HP Pavilion 520n No Power - PLEASE HELP!

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D

D

Was working fine last night, woke up this morning & my pc was off so I
attempted to power on as usual except when I pushed the power button,
nothing happened. I even held it in for a few seconds & still nothing.
I did notice in the back right next to where the power cable plugs into
the pc that a green light was lit so there's power going to the pc, I
just can't turn the thing on with the power button. I then opened the
box & cleaned everything with a can of air but still....NOTHING. Does
anyone have any significant suggestions? Thanks in advance.
 
Was working fine last night, woke up this morning & my pc was off so I
attempted to power on as usual except when I pushed the power button,
nothing happened. I even held it in for a few seconds & still nothing.
I did notice in the back right next to where the power cable plugs into
the pc that a green light was lit so there's power going to the pc, I
just can't turn the thing on with the power button. I then opened the
box & cleaned everything with a can of air but still....NOTHING. Does
anyone have any significant suggestions? Thanks in advance.
Click to expand...


Unplug it from AC for 5 minutes (if you hadn't done so
already) then retry it. Examine the motherboard for vented
capacitors, cards or cables amiss. Clear CMOS (or remove
battery for a few minutes) with AC shut off or unplugged.

If you have a multimeter, measure power supply voltage
levels. Note whether fans are spinning when you press the
On button. Where exactly is this green light, on the power
supply casing itself?

Is it under warranty still?
A brief description of the major components might help,
and/or any changes made from the initial system
configuration (hardware, not software).
 
In all likelihood, either the power supply unit or the motherboard has
failed. The easiest diagnostic to run to decide which failed is to replace
the power supply unit with a known working one of adequate power output and
see if that fixes it. If it doesn't, time to look at the motherboard.
 
What I've done so far: I left the unit unplugged all day..used a brand
new power cable & plugged back into a different outlet (no surge
protector), reseated the memory, the video card, reseated the power
button wiring where it attaches to the board. Took the cmos battery out
then replaced back into compartment. Flipped the red voltage switch
then back to american voltage. Still no power, I DID however notice
both fans turned when I pushed the power button but ONLY once after a
re-attachment of the power cable. To see the fans move, you have to
disconnect the power cable then re-connect & the fans will turn once
when pushing the power button. I still have a green led light on the
power compartment on the back. But no powering up from the front. Most
of you mentioned replacing the power supply box...it didn't look
simple...is the wiring the same for all power boxes? In other words,
will I have the same amount of wires running to my drives & board etc.?
Thanks again in advance!
 
What I've done so far: I left the unit unplugged all day..used a brand
new power cable & plugged back into a different outlet (no surge
protector), reseated the memory, the video card, reseated the power
button wiring where it attaches to the board. Took the cmos battery out
then replaced back into compartment. Flipped the red voltage switch
then back to american voltage. Still no power, I DID however notice
both fans turned when I pushed the power button but ONLY once after a
re-attachment of the power cable. To see the fans move, you have to
disconnect the power cable then re-connect & the fans will turn once
when pushing the power button. I still have a green led light on the
power compartment on the back. But no powering up from the front. Most
of you mentioned replacing the power supply box...it didn't look
simple...is the wiring the same for all power boxes? In other words,
will I have the same amount of wires running to my drives & board etc.?
Thanks again in advance!
Click to expand...

It is relatively simple, it just screws in (usually), then
motherboard leads are keyed a plug per drive. Biggest
problem with OEM systems is often the lack of room to work
inside, it can take patience to route all the cables and
secure them away from fans (nylon wire ties come in handy if
you have any around).

Google for standard ATX power supply dimensions and pinout,
because it's possible HP used a proprietary PSU. Generally
the color scheme on the ATX connector can be a hint, but
even then an OEM may occasionally deviate on one of the
colors, but that color deviation still stays consistent in
which pins it goes to.

http://69.36.189.159/usr_1034/atx_on.gif

A multimeter would be the confirmation of this, and possibly
useful to see what the PSU output is like during that
interval where you first replug it and the fans briefly
start to spin. It does seem typical of a power supply
failure, but it's still possible some other component
shorting-out would produce similar symptoms.



