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BrianG
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01.16.2008, 10:48 AM

OK, you have to make sure you are choosing the wattage correctly. The wattage rating advertised on the PS is for all the voltage rails combined. So, your 400w is split between the 12v, 3.3v, and 5v. This is why I have the table of currents listed for different voltages.

Also, it is not uncommon for the 12v line to dip like that under load. You can try loading the 3.3v and/or 5v line with a low resistance. That will help the regulator circuit to make the 12v line more stable.

There might also be a small PCB mounted potentiometer to allow you to tweak the voltage a tad. Some have this, some don't. Just look around inside and if you see one, make small adjustments while watching the voltage output. If nothing changes, return it to default because it's probably being used for something else (like switching frequency or something). Since the PS has to be open and turned on to do this, be CAREFUL not to shock yourself! Many times, the heatsink is floating at ~180v DC!
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sleebus.jones
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01.16.2008, 11:18 AM

Quote:
Originally Posted by BrianG View Post
OK, you have to make sure you are choosing the wattage correctly. The wattage rating advertised on the PS is for all the voltage rails combined. So, your 400w is split between the 12v, 3.3v, and 5v. This is why I have the table of currents listed for different voltages.

Also, it is not uncommon for the 12v line to dip like that under load. You can try loading the 3.3v and/or 5v line with a low resistance. That will help the regulator circuit to make the 12v line more stable.
Ah ahh ahhhh. Now I see. The 281w is for the 12v line only. Ok, that makes more sense. I believe the sticker on mine says the 12v is rated for 20A or close, which comes out to 240w. So yeah, 280w would probably work perfect.

I've got a 2 ohm sandbar (two 1 ohm resistors in series) on the 5v line to help pull the 12v side up currently. I don't really anticipate having to charge harder than that (I'm 0.6A short of the limit of the charger as is!) but I was hoping with that PSU that I wouldn't get that much of a dip...although this is the first charger that has made the wires going to the charger get warm!

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