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<div class="gmail_quote">On Fri, May 29, 2009 at 11:11 AM, Brian Wood <span dir="ltr"><<a href="mailto:beww@beww.org">beww@beww.org</a>></span> wrote:<br>
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<div class="im">On Friday 29 May 2009 09:40:21 Alan Marchiori wrote:<br>> Well, I swapped out the RAM, no change. Then I swapped the PSU and<br>> low and behold it has been stable ever since. I have been working<br>
> with PCs for a long time and have never seen a "bad" PSU where you<br>> could still boot the machine (usually it's just dead). It is a<br>> Seasonic PSU with a 5 year warranty but they say if the fan turns on<br>
> the PSU is not bad (and the fan does turn on). I guess it could have<br>> been a loose connection somewhere. I could swap it back and try to<br>> fiddle with it, but I'm just happy to have my myth box working again.<br>
<br></div>"If the fan turns on the PSU is not bad" is perfectly horrible advice. The fan<br>will turn with poorly-filtered DC power, incorrect voltage and a host of<br>other problems. DC motors are far less demanding in their power requirements<br>
than solid-state electronics.<br><br>I'd guess you have a filter capacitor that is breaking down shortly after<br>power is first applied, resulting in poorly-filtered power (an oscilloscope<br>would confirm this).<br>
<br>PSU problems that still permit the machine to boot up are really quite common,<br>though often mis-diagnosed. Often the entire machine is replaced and the<br>actual problem never discovered.<br><br>The "testers" that sell for under $20 are pretty much worthless, they merely<br>
indicate the presence of the various voltages, not the accuracy or quality of<br>the power produced. They also do not load the supply. They can reliably<br>diagnose only a total failure of one or more of the rails.<br><br>
I'm glad you're back in business. Upgrading is always nice, but only when it's<br>your idea.<br><font color="#888888"><br>--<br>beww<br><a href="mailto:beww@beww.org">beww@beww.org</a><br></font>
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<div><br>Hi Brian</div>
<div>I wonder, is there any good way to test a PSU without an oscilloscope?</div>
<div>I can vouch for the $20 tester not being that good.I had one that showed all voltages </div>
<div>were right (i.e. the LED's would lit up) nevertheless all the problems with the system </div>
<div>were solved after changing the PSU. go figure<br clear="all"></div>
<div></div><br>-- <br>------------------------------<br>/\_/\ <br>|O O| <a href="mailto:pepebuho@gmail.com">pepebuho@gmail.com</a><br>~~~~ Javier Perez<br>~~~~ While the night runs<br>~~~~ toward the day...<br> m m Pepebuho watches <br>
from his high perch. <br>