I assemble a new computer but won't powerup

[Efandin]

Help! I assemble an Antec Sonata case with 380W PS, ECS 648FX-A
Motherboard & INTEL 2.8 GHZ/ 800FSB Processor, 256MB DDR Memory,
Floppy, CD and 160G WDC Harddisk etc. It didn't power up not even the
fan can turn. What Wrong? The power source (cord) was good, Red Recess
reading was 115V, main switch was on "I". I used a meter to mesure the
connectors and there was no voltage reading. The motherboad, case, PS,
processor, Memory, Hard drive are new? Can it be a bad power supply?

 

[Rocky]

Help! I assemble an Antec Sonata case with 380W PS, ECS 648FX-A
Motherboard & INTEL 2.8 GHZ/ 800FSB Processor, 256MB DDR Memory,
Floppy, CD and 160G WDC Harddisk etc. It didn't power up not even the
fan can turn. What Wrong? The power source (cord) was good, Red Recess
reading was 115V, main switch was on "I". I used a meter to mesure the
connectors and there was no voltage reading. The motherboad, case, PS,
processor, Memory, Hard drive are new? Can it be a bad power supply?

Did you check the cable from the motherboard to the power button on
the front of the case? Without the power good signal from the
motherboard, the psu will never start.

see also my previous reply to another subject.

Rocky

 

[Mark D. Zacharias]

This happened to me recently. The front LED connection was wrong. Cost me
80.00 to find out.

:-(


Mark Z.

 

[Alan Harriman]

Help! I assemble an Antec Sonata case with 380W PS, ECS 648FX-A
Motherboard & INTEL 2.8 GHZ/ 800FSB Processor, 256MB DDR Memory,
Floppy, CD and 160G WDC Harddisk etc. It didn't power up not even the
fan can turn. What Wrong? The power source (cord) was good, Red Recess
reading was 115V, main switch was on "I". I used a meter to mesure the
connectors and there was no voltage reading. The motherboad, case, PS,
processor, Memory, Hard drive are new? Can it be a bad power supply?

Make sure the Cmos jumper is not in the reset position.

Alan Harriman

 

[BOB URZ]

This happened to me recently. The front LED connection was wrong. Cost me
80.00 to find out.

:-(

Mark Z.

Can you explain what you did? Backward or on the wrong pins?

Recently, i have been working on a Compaq with a SD-11 motherboard.
It would not turn on and boot either. I thought the MB was a goner.
I took out the CMOS battery for a minute, put it back it and then it would
turn on. Not quite sure why, but it did.

Bob

 

[James Sweet]

Help! I assemble an Antec Sonata case with 380W PS, ECS 648FX-A
Motherboard & INTEL 2.8 GHZ/ 800FSB Processor, 256MB DDR Memory,
Floppy, CD and 160G WDC Harddisk etc. It didn't power up not even the
fan can turn. What Wrong? The power source (cord) was good, Red Recess
reading was 115V, main switch was on "I". I used a meter to mesure the
connectors and there was no voltage reading. The motherboad, case, PS,
processor, Memory, Hard drive are new? Can it be a bad power supply?

Are all the fans connected correctly? Some boards won't power up if they
don't detect an RPM signal from the cpu fan.

 

[ToasterKing]

Assuming it's an ATX power supply and matches the color-coding
standard, you can short the green wire to ground (one of the black
wires) with a paper clip or other conductor, and the power supply
should power on if it's working, and so also should your computer.
Doing this bypasses the power management circuitry on the motherboard
and completes the circuit to the PSU's sensory pin as if the
motherboard had actually signalled the PSU to power up.

Also check to make sure your motherboard isn't shorting to the case!
Make sure all the standoffs between the case and board are installed
correctly, and that you don't have any extra metal standoffs that could
be touching the board in any place other than a mounting hole. This
can be an expensive mistake!

TK

 

[King David]

I had the same thing happen to me a couple of weeks ago.
A pc I use everyday would not do anything after using it the night before.
I took the power supply out and banged on it while I pressed the power
button.
It turned on for only one second which let me know that the power supply was
bad.
Replace it and everything is fine.
So Yes, it could be the power supply or it's not hooked up correctly.

 

[Daniel L. Belton]

Assuming it's an ATX power supply and matches the color-coding
standard, you can short the green wire to ground (one of the black
wires) with a paper clip or other conductor, and the power supply
should power on if it's working, and so also should your computer.
Doing this bypasses the power management circuitry on the motherboard
and completes the circuit to the PSU's sensory pin as if the
motherboard had actually signalled the PSU to power up.

