PC boot fail

#11

Thanks 'Pen' I will get the meter on that now.

N

"Pen" <nospam (AT) nospam (DOT) com> wrote

Quote:

"Nigel Andrews" <nandrews2 (AT) yahoo (DOT) com> wrote in message
news:Y514g.685$E52.211 (AT) newsfe6-win (DOT) ntli.net...
Thanks all.

I have finally got around to trying all your suggestions.

The problem: PC fails to boot-up
The symptoms: no booting 'beep', monitor doesn't come out of sleep,
drive
light steady for 30 secs then goes out, keyboard lights flash but then
nothing.

Disconnecting all drives except the floppy doesn't change the situ' - the
drive doesn't access any floppy disc inserted.

There is an LED on the main board which is alight whenever there is mains
power connect to the PSU

The PSU and proc fans start when mains power is connected to the PSU and
then dies after a few secs

I don't see any voltage markings on the m/board (adjacent to the 20 way
connector) so still not sure what I should check to see if the PSU is
faulty.

For a while I could leave the PC on and then try a reboot later and it
would boot correctly. Now it always fails to boot.

Any more advice will be gratefully received.

Thanks
Nigel

"Arno Wagner" <me (AT) privacy (DOT) net> wrote in message
news:4b53h0Fvu0mhU1 (AT) individual (DOT) net...
Previously Nigel Andrews <nandrews2 (AT) yahoo (DOT) com> wrote:
Thanks both,

Presumably tho' it provides some power starting the discs and keyboard,
there are different 'stages' in the PSU which may have failed?
I will do some checks on the PSU outputs. Is there a page which gives
the
expected voltages on the leads?

For the expected voltages, just look at a diagram of the mainboard
connector. All are 5% tolerance, except for 12V and 5Vsb, they
have 10% tolerance. You may also need to check noise. If an output
fuilter capacitor is broken, the average voltages may still
be fine.

Arno

Go here, get the ATX specs for the power connector.
http://www.formfactors.org/developer...x/atxspecs.htm

#12

On Thu, 27 Apr 2006 10:33:28 GMT, "Nigel Andrews"
<nandrews2 (AT) yahoo (DOT) com> wrote:

Quote:

Thanks all.

I have finally got around to trying all your suggestions.

The problem: PC fails to boot-up
The symptoms: no booting 'beep', monitor doesn't come out of sleep, drive
light steady for 30 secs then goes out, keyboard lights flash but then
nothing.

Disconnecting all drives except the floppy doesn't change the situ' - the
drive doesn't access any floppy disc inserted.

There is an LED on the main board which is alight whenever there is mains
power connect to the PSU

The PSU and proc fans start when mains power is connected to the PSU and
then dies after a few secs

I don't see any voltage markings on the m/board (adjacent to the 20 way
connector) so still not sure what I should check to see if the PSU is
faulty.

A meter doesn't always tell you if it is good, just try a new one and
see what happens.

#13

Thanks,

I will give the meter a try first before I spend on a new PSU, tho' it may
come to that in the end.

I am not sure if I will find any voltages on that plug anyway as the power
switch doesn't have any effect if the plug is not connected to the board. It
will be difficult to tap the right contacts when the plug is connected.

Nigel

"Chris Hill" <chill_mapsfree_000 (AT) centurytel (DOT) net> wrote

Quote:

On Thu, 27 Apr 2006 10:33:28 GMT, "Nigel Andrews"
nandrews2 (AT) yahoo (DOT) com> wrote:

Thanks all.

I have finally got around to trying all your suggestions.

The problem: PC fails to boot-up
The symptoms: no booting 'beep', monitor doesn't come out of sleep, drive
light steady for 30 secs then goes out, keyboard lights flash but then
nothing.

Disconnecting all drives except the floppy doesn't change the situ' - the
drive doesn't access any floppy disc inserted.

There is an LED on the main board which is alight whenever there is mains
power connect to the PSU

The PSU and proc fans start when mains power is connected to the PSU and
then dies after a few secs

I don't see any voltage markings on the m/board (adjacent to the 20 way
connector) so still not sure what I should check to see if the PSU is
faulty.

A meter doesn't always tell you if it is good, just try a new one and
see what happens.

#14

Pardon my naiveté.

I am not getting any voltages on the 20 way connector when disconnected, but
when I connect it the fans start and then stop so there must be some sensing
there. How can I get the PSU to run with the main connector disconnected? Or
do I have to get the meter probes on to the contacts somehow with it
connected to the main board?!

Thanks again

Nigel

"Arno Wagner" <me (AT) privacy (DOT) net> wrote

Quote:

Previously Nigel Andrews <nandrews2 (AT) yahoo (DOT) com> wrote:
Thanks both,

Presumably tho' it provides some power starting the discs and keyboard,
there are different 'stages' in the PSU which may have failed?
I will do some checks on the PSU outputs. Is there a page which gives the
expected voltages on the leads?

