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Franc Zabkar

On Fri, 8 Aug 2008 22:52:43 GMT, put finger to keyboard
and composed:

I thought I had repaired this Dell W3000's power supply , but
after about 20-30 minutes the power light goes out (no video or audio)
and the power light comes back on (sound and video returns for a sec.).
IOW, the power goes off and then back on. Over and over again with a few
seconds in between.

All the voltages appear to be correct. I'm just not sure if it's the power
supply or
logic board. I replaced the bridge Rect.(it was shorted), 20N60 Transistor
(shorted), Controller IC (shorted). and a couple of
Schottky Diodes. This could be heat related.

Any help or direction on this would great!!!!

TIA

No specific help, but some general ideas ...

Assuming the Schottky diodes are on the secondary side, then it might
pay to see what's connected to those rails.

Otherwise, if you think the uP may be shutting down the supply, then
try to locate a PS_ON pin.

If it's a thermal problem, then try to narrow it down with some spray
freeze and a hair dryer.

As a matter of course I'd check the ESR of all the electrolytic caps.

What is the part number of the PWM controller IC? Perhaps its
datasheet has an application circuit.

- Franc Zabkar
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