PSU high voltage

Neodogg

Neodogg

Dogg-Father,
20 Year Member
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Nov 27, 2002
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5,606
So...my SFX stopped working and I opened it up and found a blown fuse. I've replaced it now but I tested the PSU and it seems to be a bit higher than the rated 9V. Does this mean there are bad caps?

klZX6ha.jpg



puloV80.jpg
 
titchgamer

titchgamer

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Neodogg said:
So...my SFX stopped working and I opened it up and found a blown fuse. I've replaced it now but I tested the PSU and it seems to be a bit higher than the rated 9V. Does this mean there are bad caps?

klZX6ha.jpg



puloV80.jpg
Click to expand...

The higher voltage wont blow the fuse (Thats done by higher current), But its a sign that there is a fault somewhere.
Could be caps or a regulator or ?????

Prob best just to buy a new PSU if its for a SFC and hope its not done any further damage to the console.
 
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shadowkn55

shadowkn55

Genbu's Turtle Keeper
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Dec 9, 2006
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wyo said:
What is a SFX?
Click to expand...

Super Grafx?

Those old "9V" power supplies don't push out 9V unless it's under load and even then it still hovers closer to 12V. The internal 5V regulator cuts it down to the proper voltage to run the system anyway. If you have the know how, recapping a psu isn't a bad idea either.
 
X

xwred5

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Mar 17, 2018
Posts
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For all unregulated power supplies, the output voltage will be higher at no load (disconnected) and will drop down lower at load. The 7805 Ldo will take up to 35v dropping it to 5V regulated to be used by the system.

15v seems on the high end, but probably okay.

Edit Oh since you are using a 100v linear transformer on a 115-125v input, the output will be 15-25% higher than when used in Japan. Which is why it seems so high.
 
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