psu doa?

  • Thread starter Thread starter legion
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legion

I finally got my cheap-o psu.
I pluged it in to two differend cords
it is the kind with the switch on the back
it should come on right? without beeing plugged into a board?
 
No. It will not run until it is plugged into the motherboard. There is a way
to make it run unconnected by running a jumper between 2 specific wires, but
why do that?
 
legion said:
I finally got my cheap-o psu.
I pluged it in to two differend cords
it is the kind with the switch on the back
it should come on right? without beeing plugged into a board?
Click to expand...

The rear switch will turn on only the +5V standby voltage on the
purple wire. For ATX power supplies to turn on completely, they
require a signal from the computer that shorts the green Power_On wire
(pin 14) to ground. You can do this with a paperclip between that
green wire and either black wire next to it, although a few supplies
also require a load on the +5V, between any red and black wires (use a
resistor rated at least 10 watts and ranging anywhere from 8-25 ohms).
With the supply running like that, its voltages can be measured with
a meter but may not be inaccurate.
 
thanks!
the POS CPU works great
quiet 4 inch fan first class iso-9001 components
honycomb rear plate for ventalation

powers up the board, the otherone must of crapped out during all of my
experimenting
 
legion said:
I finally got my cheap-o psu.
I pluged it in to two differend cords
it is the kind with the switch on the back
it should come on right? without beeing plugged into a board?
Click to expand...

No. If this is a standard ATX PSU and not an AT PSU (now largely
obsolete), the PSU needs a trigger from the mobo to turn it on. Until
that trigger is fed back from the motherboard, there will be only a
5-volt standby power going to the mobo. This 5V supply is a low-power
line and is NOT the same as the main 5V output.

A standard ATX PSU will have a bunch of wires going to a 20-pin
connector block arranged in two rows of 10. To turn this type of PSU
manually, identify pin #14 (green wire), short this pin to either of
the adjacent pins (black wire) with a short length of wire. It should
then turn on w/o being connected to the mobo.

However, certain makes of PSU need a minimum load to operate properly.
You can connect it to a floppy drive or a CD-ROM drive to this end.
I'd advise against using a hard disk for this purpose.
 
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