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Old 05-11-2007, 10:31 AM   #1 (permalink)
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Join Date: May 2007
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Default 7 VSB from power supply??

Computer won't turn on. When I push the switch, absolutely nothing happens. Here's what I've looked at so far:

When plugged in, the green led on the motherboard lights up, the motherboard has around 3 volts at the switch pin, the switch tests out ok,(shorting between the switch pins does nothing).

Checking the voltage at the 20 pin connector from the power supply yields the following: 2.4V at the PS_On green wire and 6.5 to 7 Volts at the VSB purple wire. VSB is suppose to be 5V from what I can tell. Is 7 V (or that it's voltage varies between 6.5 and 7) indicative of a PSU problem? Would it hurt the motherboard?

After jumping the PS_On wire to ground the power supply fan comes on and I get voltage that appear to be ok on all the other pins (as well as on the other connectors) 4.9V on red, pink and grey, 3.3V on Orange, 11.6V on yellow, -11.8V on blue and -5V on white.

Does this look like a power supply issue? Any advice on what to do next would be appreciated?

Computer is an emachine T2885 with a Bestec ATX-250-12E Rev P7 power supply, D845EPI/D845GVSR Intel motherboard and Pentium 4.

GregJ is offline  
Old 05-14-2007, 10:36 AM   #2 (permalink)
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Join Date: May 2007
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Default Re: 7 VSB from power supply??

Does anyone here know if a standby voltage of 6.5 to 7 Volts is indicative of a bad power supply?


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