Dead pc.

[tellietubbie]

Hi all.

A couple of days ago while surfing the net my pc froze,(mouse no

 

response) so I tried ctrl alt del in the hope that taskmanager would

 

appear and let me close the browser.no response and then the whole

 

thing died.It wouldn't switch back on so I decided to take a look

 

inside suspecting the psu.PSU fan wasn't working so I removed the unit

 

from the pc case then put a link from the green to black on the 20 pin

 

plug.The fan started up ok and all voltages measured correctly using a

 

dvm.I then turned my attention to the on/off switch on the front of the

 

pc case, this operated correctly using the continuity setting on the

 

dvm. Its at this point that I'm unsure as to what the fault is but I

 

suspect there must be a latch of some type on the motherboard which is

 

operated by the main switch I tested.(just a wild guess!)

Given that the psu operates and the on/off switch operates I started

 

looking at the motherboard and saw a total of 5 electrolytic capacitors

 

which are bulging at the top, a problem I've met before and now the

 

focus of my attention.All of these components are in the same area and

 

suggest to me "power supply components".

My plan at the moment is to replace these capacitors in the hope that

 

the fault will disappear and to that end I now have the motherboard out

 

of the case.

 

My first problem concerns the values of these components because the

 

writing is very difficult to read (I have vision problems).

There are 2 values which appear to me to be ;

1. 16v 1500uF

2. 63v 3300uF

My concern is with the 63v which I am aware could be 6.3v. Is it likely

 

that pc makers would use a capacitor with such a high voltage rating?

 

My second problem is the logic of assuming that the fault lies with

 

these components, am I on the right track or am I potentially

 

disgracing the good name of the species?

 

The system specs are as follows.

American Megatrends

M825 on motherboard

AMD 2400 processor.

A crap video board.But good enough!

512 meg memory

Floppy drive.

dvd rewriter (sony)

cd drive.

First hard drive 160 Gb (maxtor)

Second drive 80 Gb (maxtor)

Operating system is Win XP pro sp3

 

This is a system built some 8 years ago so no manufacturer as

 

such.Other than me!

I looked for the capacitors online and found them at Farnell's site but

 

won't order them until I'm a bit more confident with the "plan of

 

action".

 

So if anyone could help me with this I would be very gratefull and of

 

course....virtual beers on me!!!

 

tt, ( Peter)

[Dalo Harkin]

You could replace the capacitors, but what if thats not the cause...bulging capacitors does not always mean they are the cause, yes bulging indicates an issue (but not uncommon especially in an 8yr old system) systems run for years even with bulging capacitors.

 

If you replace the capacitors and they turn out not to be the issue, then you are back at square one.

 

An 8yr old MOBO would cost £10-£20 or less from ebay so is it worth it, if it was an older high spec MOBO then yes replacement of the capacitors would make sense but I dont think it does on such an old system

[tellietubbie]

Thanks for your reply Dalo. I agree with what you say...I just try to make things last as long as possible and if replacing the caps does solve the issue then to me thats preferable to slinging it on a dump somewhere.

Farnell want £8 for the caps so there's little to lose by trying it.I'll post again once the machine is reassembled.

Thanks again for your comments.

 

tt

[Plastic Nev]

In short, I will agree with Dalo, however, there may well be more issues than just the capacitors. If one out of those already bulging has gone completely, and although you get correct readings from the PSU while not connected, there may be nothing when it is, (I have seen that myself) so be aware that the PSU may just have been damaged by a bad capacitor. The other worry is that the fault may have gone further and damaged other components on the mother board.

If you don't mind trying the replacement of those capacitors, and forget the cost if it proves to not cure things, then it may be worth that try.

Incidentally, the voltage specified will most likely be 6.3 volts and not 63v. A 3300uf capacitor at 63 volts would be huge, around two inch (50mm) long and a minimum of 3/4 inch (20mm) diameter, if not even bigger at a guess.

As A Ps, I just checked and I wasn't far wrong at 44mm long, 22mm dia.

Nev.