Need help fixing up PC / random power failures

[meshed]

Hi everyone. I was led here while trying to fix up my old pc plagued with problems. Nice to meet ya'll

Anyway, I just reformatted a Compaq Pesario SR1190CF due to various problems with BSoD's and power supply issues hoping that I would be able to somehow fix it. I'm pretty sure that BSoD's were caused by a bad RAM slot and I think I've got that sorted out.

But the main issue so far is that the power supply will occasionally get cut at unexpected moments. The harddrive, fans, etc will power down but the power button will still be lit. Also I don't seem to able to start it again straight after. Often i would have to wait awhile before the light on the PSU goes back on. Replugging the power cable only results in a crackle.

Which leads me to wonder, could my PSU be at fault? I've swapped parts out since got got it (New Graphics card, DVD writer, additional RAM) Could it be possible that the PSU just can't handle that additional strain? Could my motherboard be at fault?

opinions? suggestions? any help would be great. thanks!

oh yes my specs.

Windows XP home Edition SP2
512MB + 1GB DDR1 KINGSTON originally just 512MB
256MB Nvidia Geforce 6600GT originally an ATI radeon x1300
Samsung 22x DVD writer
Pentium 4HT 3.2GHz

Ive no idea what kind of motherboard or PSU i have. I will find out if thats needed too

Ian

 

[Abarbarian]

http://www.memtest.org/

This is a good program for testing ram.

Sounds like your psu might be faulty. Can you "borrow" another psu from a working pc ? Have you tried a different power lead ? Is the psu clogged up with dust ?

http://extreme.outervision.com/psucalculator.jsp

The above is a good tool to see what power you need for a pc.

 

[floppybootstomp]

I'd say the power supply is almost certainly faulty.

It sounds like it's overheating and a thermal switch is cutting it off until it cools down when you would be able to restart it again. Couple that with the crackling noise and it's a strong likelihood it's on the way out.

It's possible the replacement may have to be a dedicated Compaq PSU but I'm not sure, you best check on the Compaq website. Hopefully though you'll be able to fit a standard ATX PSU. If so, get a good make - Seasonic, Corsair and OCZ are good.

All cheap PSU's are a false economy so don't be tempted.

 

[TriplexDread]

Before I go any further

1. Is the computer out of warranty?
2. Are you good with a soldering iron?
3. Would you be confident to replace componants within the PSU?

If yes to all of those I would seriously consider opening the PSU and checking for issues within.
From the description you have given I would say its faulty capacitors!

When PSU is opened (DISCONNECT COMPLETELY FROM ANY POWER SOURCE) look for brownish/black goo around the capacitors, on the board or even bulging of the metal ontop or plastic below.

It will mainly occur on the secondary side (the side where wires goto PC) but check all of them if possible

The other issue could be a faulty solder joint - Also known as a dry joint. Turn the board upside down and look for damage to solder joints on all componants. Use a magnifying glass if possible. Small cracks and uneven joints can cause allsorts of issues with switching power supplies.

This is only a guide and maynot be the issue. However if you have nothing to lose why not? I always check when they cross my path....

If you do decide to have a look please, please be very careful. Electricity is dangerous!!

If you are unsure i'm sure you will know someone that can use an iron


You also asked "could it be your motherboard?" it may well be yes!

Check the capacitors on that aswell. The ones around the CPU are usually the culprit. The capacitors are easily bought online via ebay but can be very very fiddly to replace if you have not done it before.

Only advise my freind only you can decide what to do. If you are unsure then don't do it or complain if you do something wrong!!

The politest disclaimer I have ever written

 

[floppybootstomp]

I'd agree that PSU capacitors are the most likely suspect.

Many motherboards have components fitted that are 'through soldered' that is they're put into a metal 'tube' and the solder flows through this tube to both sides of the motherboard. The more common method of course being solder only on the track side of the board.

Which means they're a bugger to remove but dead easy to replace.

The tool for this is a solder sucker and preferably some desolder braid as well.

I'd imagine the machine is out of warranty judging by the spec it seems to be at least 4 years old.

 

[muckshifter]

Replace the PSU ...

 

[meshed]

thanks guys.

let me just note that my PC nearly six years old and therefore way out of the bounds of warranty and I am terrible with a soldering iron.

@Abarbarian - Yes Ive tried different power leads and yes its incredibly dusty. Thanks for the PSU calculator, I will definitely be checking that out.

@floppybootstomp - Thanks for the advice. I took a look at the manual and I doubt i need a dedicated PSU. I also found a second-hand 300watt ATX PSU online for 15NZD. It seems to been good condition though. btw are all PSU's have the same dimensions?

@Triplexdread - I've checked my motherboard and the capicitors are all fine. Dusty, but fine. I'm not going to try fiddling with the PSU. I think it'll best if I just replace it. Good side project though. I think that'll be next after sorting out my PC .