I have had a lookup about building a Bench supply from an old PC PSU. I read that for an ATX supply a load is usually required for the switched mode PSU to work, but this is not usually required for older AT supplies.
Anyway I have a PSU from an old Compaq Deskpro machine I would like to convert, it has a nice shaped case for a bench supply with a sort of stepped front where connectors can be placed. It appears to be an 'AT like' supply, with an external power switch, higher current/power +5V output than +12V and a -5V output, though the motherboard connectors are neither AT nor ATX standard, but that's Compaq for you. However the power switch isn't the standard AT version between supply and PSU but comes from the PSU circuit board with AC connected directly to the circuit board. I have connected 10Ω 10W resistors between both +12V and +5V and ground to give it a load in case it is needed however the PSU fails to spin up. The fan 'kicks' once and then no more.
The only wires currently connected are the +5V and +12V to Ground via the resistors.
Marked Output ratings, from the label, are :
OUTPUT:
244W MAX
+5V 32A +12V 6A -12V 0.9A -5V 0.2A
OR
+5V 15A +12V 6A -12V 0.9A -5V 0.2A +3.3V 25A
The wires on the circuit board that went to MB connectors are labeled as :
black ground
red +5v
orange +12v
blue -12v
yellow -5v ?
brown +3.3v
purple nic - led?
white/red hd - led?
white/orange pwr - led?
white fan sw
white/brown 3.3v S+
white/black 3.3v S-
As well as these there are the PSU fan, 110V/220V selector, AC power and the power switch conectors. Those marked 'led?' connect next to 3 small LEDs on the edge of the circuit board and look like they may be indicators as they poke through the side of the PSU case.
Does anyone have an idea what of the other wires may need connecting to where to get the PSU to fire up correctly ?
If there are no suggestions I'll just try a few and see what happens, since it's not of use now then there will be no loss if I blow it ...
Anyway I have a PSU from an old Compaq Deskpro machine I would like to convert, it has a nice shaped case for a bench supply with a sort of stepped front where connectors can be placed. It appears to be an 'AT like' supply, with an external power switch, higher current/power +5V output than +12V and a -5V output, though the motherboard connectors are neither AT nor ATX standard, but that's Compaq for you. However the power switch isn't the standard AT version between supply and PSU but comes from the PSU circuit board with AC connected directly to the circuit board. I have connected 10Ω 10W resistors between both +12V and +5V and ground to give it a load in case it is needed however the PSU fails to spin up. The fan 'kicks' once and then no more.
The only wires currently connected are the +5V and +12V to Ground via the resistors.
Marked Output ratings, from the label, are :
244W MAX
+5V 32A +12V 6A -12V 0.9A -5V 0.2A
OR
+5V 15A +12V 6A -12V 0.9A -5V 0.2A +3.3V 25A
The wires on the circuit board that went to MB connectors are labeled as :
black ground
red +5v
orange +12v
blue -12v
yellow -5v ?
brown +3.3v
purple nic - led?
white/red hd - led?
white/orange pwr - led?
white fan sw
white/brown 3.3v S+
white/black 3.3v S-
As well as these there are the PSU fan, 110V/220V selector, AC power and the power switch conectors. Those marked 'led?' connect next to 3 small LEDs on the edge of the circuit board and look like they may be indicators as they poke through the side of the PSU case.
Does anyone have an idea what of the other wires may need connecting to where to get the PSU to fire up correctly ?
If there are no suggestions I'll just try a few and see what happens, since it's not of use now then there will be no loss if I blow it ...