n Island, New York. >>> For some strange reason, you're trying to boot from the network, not >>> from internal disks.. >>> I don't have a second computer, so I can't check how one disabled that >>> function in the BIOS >> PXE boot code typically runs, if a disk cannot be found. >> >> On a good BIOS, you can go into the hardware setup, and >> disable the boot ROM for the NIC, and stop those messages >> from appearing. >> >> The "disk boot failure", means that none of the devices >> in the boot order, were located. >> >> Paul > > I have no choice but to use this system until I can get another. > > The drive is still holding, but the PC will sometimes freeze or crash > and restart. I then get this 9 out of 10 times: >
http://i290.photobucket.com/albums/ll257/Statenislander/Computer/AfterCrashA_zps2d57c187.jpg > > Though I got this once: >
http://i290.photobucket.com/albums/ll257/Statenislander/Computer/AfterCrashB_zps44114a74.jpg > > I attempted to test the power supply, but for
some really strange > reason I can't get it to turn on when it is disconnected from the > motherboard and drives. I shorted the green "Power-on" pin to the > ground next to it by sticking some 18g stranded wire into both, but it > still wouldn't turn on. > > Darren Harris > Staten Island, New York. Verify your pinout. Just in case the colors on the harness are wrong. (20 pin modern - page 30 - pin 14 is PS_ON#, COM on either side)
http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf (24 pin modern - page 37 - pin 16 is PS_ON#...)
http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf If a power supply "latches off" on a fault, you would need to flip the switch on the back to the off position, wait 30 seconds, then flip it on again. Then try holding PS_ON# to COM, for as long as you want the PSU to run. If the power supply is latching off, it may be "weak" and need replacement. If I was present in the room, I'd have my multimeter out by now, set
to 20V full scale, and would be doing a lap of the main connector pins while the computer is running. Just to see if the voltages are within 5% of nominal. Then, I'd repeat with Prime95 running, to add some electrical load. There are several ways to kill a hard drive. 1) The hard drive has devices across +5 to GND and +12 to GND, to absorb transients (such as disconnecting a drive "hot"). If the power supply goes to 7V and 15V perhaps, those components burn. Too much PSU voltage, will damage a drive. 2) The SATA and IDE, use relatively low voltages for operation. Sending a voltage down the line, outside the allowed range, burns the I/O. So those are ways the disk could get ruined. Using my multimeter, I'm effectively checking for (1). With (2), the motherboard I/O are likely to be ruined, so no further connected hard drives would ever be detected. And yet, if you connect new drives, they are present for a period of time. Thus, I suspect (1). The reason (2) is less common, is
the entire motherboard might be ruined by the root cause of such a thing, rather than just blowing out the disk I/O. If it was (2), maybe the motherboard would simply have stopped POSTing entirely. Test with another power supply, if you have any doubts. Check Newegg reviews, to find units with good reports. Paul
I know the pinouts are correct. I rechecked several times with the ITX motherboard pinouts in the manual and also online.
I'm not sure what "latches off" means, but there is no switch on the back of the power supply. (This is a mini-ITX PC which I've really only been using since January).
And I don't see a way to test the power supply with it connected to the motherboard. (And again, I cannot buy any new hardware).
I'll take a look at hooking up one of my regular size ATX power supplies to this system for a while to see if it experiences the same symptoms. But since the ITX motherboard has a 20 pin main connector, I'm not sure I can do that.
Thanks.
Darren Harris
Staten Island, New York.
There is information on connectors here.
http://www.playtool.com/pages/psuconnectors/connectors.html
You can plug a 24 pin supply, into a 20 pin motherboard, like this.
Pin 1 aligns with pin 1, and there will be four pins hanging off one
end. The plastic latch on the connector, will align with its mate
on the motherboard. This will not work, if there happens to be an
electrolytic capacitor on the right-hand end of the white connector
(which sometimes happens).
http://www.playtool.com/pages/psuconnectors/24in20.jpg
You can also plug a 20 into a 24. Again, pin 1 to pin 1,
latches mating. The 24 pin ends up with four pins unconnected,
but they are redundant pins. The motherboard still works.
Only if a couple 6600 video cards were installed, would
there be a problem with too much current flowing in the
single yellow wire. Your mini-ITX would not allow that
anyway (not enough expansion slots).
http://www.playtool.com/pages/psuconnectors/20in24.jpg
When I need to measure voltages on the connector (taking
last picture as a reference), if I look down into the
back of the power supply connector (black), I will see
exposed metal for each crimped pin. Those side-angle
photos don't show enough of the back of the connector,
to make that apparent. I shove the multimeter probe, into
the back of the PSU connector, to take measurements. I
sometimes use a needle probe (sewing needle with wire
wrapped around the outside to hold it in place), for
recessed measurements. So it is possible to get a
measurement off the thing.
*******
I purchased an extension cable at the computer store, like this.
http://www.playtool.com/pages/psuconnectors/20to24adapter.jpg
Those come in various combinations. 20 to 20. 24 to 20. The
20 to 20 (cost me $8.00), could be used to solve the
problem of a capacitor getting in the way of plugging a
24 PSU to a 20 motherboard. The nice cables, will be constructed
with proper wire colors, to hint at proper connection. But the
one I bought, they didn't bother with proper color coding. And
$8 was a bit much for such a thing. It should have been
cheaper than that.
You can also build your own cables. My one good electronics
store in town, used to stock all the parts. That's how I got
the connector bits, to build my own load box for PSU testing.
*******
A "latching" power supply, is one in which the voltage
regulator detects a current flow fault (short circuit),
and the regulator shuts off and "remembers" that a
fault has occurred. It does this, to prevent fire or
damage, and is appropriate for high power devices. It
takes electricity to do the "remembering", and completely
turning off the flow of power (unplug from wall if need be),
will reset the detection feature.
There were some other power devices, where "put put" mode
is used. The regulating device, retries about once a
second, and shuts off immediately if overcurrent is
detected again. Circuits that retry, are good for
situations where you know there may be a heavy load
at startup, which might trigger overcurrent, but you
are confident it will resolve itself. A circuit like
that, may detect just one overcurrent event at startup,
retry, and come all the way up. So that is the other
philosophy of design. That was popular with things
around the year 2000. If there is a real short
circuit, the physical location where the fault is
may get warm or hot, from the retries happening
once a second. With the power circuit that latches
off, things remain ice cold (safe).
*******
The pico supplies, use a DC-DC converter on a
circuit board, to convert voltage from a wall adapter,
into multiple DC voltages for a miniITX board. This could
be the style of power source you have for your mini-ITX.
These are available, up to about 120 watts. The one
pictured here is rated for 80 watts max.
http://static.mini-itx.com/store/images/1876-picopsu80.jpg
You power the input of a pico supply, with a wall adapter
like this one. This is rated 110 watts for example, enough
to run a pico 80. You are expected to read the voltage
rating of the two devices (input range), to make sure you're
mating "like with like".
http://www.mini-itx.com/store/images/psu.jpg
There are some pico supplies, intended for automotive
usage, with wide input range, and cutoff to prevent
total draining of the car battery.
Plenty of fun toys for mini-ITX users, assuming
the mini-ITX actually does something useful for them...
Paul
