likely) & utilize the nice, new PS in that build.

Tracy
Here's a good deal on a super case:

http://www.antec.com/us/productDetails.php?ProdID=81046

Choose "buy in US/CA" - $78 shipped. Has a great 400wt. PS, too. Reg price online is $110-140.

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Power Supply

In reply to: Bad Motherboard? Help Troubleshooting PC

Before you go crazy spending money that you do not need to, try to borrow a known good power supply from someone and try your pc again. I do not know where some of these guys shop, but a perfectly adequate power supply can be had for less than $20 from many on line vendors, or even a local computer show.

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