Power supply, Motherboard, or something else?

[Jeff]

One of my desktops (built a few years ago) right now not only won't boot,
but won't even get to the bios. I get no video output at all. This is a
fanless system with fanless power supply so it's a bit harder to tell what's
going on. When I hit the power button, I can hear it click on. Some type of
power is getting to the MB, since the power light on the MB is on. When I
attach a case fan to the motherboard it starts for a second and then shuts
off. If I push and hold the power button, I can hear the power supply click
off. I don't have a spare power supply right now that isn't already
installed in a computer, so it will be harder for me to test the machine
with a different PS. Since I can hear the PS turn on and off and the fan
runs briefly, I suspect that it isn't the power supply and is likely the MB.

Any ideas about how I might figure out exactly what the problem is before I
start taking this thing apart?

Thanks

Jeff

 

[Rodney Pont]

One of my desktops (built a few years ago) right now not only won't boot,
but won't even get to the bios. I get no video output at all. This is a
fanless system with fanless power supply so it's a bit harder to tell what's
going on. When I hit the power button, I can hear it click on. Some type of
power is getting to the MB, since the power light on the MB is on. When I
attach a case fan to the motherboard it starts for a second and then shuts
off. If I push and hold the power button, I can hear the power supply click
off. I don't have a spare power supply right now that isn't already
installed in a computer, so it will be harder for me to test the machine
with a different PS. Since I can hear the PS turn on and off and the fan
runs briefly, I suspect that it isn't the power supply and is likely the MB.

Any ideas about how I might figure out exactly what the problem is before I
start taking this thing apart?

Either you get your crystal ball out or you take a power supply out of
one of your other systems and try it in this one. I'm assuming that if
you had a meter you would have used it.

 

[Flasherly]

One of my desktops (built a few years ago) right now not only won't boot,
but won't even get to the bios. I get no video output at all. This is a
fanless system with fanless power supply so it's a bit harder to tell what's
going on. When I hit the power button, I can hear it click on. Some type of
power is getting to the MB, since the power light on the MB is on. When I
attach a case fan to the motherboard it starts for a second and then shuts
off. If I push and hold the power button, I can hear the power supply click
off. I don't have a spare power supply right now that isn't already
installed in a computer, so it will be harder for me to test the machine
with a different PS. Since I can hear the PS turn on and off and the fan
runs briefly, I suspect that it isn't the power supply and is likely the MB.

Any ideas about how I might figure out exactly what the problem is before I
start taking this thing apart?

Been there, done that. But, no, your presumption the PS unit is good
isn't -- the MB is just as likely good and there are other issues (not
to rule out the PS). Having another PS in another computer, thing
that's cool about that, is it starts getting easier each time such
situations arise (damn, no spare). Best to pull the good/working one
out for a test pwr-up to see what's revealed, deductively/logically
speaking. Something different is just as likely to happen. Although
you could start simply in another direction, like pulling everything
on your fanless system, one at a time, that's not necessary for a boot
-- to include cleaning, at least reseating your memory contacts, along
with doublechecking all plugs are seated properly;- swap
plugs/contacts, as well, when duplicates are optionally available. A
fault might reveal itself and pop up. I've only had one, so far, that
I reduced to a grounding-issue from case standoffs. I take them right
down to a bootable MB on a towel, with a good PS, vid and keyboard;-
then if it doesn't boot, I might worry about a MB.

Never had a MB that "lost it," so to speak, although I've worn quite a
few down to the point they'll exhibited anomalies first, not fail. Any
MB I've "worn down into a state of senility" was way long past an
update, anyway. They're some pretty tough ol' beastards, the better
made brands, in my experience. (Didn't use to, but I'm now a firm
believer in researching/buying only Top Notch PS makes.)

Hey, I've gotten so bad, I only use one maybe two "thumb-screws" to
hold in a PS;- cases, hell, screw the side opposite/parallel to the
MB, which I never bother anymore putting back on. Not a hostile
environ, I try watch what I'm doing with open computers laying around.
They do run a little cooler and it's pretty easy getting in and out
when need to "change things around" a bit.