For the expected voltages, just look at a diagram of the mainboard
connector. All are 5% tolerance, except for 12V and 5Vsb, they
have 10% tolerance. You may also need to check noise. If an output
fuilter capacitor is broken, the average voltages may still
be fine.

Arno

#15

"Nigel Andrews" wrote

Quote:

Pardon my naiveté.

I am not getting any voltages on the 20 way connector when disconnected, but
when I connect it the fans start and then stop so there must be some sensing
there. How can I get the PSU to run with the main connector disconnected? Or
do I have to get the meter probes on to the contacts somehow with it
connected to the main board?!

Basicly, short pin 14 (green) to ground (any black) and the PSU should power up.

Google... test atx psu

Here's one result:
http://modtown.co.uk/mt/article2.php?id=psumod

#16

MasterB

Thanks, that is just what I need.

Nigel

"MasterBlaster" <Nobody's.Home (AT) My (DOT) Place> wrote

Quote:

"Nigel Andrews" wrote

Pardon my naiveté.

I am not getting any voltages on the 20 way connector when disconnected,
but
when I connect it the fans start and then stop so there must be some
sensing
there. How can I get the PSU to run with the main connector disconnected?
Or
do I have to get the meter probes on to the contacts somehow with it
connected to the main board?!

Basicly, short pin 14 (green) to ground (any black) and the PSU should
power up.

Google... test atx psu

Here's one result:
http://modtown.co.uk/mt/article2.php?id=psumod

#17

I have finally gotten around to measuring the output on the PSU and they all
are there and appear to be the correct voltages.
So I am assuming the reason why it won't boot is due to a failure on the
m/board.

Someone suggests caps (capacitors) may have failed.

I probably need to get this to a repair centre and see if they will fix it.

Thanks for help

Nigel

"Arno Wagner" <me (AT) privacy (DOT) net> wrote

Quote:

Previously Nigel Andrews <nandrews2 (AT) yahoo (DOT) com> wrote:
Thanks both,

Presumably tho' it provides some power starting the discs and keyboard,
there are different 'stages' in the PSU which may have failed?
I will do some checks on the PSU outputs. Is there a page which gives the
expected voltages on the leads?

For the expected voltages, just look at a diagram of the mainboard
connector. All are 5% tolerance, except for 12V and 5Vsb, they
have 10% tolerance. You may also need to check noise. If an output
fuilter capacitor is broken, the average voltages may still
be fine.

Arno

#18

On Fri, 05 May 2006 09:09:21 GMT, "Nigel Andrews"
<nandrews2 (AT) yahoo (DOT) com> wrote:

Quote:

I have finally gotten around to measuring the output on the PSU and they all
are there and appear to be the correct voltages.
So I am assuming the reason why it won't boot is due to a failure on the
m/board.

Vom readings don't mean much. Go ahead and take it somewhere; don't
be surprised when they replace the psu. You can tell bad caps by
looking at them; they'll be bulged on top or leaking; they look like
tiny cans with either a / or an x in the top of them.

#19

Thanks all for your help.

I took it into a repair shop and they faulted the graphics card!! Yes, I
was amazed too, and actually doubted the competence of the engineer! But
they swapped my card for another and it booted up fine/
I brought it home and swapped the faulty card for an old spare and it is all
running fine now!

I still don't see why a faulty graphics card should hold the PC from
booting-up at all, not even the familiar PC 'beep'!

Thanks to all for your help

Nigel

"Chris Hill" <chill_mapsfree_000 (AT) centurytel (DOT) net> wrote

Quote:

On Fri, 05 May 2006 09:09:21 GMT, "Nigel Andrews"
nandrews2 (AT) yahoo (DOT) com> wrote:

I have finally gotten around to measuring the output on the PSU and they
all
are there and appear to be the correct voltages.
So I am assuming the reason why it won't boot is due to a failure on the
m/board.

Vom readings don't mean much. Go ahead and take it somewhere; don't
be surprised when they replace the psu. You can tell bad caps by
looking at them; they'll be bulged on top or leaking; they look like
tiny cans with either a / or an x in the top of them.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

PC boot fail

Miscellaneous PC Hardware Miscellaneous PC hardware topics (comp.sys.ibm.pc.hardware.misc)

Re: PC boot fail - 04-27-2006 , 07:36 AM

Re: PC boot fail - 04-27-2006 , 08:52 AM

Re: PC boot fail - 04-27-2006 , 03:23 PM

Re: PC boot fail - 04-29-2006 , 06:22 AM

Re: PC boot fail - 04-29-2006 , 08:27 AM

Re: PC boot fail - 04-30-2006 , 07:39 AM

Re: PC boot fail - 05-05-2006 , 05:09 AM

Re: PC boot fail - 05-05-2006 , 10:31 AM

Re: PC boot fail - 05-06-2006 , 07:10 AM