IF it's standard, regular ATX or mATX (determine which), the
number of wires can depend on quality and wattage capacity
of the replacement. Typically HP boxes don't come with much
in them (drivewise at least, only 2), so the typical supply
should have more than enough cables. OEMs typically use
good quality but conservatively rated units so avoid the
temptation to buy same wattage in a generic or you'll end up
with a PSU that's worth less capacity.

If you linked to a picture of the inside and/or rear of the
unit it might assist someone in determining if it's
standard, or at least standard dimensions.
 
I'm getting somewhere...I unplugged all the drive connections just to
see if there was a short somewhere but still no power SO...I borrowed a
power supply box from a compaq, hooked up the main power connection on
the MB & low & behold..the thing powered right up. Am I to assume it's
indeed the power supply? If so I need to buy one that fits my unit
because the compaq supply was too large in physical size. Thanks.
 
I'm getting somewhere...I unplugged all the drive connections just to
see if there was a short somewhere but still no power SO...I borrowed a
power supply box from a compaq, hooked up the main power connection on
the MB & low & behold..the thing powered right up. Am I to assume it's
indeed the power supply? If so I need to buy one that fits my unit
because the compaq supply was too large in physical size. Thanks.
Click to expand...


Yes that "seems" to be the answer, providing there wan't
anything else hooked up to the original supply that was
faulty, and then the new supply worked only because it
wasn't also hooked up to that faulty part. While that's
possible, odds are it is just the power supply itself.

The easy assumption would be that the Compaq supply was
regular ATX and yours is mATX, except that Compaq also has
used some unusual PSU that are taller, have a 92mm rear
exhaust fan. A standard ATX is almost 3.5" tall (as mounted
in a typical case's top rear). mATX is about 2.5" tall but
more frequently oriented differently in a case... that would
be the "length" of it's shortest side ignoring any further
protrusion by a fan if one hangs down under the PSU. The
proprietary Compaq PSUs I"m thinking of are 3 7/8" tall.

"IF" you need a mATX, note whether the side that screws to
the back of the case is the 2nd longest side (dimension) or
the longest. mATX-L has the longest side mounted to case.
mATX-S has the 2nd longest. Most are -L but it is something
to be aware of as it will usually be much cheaper to buy a
decent (name brand) 3rd party PSU rather than one from HP.
 
D said:
What I’ve done so far: I left the unit unplugged all day..used a
brand
new power cable & plugged back into a different outlet (no surge
protector), reseated the memory, the video card, reseated the power
button wiring where it attaches to the board. Took the cmos battery
out
then replaced back into compartment. Flipped the red voltage switch
then back to american voltage. Still no power, I DID however notice
both fans turned when I pushed the power button but ONLY once after a
re-attachment of the power cable. To see the fans move, you have to
disconnect the power cable then re-connect & the fans will turn
once
when pushing the power button. I still have a green led light on the
power compartment on the back. But no powering up from the front. Most
of you mentioned replacing the power supply box...it didn’t look
simple...is the wiring the same for all power boxes? In other words,
will I have the same amount of wires running to my drives & board
etc.?
Click to expand...

It seems the power supply is where you start.
I’d just like to say I have a couple of power supplies for them I’m
never
likely to use..
Is the hard drive clicking while your trying to power the system up?
 
I'm getting somewhere...I unplugged all the drive connections
just to
see if there was a short somewhere but still no power SO...I
borrowed a
power supply box from a compaq, hooked up the main power
connection on
the MB & low & behold..the thing powered right up. Am I to
assume it's
indeed the power supply? If so I need to buy one that fits my
unit
because the compaq supply was too large in physical size.
Thanks.
Click to expand...

From memory some Compaq’s used the identical power supply bar the
mounting bracket (You can swap them over).
 
Looks like it was indeed the power supply, things have been running
smooth for the past few days. PC is quieter also. Thanks to all for the
tips.
 
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