Re: Power supply build quality pictorial. part 2
It will do 300W. The limiting factor is always the efficiency (or lack thereof). 3.3V and 5V diodes can be left alone since those rails do not see much use in modern computers. Use at least 60A diode for 12V and it should be fine.
The reason why you see such a huge overrating of diodes in brand name PSUs is that the higher the current rating of the diode, the lower its voltage drop. Lower voltage drop, higher efficiency. And with heatsinks as flimsy as that, you'll want to squeeze as much efficiency out of it as you can, so overrate your output rectifiers a lot, and also swap the output inductor if you have a larger one in your junk box. Upgrading the primary transistors will do nothing if the secondary is inefficient, because these transistors do not burn out because of overcurrent, the reason is always thermal runaway. If you can find one that fits, replacing the primary heatsink with a larger one is going to do more good than replacing the transistors with higher rated ones.
The reason these pieces of junk blow up at 250-300W output is the very low efficiency due to inadequate output filtering, high voltage drop in output rectifiers and thin wiring in the output inductor. Improving the efficiency of the secondary side makes the stress on the primary lower for the same output power.
Solder in extra cables.
Originally posted by goodpsusearch
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The reason why you see such a huge overrating of diodes in brand name PSUs is that the higher the current rating of the diode, the lower its voltage drop. Lower voltage drop, higher efficiency. And with heatsinks as flimsy as that, you'll want to squeeze as much efficiency out of it as you can, so overrate your output rectifiers a lot, and also swap the output inductor if you have a larger one in your junk box. Upgrading the primary transistors will do nothing if the secondary is inefficient, because these transistors do not burn out because of overcurrent, the reason is always thermal runaway. If you can find one that fits, replacing the primary heatsink with a larger one is going to do more good than replacing the transistors with higher rated ones.
The reason these pieces of junk blow up at 250-300W output is the very low efficiency due to inadequate output filtering, high voltage drop in output rectifiers and thin wiring in the output inductor. Improving the efficiency of the secondary side makes the stress on the primary lower for the same output power.
Originally posted by goodpsusearch
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