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Power Button Problems



 
 
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  #1  
Old July 30th 18, 11:53 PM posted to alt.comp.hardware.pc-homebuilt
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Posts: 53
Default Power Button Problems

I have an Optiplex 360 that I cannot turn on because of a faulty power button.

I have no idea how to repair this since I cannot get to the power button, which is sandwiched in between the plastic case and a metal cage.

There is a small circuit board which a 20 pin cable(XT029) is attached to and runs to the motherboard.

I cannot find the pinouts of the cable and was wondering if I can disconnect the cable from the front PCB, would there be a way to manipulate it to turn the PC on. (The audio in/out doesn't work on the front of the computer anyway, and I'd only be losing those USB ports).

Any ideas would be appreciated.

Darren Harris
Staten Island, New York.
  #3  
Old July 31st 18, 01:53 AM posted to alt.comp.hardware.pc-homebuilt
Bill[_39_]
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Posts: 38
Default Power Button Problems

mike wrote:
On 7/30/2018 3:53 PM, wrote:
I have an Optiplex 360 that I cannot turn on because of a
faulty power button.

I have no idea how to repair this since I cannot get to the
power button, which is sandwiched in between the plastic case
and a metal cage.

There is a small circuit board which a 20 pin cable(XT029) is
attached to and runs to the motherboard.

I cannot find the pinouts of the cable and was wondering if I
can disconnect the cable from the front PCB, would there be a
way to manipulate it to turn the PC on.


I would be thinking about cutting the cable and adding a switch
of my own. I think on main mainboards you can start the computer
by momentarily connecting two pins with a screwdriver.

(The audio in/out
doesn't work on the front of the computer anyway, and I'd only
be losing those USB ports).

Any ideas would be appreciated.

Darren Harris
Staten Island, New York.


optiplex-360_service manual_en-us.pdf

Indicates that there is one screw in an obvious, easily
reachable position, that releases the
board and you can remove it and trace the wire.

As I recall, the switch is on the board and there's a
plastic rod that actuates it.Â* Maybe that's busted.

I'm far to lazy to disassemble mine to pull it out.


  #4  
Old July 31st 18, 02:26 AM posted to alt.comp.hardware.pc-homebuilt
Paul[_28_]
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Posts: 1,467
Default Power Button Problems

wrote:
I have an Optiplex 360 that I cannot turn on because of a
faulty power button.

I have no idea how to repair this since I cannot get to the
power button, which is sandwiched in between the plastic case
and a metal cage.

There is a small circuit board which a 20 pin cable(XT029)
is attached to and runs to the motherboard.
I cannot find the pinouts of the cable and was wondering
if I can disconnect the cable from the front PCB, would
there be a way to manipulate it to turn the PC on. (The
audio in/out doesn't work on the front of the computer anyway,
and I'd only be losing those USB ports).

Any ideas would be appreciated.

Darren Harris
Staten Island, New York.


A front panel (logic level) switch can be
smashed in the ON position. I had one like
that once. The cheapest switch you can imagine,
where the little spring inside could no longer
"pop" the switch back out. I can't even remember
the brand of the case now. Come to think of it,
that might have been a machine at work.

The front switch is Normally Open (NO),
and is Momentary Contact. It makes a low-going
pulse. The switch pulls the logic signal to
Ground, causing a logic 0 pulse to be sent
to the motherboard. The motherboard "latches"
the pulse, and keeps the PSU energized via
the PS_ON# signal on the main ATX cable.

The switch signal *does not* go direct to the PSU.

When the switch is smashed in the ON position,
you might not be able to turn it on. Such a
switch must be disconnected from the motherboard
(somehow). The Power switch on the front, only
works if it can go through the entire pulse
process. Being stuck doesn't work to achieve
that end.

A switch which fails open, is less likely. A connection
could have fallen off the back of the switch.
Adding a Momentary Contact, NO switch to the
existing switch, helps in this case. Using
one of these buttons for example.

https://www.radioshack.com/products/pk2-spst-push-sw

And as a double treat, the terminals on the back
of that, demonstrate the wiring type that slides
onto the lug and grips it. In some cases, you could
slide the wires off the back of the switch. But if
the switch is affixed with solder to the PCB inside the
front panel of the machine (more likely to be how
yours is built), then it's not going to just
slide on outta there.

*******

Your computer has a "PSU BIST" switch somewhere.
BIST stands for Built In Self Test. And as a part
of testing the power supply, the switch may also
turn the computer on. Doing shutdown, would turn the
computer off again. The BIST switch may tide you
over, until another solution presents itself.
I've not read any accounts of using that, so
don't know what side effects it might have.

Paul
  #6  
Old July 31st 18, 05:53 AM posted to alt.comp.hardware.pc-homebuilt
mike
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Posts: 75
Default Power Button Problems

On 7/30/2018 6:34 PM, GlowingBlueMist wrote:
On 7/30/2018 5:53 PM, wrote:
I have an Optiplex 360 that I cannot turn on because of a faulty power
button.

I have no idea how to repair this since I cannot get to the power
button, which is sandwiched in between the plastic case and a metal cage.

There is a small circuit board which a 20 pin cable(XT029) is attached
to and runs to the motherboard.

I cannot find the pinouts of the cable and was wondering if I can
disconnect the cable from the front PCB, would there be a way to
manipulate it to turn the PC on. (The audio in/out doesn't work on the
front of the computer anyway, and I'd only be losing those USB ports).