Pull your working PS, plug it in and see what happens. If it doesn't
come up, tear it down, try again with it rebuild it on a towel instead
of inside a case. (I've a spare jumper block and switches pulled from
an old case I was probably using for assembling on a towel;- they're
logical momentary-on states, anyway, and should be able to be shorted
for a jumpstart.)

 

[Paul]

One of my desktops (built a few years ago) right now not only won't
boot, but won't even get to the bios. I get no video output at all. This
is a fanless system with fanless power supply so it's a bit harder to
tell what's going on. When I hit the power button, I can hear it click
on. Some type of power is getting to the MB, since the power light on
the MB is on. When I attach a case fan to the motherboard it starts for
a second and then shuts off. If I push and hold the power button, I can
hear the power supply click off. I don't have a spare power supply right
now that isn't already installed in a computer, so it will be harder for
me to test the machine with a different PS. Since I can hear the PS turn
on and off and the fan runs briefly, I suspect that it isn't the power
supply and is likely the MB.

Any ideas about how I might figure out exactly what the problem is
before I start taking this thing apart?

Thanks

Jeff

You need a multimeter.

The ATX PSU "comes in two pieces". Two separate switching circuits
exist in the supply. The +5VSB powers USB ports and supervisor logic
(any logic which turns the computer on and off). The other three rails
are the main power rails, and a bigger portion of the circuit
is associated with that.

ATX PSU

AC Input ------+--- +5VSB circuit <--- controlled by switch on back
|
+--- +3.3/5.0/12V main section <--- controlled by PS_ON#

On an Asus motherboard (with some new recent exceptions), there
will be a green LED which runs off +5VSB. So you can tell the
switcher for +5VSB is running. The +5VSB is a "supervisor voltage"
and powers the logic that makes the rest of the machine work.

Your "click" symptom suggests it's not an issue with getting PS_ON#
to work, and turn on the main rails.

+5VSB (0.0V level +5VSB
| means "run please") |
Pullup \_ Pullup
Resistor \ Resistor
| PS_ON# |
PWR X----+---- Motherboard ---- Open -------------------+- ... control
/ logic Collector (to of main
| GND X----+ Driver ATX + PSU
| | supply) | section
(Front GND GND
Panel
Switch - normally open, momentarily close to operate)

To test the PSU, you could

1) Connect a fan directly to a Molex or SATA 15 pin connector.
This usually requires an adapter cable you might not have in
your junk drawer. I actually bought some fans once, just to get
the adapter cable that came in the box Running the fan directly
off a Molex, makes a simple way to check +12V is there. It does not
verify the exact voltage. For that you need...

2) Multimeter, harbor freight, $20

The multimeter, set to 20V full scale, and with the probes
in the volt/ohm red and black holes, can be used to check
the voltages. Note that the twits who designed this particular
meter, didn't use black plastic for the right-most ground terminal
The 20V DC scale is on the upper right, near the blue button. It's
possible to get a quality meter for $20 - just check the reviews
for comments about whether the thing is crappy or not.

http://www.amazon.com/Etekcity®-Digital-Multimeter-Backlit-LCD/dp/B00KHP6EIK

My crystal ball guess, is the fanless PSU has died. While
it "clicked", perhaps one of the rails is weak, and there
is not sufficient voltage to run things.

My first IBM PC, the power supply failed on it. The 12V output
runs at 12V when I connect one 12V 0.1A fan to it. If I connect
two fans, or a hard drive, the 12V rail drops to 6V. Which
means the outputs are a bit weak. It's only able to make
about 5% of the output power it used to make. And I tested
by grounding PS_ON# directly, with a ground wire.

The PS_ON# control signal isn't purely digital. A level
of 5V on the line, keeps the supply turned off. A level
of 0.4-0.7V or so (logic low), turns it on. The "#" in the
signal name, means the signal is "active low". Now, it is
possible to cause a power supply to have a weak output,
by feeding that logic signal a 1.5V to 2.0V level or so.
It turns the supply "half on", using half the expected voltage.
It makes the 12V weak, and unable to "hold up" a motherboard.
So a weak supply isn't always a supply fault, but that
exact set of circumstances isn't too common.

