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Powering on your cab without hitting the power button: the cap trick

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SirPeale:

--- Quote from: RandyT on December 11, 2008, 07:54:16 am ---Would you happen to know which boards don't work with the ATX power on jumper?  It seems odd to me that a piece of electronics could refuse to operate when given power, but nonetheless, I'd be interested in steering clear of them.  BTW, some power supplies need a hefty load on the 5v supply for them to turn on.  Just having a motherboard attached might not be enough.
--- End quote ---

I didn't make a list, no.


--- Quote ---*edit*  It seems like an item like this would be a good one to have on your store.  Just plug in the pre-attached connector and problem solved ;)


--- End quote ---

Unfortunately it's not as 'cut and dry' as that.  I've found that different motherboards require different caps.  I used an old dried-out cap on my boys cab for years that I salvaged from a cap kit I did.  I wish I'd had a meter to measure the ESR.  It finally stopped working after several years.  I replaced it with a 10uf 16V cap, and it doesn't work.  I would work with it to see what does, but I haven't had the time.
See above.

Zebidee:

--- Quote from: RandyT on December 11, 2008, 08:33:26 am ---
--- Quote from: Zebidee on December 11, 2008, 06:57:46 am ---A PC's Momentary on/off is actually controlled by the motherboard, which is why you need to use the cap trick on the power on/off switch on the mobo (look for the front panel header), not from ATX green pin 14.  I believe that this is the way that Peale has described the cap trick on his site.

--- End quote ---

Actually, you kind of have this a little twisted.  The "Momentary" is simply the nature of the switch.  When you press it, it completes a very low power circuit which, you guessed it, pulls the "power on" line low (same as connecting it to ground) while waiting, as it always does with power applied, for the ATX supply to raise the "power good" line to 5v.  At that time, it starts the system.  The mobo doesn't care if you release the switch because it is now holding the "power on" line low with it's own circuitry.  Your job is done ;)

RandyT

--- End quote ---

No, I haven't got it twisted at all.  I think that you have.

If you use pin 14, The PC will only stay on while the pin is shorted.    It is not a momentary response.  If you are using a momentary button, then the PC will shut itself down as soon as you take your finger off the button.  You could have a hard on/off switch, but that doesn't really seem like a good idea with a modern PC runnign WinXP, as they like to shut themselves down.

This is simply the technical specification, even if you happen to find an exception yourself somehow.    And to top it off, I have tried to do it before myself and had exactly the response I have described - the PC stays on only so long as you keep the button pressed (ie keep grounding pin 14).

RandyT:

--- Quote from: Zebidee on December 11, 2008, 04:13:11 pm ---If you use pin 14, The PC will only stay on while the pin is shorted.    It is not a momentary response.  If you are using a momentary button, then the PC will shut itself down as soon as you take your finger off the button.

--- End quote ---

Nobody has suggested using it like this.  I'm not exactly sure why you think they have.  It doesn't make much sense to argue about something that isn't really part of the discussion.


--- Quote --- You could have a hard on/off switch, but that doesn't really seem like a good idea with a modern PC runnign WinXP, as they like to shut themselves down.

--- End quote ---

Regardless of what you think seems like a good idea, it works, is part of the ATX specification and causes no ill effect.  If you are really worried about doing it this way, simply disable the power handling options in either the BIOS or in Windows.  Most will want to do this for a cabinet anyway.


--- Quote ---This is simply the technical specification, even if you happen to find an exception yourself somehow.    And to top it off, I have tried to do it before myself and had exactly the response I have described - the PC stays on only so long as you keep the button pressed (ie keep grounding pin 14).

--- End quote ---

I have deployed many a commercial kiosk in my past and this is what we did on every one of them.  You can infer that you don't think it works or isn't correct, but my experience has provided evidence to the contrary.   As for whether it stays on after removing the ground, of course it doesn't.  Nobody suggested using a switch here, rather you are supposed to jumper the wires.  The whole point is to eliminate the switch :).

RandyT

Zebidee:

--- Quote from: RandyT on December 12, 2008, 07:50:11 am ---
--- Quote from: Zebidee on December 11, 2008, 04:13:11 pm ---If you use pin 14, The PC will only stay on while the pin is shorted.    It is not a momentary response.  If you are using a momentary button, then the PC will shut itself down as soon as you take your finger off the button.

--- End quote ---

Nobody has suggested using it like this.  I'm not exactly sure why you think they have.  It doesn't make much sense to argue about something that isn't really part of the discussion.


--- Quote --- You could have a hard on/off switch, but that doesn't really seem like a good idea with a modern PC runnign WinXP, as they like to shut themselves down.

--- End quote ---

Regardless of what you think seems like a good idea, it works, is part of the ATX specification and causes no ill effect.  If you are really worried about doing it this way, simply disable the power handling options in either the BIOS or in Windows.  Most will want to do this for a cabinet anyway.


--- Quote ---This is simply the technical specification, even if you happen to find an exception yourself somehow.    And to top it off, I have tried to do it before myself and had exactly the response I have described - the PC stays on only so long as you keep the button pressed (ie keep grounding pin 14).

--- End quote ---

I have deployed many a commercial kiosk in my past and this is what we did on every one of them.  You can infer that you don't think it works or isn't correct, but my experience has provided evidence to the contrary.   As for whether it stays on after removing the ground, of course it doesn't.  Nobody suggested using a switch here, rather you are supposed to jumper the wires.  The whole point is to eliminate the switch :).

RandyT

--- End quote ---

I just deleted everything else I wrote in this post to say one thing to Randy - The whole point of this thread was to discuss the cap-trick (not wire-shorting), and that was what I was discussing with regard to pin 14.  If you want to talk about something else, then start a new thread.

I know what I am talking about Randy. I suspect that you do as well.  But attitude won't solve anything.  I'm bored with this discussion and want to move on now.

Thanks.

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