Re: PSU problems

w_tom <w_tom1@xxxxxxxxxxx> wrote in
news:435EDB69.22E18D3F@xxxxxxxxxxx:

....
>
> Why does the +5VSB not exist? Of course, first remove power
> cord from wall before breaking any connections. Then
> disconnect power supply from motherboard, restore AC power to
> supply, and again check for that +5VSB. If the +5 volts
> exists, then a short exists on motherboard. If +5 volts does
> not exist, then power supply or its power cord fuse (or a
> power supply switch if one exists) has failed.
>
....

> McSpreader wrote:
>> Ok, sounds a good methodical approach. So I decided to examine
>> some test cases, but got stuck at the first one. The test
>> scenario is: with mains power connected:
>>
>> 1) All pins on the 20-way connector read 0V.
>>
>> 2) Press the power-on button: makes no difference to readings.
>>
>> 3) Release the power-on button: makes no difference to
>> readings.
>>
>> Which component needs replacing?

I tried a few other test cases. In each one the voltage readings
from the 20-way connector alone are inconclusive. Which is not
surprising because the PSU and motherboard are mutually dependent.
Given an anomalous reading on the interface connector, it is
impossible to determine which party is the cause. To make progress
in determining the faulty component, you need to separate the two.

So I don't understand the value of your approach to diagnosis.
.

Loading