need help with computer powersupply

[Walter Hofmann]

Hi all,
I need some help , I took the powersupply out of a old compaq computer and if I push the power btton it just starts for a split second and nothing.
can anybody help me out what is wrong.
thanks
greetings
walt

[gyulasun]

Hi Walter,

If your PC supply is ATX type, meaning the soft switch on/off is controlled from the motherboard, then you can find a green cable (Pin4) between two black cables on the 20 pin connector. If this is so, then you have to connect the green to any of the black pins neighboring this Pin4, being the black pins the (common negative) ground.
Simply close Pin4 to Pin5 or to Pin3 with a piece of bare wire and switch on the supply.

If the PC supply is not ATX type then probably it is faulty. there are some good info on PC supplies here: http://en.wikipedia.org/wiki/Modular_power_supply
and also see the External links at the bottom of that page.

Gyula

[hartiberlin]

Hi Walter,
you need to apply a load to the +5Volts line and probably
also to the +12 Volts line,
otherwise the power supply will switch itsself off,due to protection
circuits inside the power supply.

APCpower supply always want to see a load at least at the 5 Volts output.
So try to connect a 100 Ohm resistor  ( at least 0.25 Watts type or better 1 Watt type)
there to ground and try again.

Also there is sometimes additional sensing output lines in newer motherboard
designs, when I remember correctly...
This is an additional cable going to the motherboard andmust be set
to 0 Volts or + 5 Volts, so the motherboard tells the power supply, if
it should deliver power to it...

[Walter Hofmann]

Hi gyula and stefan,
thanks for the help I will try it.
greetings
walt

Hi Walter,
you need to apply a load to the +5Volts line and probably
also to the +12 Volts line,
otherwise the power supply will switch itsself off,due to protection
circuits inside the power supply.

APCpower supply always want to see a load at least at the 5 Volts output.
So try to connect a 100 Ohm resistor  ( at least 0.25 Watts type or better 1 Watt type)
there to ground and try again.

Also there is sometimes additional sensing output lines in newer motherboard
designs, when I remember correctly...
This is an additional cable going to the motherboard andmust be set
to 0 Volts or + 5 Volts, so the motherboard tells the power supply, if
it should deliver power to it...

[Walter Hofmann]

Hi guys
I try your advice but nether one did work I dont have a green wire and ataching a resistor 100 OHm to the 5V or 12V did not help ether.
the unit works because I did put it back to the rest computer and it workt fine.
I took a picture maybe someone can help me there.
thanks
walt

Hi gyula and stefan,
thanks for the help I will try it.
greetings
walt

Hi Walter,
you need to apply a load to the +5Volts line and probably
also to the +12 Volts line,
otherwise the power supply will switch itsself off,due to protection
circuits inside the power supply.

APCpower supply always want to see a load at least at the 5 Volts output.
So try to connect a 100 Ohm resistor  ( at least 0.25 Watts type or better 1 Watt type)
there to ground and try again.

Also there is sometimes additional sensing output lines in newer motherboard
designs, when I remember correctly...
This is an additional cable going to the motherboard andmust be set
to 0 Volts or + 5 Volts, so the motherboard tells the power supply, if
it should deliver power to it...