computer power supply round 2

[fkuk]

ok i found myself a new computer power supply


it has a dell logo on it
the connector is this one DELL ATX motherboard Power Supply pinout and wiring @ pinouts.ru

and i want to conferm on how to turn it on without a motherboard

do i connect pin11 GREY to ground and it should turn on

i want to know because i ruined my last power supply

 

[MrAl]

Hi,


Isnt it the green wire that gets connected to ground to turn it on? You can check on the web for wiring diagram for
the connector.

 

[fkuk]

there is no green wire on my power supply
and all the wires colours match up

i seem to have it working now but i want to confirm it
i have connected grey to ground
and organge to red
now i am getting 11.98V on yellow
and i am getting 5.13V on red
voltage readings are good

but i want to know that i have done it corectly

thanks

 

[ericgibbs]

there is no green wire on my power supply
and all the wires colours match up

i seem to have it working now but i want to confirm it
i have connected grey to ground
and organge to red
now i am getting 11.98V on yellow
and i am getting 5.13V on red
voltage readings are good

but i want to know that i have done it corectly

thanks

hi,
Have a look at this link:
Converting a PC Power Supply

 

[Thunderchild]

very interesting link eric never thought myself of bothering to put bannana socket on the case and make it a fully self contained unit

 

[fkuk]

are there simple ways to increasing the current out atm i have 3A on 12V is there a way to get higher current

i want to power a 75W 12V halogen bulb but that needs 6.25A is that too much to ask for
and also a 50W 12V halgen bulb needs 4.1A

the anoying thing is that at 5V the current out is 18A

 

[Thunderchild]

I think you may be asking for too much, older power supplies did not have very much power at 12 volts because 12 volts was used just to run motors like the HDD, it was only later that they decided to have on the motherboard voltage regulators that would take from the 12 v rail and convert to say 1.5 V for the proccessor

 

[MrAl]

Hi,


Yes i see now that that is an older power supply, and i believe connecting grey to ground is the right way to turn it on.
What i dont understand though is why you connected orange to red. The orange wire is an output wire isnt it? That tells the mobo that the power is working ok right? I dont think that should be connected to anything as that is an output right?

 

[Reloadron]

The following is from the ATX PSU design guide:

PWR_OK is a “power good” signal. It should be asserted high by the power supply to

indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the under-voltage

thresholds listed in Section 3.2.1 and that sufficient mains energy is stored by the converter

to guarantee continuous power operation within specification for at least the duration

specified in Section 3.2.11, “Voltage Hold-up Time.” Conversely, PWR_OK should be deasserted

to a low state when any of the +12 VDC, +5 VDC, or +3.3 VDC output voltages

falls below its under-voltage threshold, or when mains power has been removed for a time

sufficiently long such that power supply operation cannot be guaranteed beyond the powerdown

warning time. The electrical and timing characteristics of the PWR_OK signal are

given in Table 13 and in Figure 6.

Table 13. PWR_OK Signal Characteristics

Signal Type +5 V TTL compatible

Logic level low < 0.4 V while sinking 4 mA

Logic level high Between 2.4 V and 5 V output while sourcing 200 μA

High-state output impedance 1 kΩ from output to common

PWR_OK delay 100 ms < T3 < 500 ms

PWR_OK risetime T4 ≤ 10 ms

AC loss to PWR_OK hold-up time T5 ≥ 16 ms

Power-down warning T6 ≥ 1 ms

So yes it is actually an output from the PSU to the motherboard. This link is a somewhat illustrated what happens when we press the power button to start a home computer with a standard ATX form factor PSU. Also for anyone interested this link is a link to the PSU Design Guide ver. 2.01.

Ron