I did a walkthrough on this with poster "Adam" in a recent
thread, which is where my stick art diagrams come from.
He used a multimeter, and since his fans would not run,
the immediate suspicion was motherboard (no working PS_ON#).
And a swapped motherboard, brought things up. Adam did a separate
power supply test (grounding PS_ON#, checking for signs
of power). But you can do something like that, with a
newly purchased multimeter, and check to see if proper
voltages are there after the "click".

A power supply does not need a relay to work. But some
of the supplies with no on/off switch at the back of the
computer, they use a relay to apply mains power to themselves.
That's a typical Apple trick, and a few Dells maybe, have that.
The unit "clicks" a couple seconds after being plugged in,
after which the green LED (motherboard power monitor LED),
may be visible, and proof that the supervisor voltage
is available. The +5VSB is also used to charge tablets
and the like, via the USB port, when the computer is
soft off.

This site has plenty of pictures and tables, so you can
probe stuff and check for voltages. You can even probe
the main ATX PSU connector when it is plugged in. You connect
the black wire, to an I/O screw on the back of the computer.
As the metal around the I/O area is grounded. You can then use
the red probe, and poke where the wire goes into the plastic
shell of the connector. Enough exposed metal exists in there, to
take electrical readings off each wire. While the PC is running.
By only having to hold the red probe in your hand, you're
less likely to short stuff out.

http://www.playtool.com/pages/psuconnectors/connectors.html

And these tests are a lot easier to do, if the motherboard
and PSU are pulled out of the box, and tested on your
kitchen table. With appropriate precautions being taken
so the video card doesn't fall over, or get pulled out of
the slot. Be very careful with the plugin cards, as they
can easily get pulled from a slot and damage things in the
process. Having the electronics on the table, makes it easier
to get meter readings, but also makes it easier to
damage a card or motherboard.

Some computer cases, make it virtually impossible to pull
a populated motherboard out of the case. There is a stiffener
bar with rivets, to hold the chassis square, which prevents
easy removal. On my latest build, I was able to lower the
whole thing into place, in spite of one of those bars. So
sometimes, you get lucky.

Paul

 

[Rodney Pont]

You need a multimeter.

To be honest I don't think a meter will help in this situation. We know
the 5VSB is there because the led on the motherboard is on and we know
it's sufficient to turn on the PSU because the fan starts and then
stops and I don't think that will give time for a meter reading.

The OP could unplug the disc drive, I've seen them pull a psu down and
give these symptoms, a one week old 2TB Seagate drive earlier this year
(replaced under warranty).

 

[Paul]

To be honest I don't think a meter will help in this situation. We know
the 5VSB is there because the led on the motherboard is on and we know
it's sufficient to turn on the PSU because the fan starts and then
stops and I don't think that will give time for a meter reading.

The OP could unplug the disc drive, I've seen them pull a psu down and
give these symptoms, a one week old 2TB Seagate drive earlier this year
(replaced under warranty).

Sure. There's nothing wrong with an ad-hoc "try stuff"
approach. On a computer, this is called "simplification"
for want of a better word. Try removing stuff, a bit at
a time, and look for a change in symptoms.

You can also listen for beep codes, assuming the computer
has something connected to the SPKR front panel pins. Even
with pulling video card and RAM sticks, if you get a beep code
it tells you the CPU is getting power and the CPU is running
BIOS code. And that's half the motherboard tested right there.

So there are a ton of ad-hoc tests, and interesting results
to examine, to go further. It's all a question of whether
a person wants to write out a flow chart, every time this
happens

And if you do volunteer a flow chart, it needs a lot of details.
For example, once I suggested to someone, they pull the CMOS
CR2032 battery and test it. And because I didn't give details
on how to get the battery out, they managed to ruin the battery
socket. That means I have to modify my suggested procedures
a bit, like specify the purchase of a multimeter, probe the
top surface of the CMOS battery and get a reading off it. As
that is less dangerous, and a person won't snap off the
battery socket while working on it. At least, at first.

