Problems withh a 250W power suply

[costel15]

My PC, a 900Mhz Duron on SIS MB, worked perfectly almost 2 years until last september when suddenly, when trying to read a CD it started to inexplicably plant. After using the back on/off button and power on the PC withh the front one again it worked prety good but more and more worse til it stoped to function after a short breath. The cycle was the same after a certain pause. I suspected the power suply so I took it of the case and I checked the final capacitors of the 5V and 12V lines. I fixed them more firmly with fludor but the function continued to be similar to the one described before. I want to repair it but I don't have a 250W power suply diagram or chart. Also any solution is welcomed.

[jabarnutcase]

Personally, the solution I would use is to try a brand spankin' shiny new Power Supply. :p
Not only does it sound like it's time, but it would be nice to have a little more power available too.

Even if you don't want to go nuts, a nice Antec 300W or 350W can be found for a pretty reasonable price. ( Especially since people are going for 450W, 550W or even higher these days).
The reason I use Antec as an example, is that you want to go with a quality Power supply.
Often the "Wattage rating" doesn't mean a thing other than an attempt to impress you. You want to pay close attention to the Power available on the individual voltage rails. Antec makes a good quality Power Supply.

If you really must tinker, you would want a schematic and the proper test equipment to repair that one. Keeping in mind of course that Capacitors can hold a healthy charge for quite some time.....

Go for the gusto and try a new Power Supply. :cool:

Oh! Almost forgot.....Welcome to the http://www.pcguide.com/ubb/pcgubb.gif Forums!!! ;)

[costel15]

Your suggestion is indeed a good solution but I'd be happy to fix it myself.

[jabarnutcase]

Well, the key here is: I want to repair it but I don't have a 250W power supply diagram or chart.

Just any old Schematic won't do. You would want the exact Schematic for that particular Power supply.
If somehow you knew for sure that bad capacitors were the problem, and could easily find exact replacements that would be one thing.

It seems however that you're not absolutely positive it's the Power Supply at all (or if it is, that the problem is with the Capacitors), so at least replacing the PSU would eliminate it as the problem.
As you probably know, there is a whole lot of other stuff in there too besides Capacitors. Including most likely a Bridge Rectifier, Resistors, Coils, etc. etc.(Well, you get the idea....a bunch of other "goodies").

Again, this is only my opinion. I actually used to tinker quite a bit myself (ever since I was a kid building "Heathkit" shortwave Radios).

HOWEVER, without the exact Schematic and all necessary test equipment, I would certainly take the easy way out in this case and buy a new one. (If you know the exact Model Number, you may be able to write the Manufacturer or find something on the web...maybe not)

Still, we're not talking refinancing the house here to buy a new one.. :p

Again, only my opinion.....others will be along to offer suggestions. ;)

[pentachris]

Aren't there coils inside PSU's that hold a significant amount of voltage even after being turned off and sitting idle for a long time (like monitors)?

[jabarnutcase]

Yes...(From above post):
Keeping in mind of course that Capacitors can hold a healthy charge for quite some time.....

Guess I should have said "unhealthy" charge though! :eek: :p

Another reason to not mess around and go for an upgrade instead (IMHO). ;)

[saphalline]

I have to wholeheartedly agree with the others here. Fixing a PSU is almost as useless as fixing a floppy drive. What do you save? Is the cost really worth it? In this case, I'd say no.

Think of the alternative. If you try and fix that old PSU, plug it in, and fry your whole system, are you prepared for that? I don't know about you, but I don't have $1500 laying around to replace my PC!

If you really must tinker, the cost will be more than a new PSU, unless you already have all the necessary equipment, like an ATX power tester, voltmeter, soldering iron, solder, solder remover, spare electronics parts, etc. I mean, really, did you know that a new 300W PSU is only about $30? Including shipping!?

[costel15]

Though, I know people who take the chance to fix a power supply. In fact mine is not wholy damaged, I think it's some lack of power somewhere inthere, but the guess where is imposible to one who doesn't know the schematic.