You really shouldn't try that with the power supply plugged into the
motherboard.... If the motherboard isn't signaling the PS to power up,
then you could burn something up if you force it to. The motherboard
does certain tests, and if those don't check out, it won't signal the PS
to power up. Like... if the MB is grounded at some point it's not
supposed to be.. or a hard drive isn't properly connected, or your
memory isn't installed right... any number of things... bypassing this
feature and forcing the power to come on can and probably will blow
something.

Also check to make sure your motherboard isn't shorting to the case!
Make sure all the standoffs between the case and board are installed
correctly, and that you don't have any extra metal standoffs that could
be touching the board in any place other than a mounting hole. This
can be an expensive mistake!

TK

Should have told him that before forcing the power supply to come on!

 

[Efandin]

You really shouldn't try that with the power supply plugged into the
motherboard.... If the motherboard isn't signaling the PS to power up,
then you could burn something up if you force it to. The motherboard
does certain tests, and if those don't check out, it won't signal the PS
to power up. Like... if the MB is grounded at some point it's not
supposed to be.. or a hard drive isn't properly connected, or your
memory isn't installed right... any number of things... bypassing this
feature and forcing the power to come on can and probably will blow
something.


Should have told him that before forcing the power supply to come on!

Gentlemen, Thanks for all the comment. Just wonder those Brass
standoffs, screws and the silever color coated holes on the
motherboard made the MB grounded to the case? If so are they
considered short? Is devices like CD Rom if not properly connected
affects it to boot or just unable to detect the device? One important
question is that my 160 Gig WDC Harddrive came with a PCI Card and I
was told (manual)to use it. The PCI card has two extra IDE connectors
on top and I was told to connect the Hard Drive to Primary IDE
connector on it instead of the primary IDE connectors on the
Motherboard. My CD Rom was connected to the secondary IDE connectors
on the MB. This mean I have a total of four IDE connectors two on PCI
CARD (primary used) and two on MB (secondary used). Does this sound
right?

 

[Mark D. Zacharias]

Wrong pins entirely, a mistake prompted by a VERY easy-to-misunderstand set
of instructions from Gigabyte.
I checked and re-checked my connections, but in the end I had to take it to
the place I bought it from, and they figured it out quickly enough - at
their regular shop rates, that is. Felt like an idiot but it let me get on
with the business of building that computer.

Mark Z.

 

[JW]

Assuming it's an ATX power supply and matches the color-coding
standard, you can short the green wire to ground (one of the black
wires) with a paper clip or other conductor, and the power supply
should power on if it's working, and so also should your computer.

Most motherboards will power up, however, I have seen more than one
exception to that. IIRC, one of the motherboards that wouldn't work was
a Tyan, but I forget which model # it was.

 

[Daniel L. Belton]

Wrong pins entirely, a mistake prompted by a VERY easy-to-misunderstand set
of instructions from Gigabyte.
I checked and re-checked my connections, but in the end I had to take it to
the place I bought it from, and they figured it out quickly enough - at
their regular shop rates, that is. Felt like an idiot but it let me get on
with the business of building that computer.

Mark Z.

I got a motherboard a few years ago that was marked totally wrong as to
where the connections were. The manual was marked correctly, though...

Usually the manual is wrong and th markings on the board are right...
Oh well, live and learn

Glad you got it working!!

 

[Chaos Master]

BOB URZ said those words of wisdom from the arcane mages in
sci.electronics.repair:

Recently, i have been working on a Compaq with a SD-11 motherboard.
It would not turn on and boot either. I thought the MB was a goner.
I took out the CMOS battery for a minute, put it back it and then it would
turn on. Not quite sure why, but it did.

Bad CMOS data may cause this in some computers.

 

[jh40]

WRT the brass standoffs - I can't offer much help. Boards I am familiar
with have those holes at power supply common. Some I've seen are
neutral. Just to be safe, I'd use the plastic standoffs.
WRT the WD HD, is there another part of the story your not telling us?
Like perhaps the drive has a SATA interface? With that brand and
current vintage of the MB, it should be able to handle the drive via
the MB IDE connections directly...OR, is this maybe a SCSI drive???
Just out of curiosity, WHY were you told to use it?

In general, I've haven't seen the case where a bus device such as a
CD-ROM would inhibit the powersupply. It might keep it from booting,
but not powering up.

I would take the minimalist approach in troubling shooting
this...remove( take out the power connector and the ribbon cable) the
HD, CD-ROM, DVD, etc, all cards except the video card, keep in the FDD,
disconnect all external devices except the mouse & kbd. Double check
all the connections, especially from the board to the on/off switch,
disconnect all the LEDs. Make sure the case switches work correctly.
Try to verify that your MB manual is valid for the MB you have...i.e.
approximate rev level. If it comes alive, try and boot from a floppy...
Watch where you poke. When the AC line cord is plugged in, and the
computer is OFF, there is still voltage on the MB.
Good luck
John