Any ideas would be appreciated.

Darren Harris
Staten Island, New York.

Yes you can unplug the two wires from the motherboard that connect to
the switch. You could wire up a replacement from any switch that is
normally open, like a doorbell button.

To test the switch connections on the motherboard first unplug the power
switch connector and then momentarily short the two pins together with a
screw driver. The motherboard should then power on normally if the
switch or wires to the switch is all that is bad.

IN the O360, there are several connectors on the board with the power
switch.
There's a ribbon cable about the size of a floppy cable that connects
to the motherboard.

Can't do what you suggest without knowing the pinout of that cable...
which could be easily determined by removing the one screw that
attaches the board to the chassis.

The actual switch is some distance from the button and actuated
by a rather flimsy plastic linkage.

FWIW, the 360 power switch makes a rather loud "click" when you activate it.
Absent that click might indicate a stuck switch or broken plastic actuator.

I unscrewed the board in a Optiplex 320, same board, but I couldn't
see how the power switch actuator attached without removing the floppy.
I gave up.
  #7  
Old July 31st 18, 09:35 AM posted to alt.comp.hardware.pc-homebuilt
Paul[_28_]
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Posts: 1,467
Default Power Button Problems

mike wrote:
On 7/30/2018 6:34 PM, GlowingBlueMist wrote:
On 7/30/2018 5:53 PM, wrote:
I have an Optiplex 360 that I cannot turn on because of a faulty power
button.

I have no idea how to repair this since I cannot get to the power
button, which is sandwiched in between the plastic case and a metal
cage.

There is a small circuit board which a 20 pin cable(XT029) is attached
to and runs to the motherboard.

I cannot find the pinouts of the cable and was wondering if I can
disconnect the cable from the front PCB, would there be a way to
manipulate it to turn the PC on. (The audio in/out doesn't work on the
front of the computer anyway, and I'd only be losing those USB ports).

Any ideas would be appreciated.

Darren Harris
Staten Island, New York.

Yes you can unplug the two wires from the motherboard that connect to
the switch. You could wire up a replacement from any switch that is
normally open, like a doorbell button.

To test the switch connections on the motherboard first unplug the power
switch connector and then momentarily short the two pins together with a
screw driver. The motherboard should then power on normally if the
switch or wires to the switch is all that is bad.

IN the O360, there are several connectors on the board with the power
switch.
There's a ribbon cable about the size of a floppy cable that connects
to the motherboard.

Can't do what you suggest without knowing the pinout of that cable...
which could be easily determined by removing the one screw that
attaches the board to the chassis.

The actual switch is some distance from the button and actuated
by a rather flimsy plastic linkage.

FWIW, the 360 power switch makes a rather loud "click" when you activate
it.
Absent that click might indicate a stuck switch or broken plastic actuator.

I unscrewed the board in a Optiplex 320, same board, but I couldn't
see how the power switch actuator attached without removing the floppy.
I gave up.


The power button seems to be below the front I/O assembly.
Must be hard to get leverage from that far away.
(PDF page 82). I can see the one screw you're talking about.

https://downloads.dell.com/manuals/a...nual_en-us.pdf

Paul
  #9  
Old August 1st 18, 12:19 AM posted to alt.comp.hardware.pc-homebuilt
Flasherly[_2_]
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Posts: 2,407
Default Power Button Problems

On Mon, 30 Jul 2018 15:53:54 -0700 (PDT),
wrote:

There is a small circuit board which a 20 pin cable(XT029) is attached
to and runs to the motherboard.

I cannot find the pinouts of the cable and was wondering if I can
disconnect the cable from the front PCB, would there be a way to
manipulate it to turn the PC on. (The audio in/out doesn't work on the
front of the computer anyway, and I'd only be losing those USB ports).

-
The printed circuit board is common to cases, intended to electrically
tie, between the outside case controls and connections, to the cable
for the MB to receive those signals.

I would not disassemble the circuit board or the cable leads off that
board. You've a bad PS switch that functions as a momentary
electrical short, when pressed in, which in turn tells the MB to power
up, or down, the computer. It's otherwise in an open condition.

There are two pins on the MB that receive that signal and effectively
are then shorted together whenever the Power Switch is pressed.

You need find them. It's called the MB's case "jumper block" and the
individual pin-pairings should be so labeled. It'll take a bright
flashlight and magnifying glass to read them, as well as a steady hand
or slim needle-nose pliers to mate the case switch wire and female
connectionsto the MB male pins. Carefully look over the MB block
label for the correct pin pairings. Polarity is less important and
can usually can reversed without damage if actually called for.

You'll need a replacement switch. Most anything will work as it's a
continuity or logical condition that only functions when those two
pins are briefly shorted together. It's also a spring-loaded switch
to effect that end. You may get by with a flip of another type of
switch design, be it a quick on/off on your part from toggle or flip
switch. I've never tried it. I've pulled out that stuff from
computer cases which were updated, and have the spares. A PWR SW is
the functionally and mechanically the same as a RESET SW.

I've been in some "brandname" name computers put together exactly like
they're in their own little jigsaw puzzle. You punch, drill, a pin
hole, or thread the wires and replacement switch and let it dangle.
Not pretty but a definite argument for buying discrete parts and
assembling by standards. And, yeah, I've done it before - dangled out
my own when the PWR went flaky.
 




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