Paul

 

[Jeff]

It appears that it is the power supply. I was able to find a spare and after
plugging it in, the fan I plugged in stays on and so does the case's power
light. The problem I will have is that the machine is a discontinued Zalman
TNN300 totally noiseless with built-in power supply. I ran into one other
post on-line where someone with more electrical experience than I have was
speaking about attempting to repair the PS, but nothing else. I've emailed
the merchant who sold me the case to see whether they know of an option.
From what I gather, there was an external power supply for desktops made at
one point, but it looks like that was discontinued also.


Any ideas?
(hard for me to believe that someone couldn't figure out how to remove a
cmos battery! - sounds like someone who should even be opening the case)



"Paul" wrote in message

To be honest I don't think a meter will help in this situation. We know
the 5VSB is there because the led on the motherboard is on and we know
it's sufficient to turn on the PSU because the fan starts and then
stops and I don't think that will give time for a meter reading.

The OP could unplug the disc drive, I've seen them pull a psu down and
give these symptoms, a one week old 2TB Seagate drive earlier this year
(replaced under warranty).

Sure. There's nothing wrong with an ad-hoc "try stuff"
approach. On a computer, this is called "simplification"
for want of a better word. Try removing stuff, a bit at
a time, and look for a change in symptoms.

You can also listen for beep codes, assuming the computer
has something connected to the SPKR front panel pins. Even
with pulling video card and RAM sticks, if you get a beep code
it tells you the CPU is getting power and the CPU is running
BIOS code. And that's half the motherboard tested right there.

So there are a ton of ad-hoc tests, and interesting results
to examine, to go further. It's all a question of whether
a person wants to write out a flow chart, every time this
happens

And if you do volunteer a flow chart, it needs a lot of details.
For example, once I suggested to someone, they pull the CMOS
CR2032 battery and test it. And because I didn't give details
on how to get the battery out, they managed to ruin the battery
socket. That means I have to modify my suggested procedures
a bit, like specify the purchase of a multimeter, probe the
top surface of the CMOS battery and get a reading off it. As
that is less dangerous, and a person won't snap off the
battery socket while working on it. At least, at first.

Paul

 

[Loren Pechtel]

One of my desktops (built a few years ago) right now not only won't boot,
but won't even get to the bios. I get no video output at all. This is a
fanless system with fanless power supply so it's a bit harder to tell what's
going on. When I hit the power button, I can hear it click on. Some type of
power is getting to the MB, since the power light on the MB is on. When I
attach a case fan to the motherboard it starts for a second and then shuts
off. If I push and hold the power button, I can hear the power supply click
off. I don't have a spare power supply right now that isn't already
installed in a computer, so it will be harder for me to test the machine
with a different PS. Since I can hear the PS turn on and off and the fan
runs briefly, I suspect that it isn't the power supply and is likely the MB.

Any ideas about how I might figure out exactly what the problem is before I
start taking this thing apart?

A power supply that doesn't put out enough power or not good power
will show exactly this failure.

There's a short time that it's allowed to put out an inadequate
voltage but once that time is up there's a deadman switch that kills
it if the voltages are unacceptable.

It puts out enough power to run the fan but one or more rails aren't
to up the correct voltage when the timer runs out and the deadman
kills it.

(The purpose of the deadman is to kill it before the voltage gets far
enough off spec that the computer might do errant things--like write
crap to the HD.)

 

[Loren Pechtel]

(hard for me to believe that someone couldn't figure out how to remove a
cmos battery! - sounds like someone who should even be opening the case)

I can't see the connection to the thread.

I have had the experience, though--in a laptop. Swapping it would be
a triviality, finding how to get to it is decidedly non-trivial. (The
service manual doesn't even say where it's hiding.)

