computer power supply..

  • Thread starter Thread starter larya
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larya

Greetings...
I have taken the power supply out of a computer...
Power supply model number.. IBP-38A
Does anyone know how to start it...
The computer's on / off switch was / is on the front panel and the
connecting wire goes to the mother board... I still have the mother
board and have considered doing a board trace to track the wire to the
power supply....
However to save me some time would anyone know were the start circuit
is?..
Larry ve3fxq
 
Greetings...
I have taken the power supply out of a computer...
Power supply model number.. IBP-38A
Does anyone know how to start it...
The computer's on / off switch was / is on the front panel and the
connecting wire goes to the mother board... I still have the mother
board and have considered doing a board trace to track the wire to the
power supply....
However to save me some time would anyone know were the start circuit
is?..
Larry ve3fxq
Click to expand...
You have to loop back the "power good" wire on the 20/24pin motherboard
connector.

As it's a switch mode PSU, it'll also need a load on it as well.
 
larya said:
Greetings...
I have taken the power supply out of a computer...
Power supply model number.. IBP-38A
Does anyone know how to start it...
The computer's on / off switch was / is on the front panel and the
connecting wire goes to the mother board... I still have the mother
board and have considered doing a board trace to track the wire to the
power supply....
However to save me some time would anyone know were the start circuit
is?..
Larry ve3fxq
Click to expand...

The following link will show you how to get an ATX style power supply to
start but keep in mind that without a proper load, as in a motherboard or a
power supply tester with built in dummy load what you see with meter is not
necesarily valid. You may see voltages exactly to specs with no load but
plug it into something and then the voltages can vary widely depending on
what may be wrong with the power supply.
http://www.duxcw.com/faq/ps/ps4.htm
 
larya said:
Greetings...
I have taken the power supply out of a computer...
Power supply model number.. IBP-38A
Does anyone know how to start it...
The computer's on / off switch was / is on the front panel and the
connecting wire goes to the mother board... I still have the mother
board and have considered doing a board trace to track the wire to the
power supply....
However to save me some time would anyone know were the start circuit
is?..
Larry ve3fxq
Click to expand...

The front switch doesn't feed the power supply directly. The
signal is conditioned by motherboard logic. One of the necessary
functions carried out by the logic, is a four second delay before
shutting off the computer (to prevent accidents). The four second
delay is context sensitive as well, so the conditioning of the
front switch contact closure, depends on whether you're in
the BIOS or the OS etc.

X-------------- Motherboard ------ PS_ON# --------- ATX PSU
Logic
Front Chip
Switch
(Momentary) (latches signal)

The PS_ON# signal controls the soft switching of an ATX
power supply. That is a logic signal on the main cable.
The "#" in the signal name, means the signal is active low.
You ground the PS_ON# signal, to turn on the supply. "Conor"
and "GlowingBlueMist" have already suggested connecting PS_ON#
to an adjacent COM (ground) pin, to turn on the supply and make
the fan spin.

The 20 and 24 pin power connectors have similar pinout. The 24
pin connector is just a 20 pin, with four redundant pins added
to the end of it.

You can see how a 20 pin, is a subset of a 24 pin, here.

http://www.playtool.com/pages/psuconnectors/20in24.jpg

There are pinout tables available in the article as well,
so you can compare a 24 pin to a 20 pin.

http://www.playtool.com/pages/psuconnectors/connectors.html

Paul
 
Greetings...
I have taken the power supply out of a computer...
Power supply model number.. IBP-38A
Does anyone know how to start it...
The computer's on / off switch was / is on the front panel and the
connecting wire goes to the mother board... I still have the mother
board and have considered doing a board trace to track the wire to the
power supply....
However to save me some time would anyone know were the start circuit
is?..
Larry ve3fxq
Click to expand...

MB and tracking power traces? Good luck with a razor and microscope,
traces are epoxied within six layers down into MBs.

Power supplies work off a PWR-GOOD strobe. Combination of RESET and
PWR-ON - two two-way connectors on the MB jumper for the case setup.
You can also "start" a fuel injector with the right voltage and bench/
test setup, although not much point unless there's a known condition,
localized and within means of disassembly or cleaning.

What saves lots of time is simply having a PS in reserve. Open the
case, balance the new PS conveniently where there's no sparks, and
plug it in ontop the old one. Amazing what an excellent quality PS
does not reveal, placed beside all kinds of problems being produced by
a crap PS headed south.
 
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