ATX PSU - help wiring

[whiz115]

Hi!

recently i bought a new power supply for my PC...unfortunately i can't connect the front LCD panel of my computer case because the old PSU had
a small connector comming out and the new one is not designed to have one.

The connector has 3 wires... i measured the voltages comming out from and i'm getting 5V

BLACK 5V- (ground)
RED 5V+
PURPLE 5V+ (5V+ standby)


these wires are connected to the correspoding ones of the ATX connector,
and i don't understand why it uses 3 wires and why it take the 5V+ from the purple wire of the ATX connector, i'm not willing to open the PSU so i can connect the way it was in the old PSU... can somebody help me so i don't mess anything?

 

[OutToLunch]

The LCD panel was likely active or could be activated when in standby, so it would require 5VSBY. I don't see any reason to crack open the PSU. Just open the insulation on the corresponding wires in the main 20 pin harness, solder the wires together then tape them up.

 

[whiz115]

when i'm saying that i don't want to mess anything it's mostly about the guarantee of the PSU.

what if i just give it 5V+ and ground? i'm wondering if everything is going to
be fine...

 

[Sceadwian]

Seems odd if black is -5V. That means it needs a 10 volt supply. So supplying it +5V and ground (true 0) will either ruin the module or it just won't function. The LCD module isn't going to be drawing a lot of current so you should be able to get away using something like a header connector, or something thinner, like a trimmed needle/reem, to squeeze into the top of the 20 pin connector on the right voltage without hurting wiring, a needle/ream used to just wedge into the top of the connector a little for good physical contact should work fine and not disrupt anything, trim or shrinkwrap any extra wire/reap sticking out and make sure it's seated solidly and you should be fine. This is one thing Dremel tools are great for, mount a standard male .1" square header peg as if it were a bit and then use a grinding stone as if it were a micro lathe to give you a fine point, and then dull the point just a little so you don't kill anyone =)

 

[whiz115]

@sceadwian i did a small typo it's not 5V- it's ground! i'm sorry.

 

[Sceadwian]

Then skip the standby, it should work unless the LCD has controls which lose memory on power failure. This is probably not a good idea, but I think most USB power buses are still active in standby so you could try to steal a +5V standby from a free internal USB connection.

 

[whiz115]

sceadwian i was thinking that if it doesn't hurt not to give it the 5V+ standby voltage then i should steal some power from one of the molex connectors of the psu... somewhere i got a male molex and maybe i can cut the wires and connect the body with the wires of the other connector going to the LCD panel... what do you think?

 

[Sceadwian]

Sure, though whatever function the LCD serves will be reset every time the system goes into a power down mode.