 

[Paul]

It appears that it is the power supply. I was able to find a spare and
after plugging it in, the fan I plugged in stays on and so does the
case's power light. The problem I will have is that the machine is a
discontinued Zalman TNN300 totally noiseless with built-in power supply.
I ran into one other post on-line where someone with more electrical
experience than I have was speaking about attempting to repair the PS,
but nothing else. I've emailed the merchant who sold me the case to see
whether they know of an option. From what I gather, there was an
external power supply for desktops made at one point, but it looks like
that was discontinued also.


Any ideas?

The sad part is, the state of the Zalman business right now.
They were bought by some other corporation, then the
other corporation had financial trouble. It's expected Zalman could
survive, but I don't know in the interim, what it might mean
for customer service. And whether you could still contact them
for suggestions.

That power supply has a fairly unique form factor. It could be
that some of the power components are mated to one side of the
supply, so the heat can flow into the case wall.

There are (or were) some fanless PSUs, up to around 400W. But
at least some of these, they're probably relying on airflow
from remaining fans in the computer case, to help the supply
meet the power rating. If the supply was put into a tight box,
it would likely overheat. Whereas the Zalman solution, is more
likely to be using conduction rather than convection.

Someone on the badcaps forum tried to work on a Zalman supply,
and couldn't figure it out. It appeared in their case, that
the Active PFC front end burned up. That could happen, if
the TNN300 was powered by a non-sine wave UPS. There have
been cases from when Active PFC first came out, where the
kind of UPS used, influenced the health of the power supply.
One of the side effects of Active PFC, is it places more
DC on the high voltage side of the supply. So instead of
320V on the hot side of the main cap, it might be 380V or so.
This is all part of how the active PFC stage is able to adjust
the phase angle of the current the supply draws. The naive
PFC design relies on the input waveform always being a sine
wave (as the PFC strives to draw a current waveform, which
matches the shape of the incoming voltage waveform). When a
square wave UPS is connected to one of those supplies, then the PFC
is trying to make the current draw look like a matching square
wave. Which to my way of thinking, could lead to some
interesting results (because there is still a filter on
the input stage, which has to eat the exotic waveform
coming from the PFC).

Now you know why Paul is careful not to buy Active PFC supplies.
Not because they're not good supplies, but Paul knows his
UPS is one of the bad kind I have to make do with my
current contingent of supplies, because it would be
relatively hard to find one without some PFC considerations.
And I plan to get a few more years out of my $300 UPS.

Another source of power would be a Pico supply, but they're
not powerful enough for anything but small projects. You
would need a laptop load, or a mini-ITX motherboard, to be
in range of the power capabilities of one of these.

http://www.mini-itx.com/store/?c=10#picoPSU-160-XT

You could also place a regular ATX outside the Zalman, and
run 24 pin extender cables. A pathetic solution, but, it's
another way to do it.

http://www.amazon.com/StarTech-8-Inch-Power-Extension-ATX24POWEXT/dp/B000FL60AI

Fanless Seasonic, with modular cabling. Always check the
reviews on the fanless ones, to get some idea the kind
of electrical load they've been tested with (by te
reviewers). And yes, this is active PFC. I can't imagine
them not doing that now.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151097

Paul

 

[Jeff]

Umm,

I will have to read your reply another time or two to digest it, but I got
the basic idea. The machine went bad not long after I started using a new
(and less-expensive than my old one) UPS after I moved overseas and found
out that while my computers were dual voltage, the expensive UPS I had in
the US was not.

I saw the discussion on the badcaps forum you mentioned.

What's probably going to occur is that I'm going to have to scrap the entire
Zalman case and put the components into another case.

So do I understand correctly that a non-sine wave UPS is inferior to and
less expensive than a sine wave version?

I seem to remember that the one I purchased was less expensive than others
of the same brand for some reason that I didn't understand.




"Paul" wrote in message

It appears that it is the power supply. I was able to find a spare and
after plugging it in, the fan I plugged in stays on and so does the case's
power light. The problem I will have is that the machine is a discontinued
Zalman TNN300 totally noiseless with built-in power supply. I ran into one
other post on-line where someone with more electrical experience than I
have was speaking about attempting to repair the PS, but nothing else.
I've emailed the merchant who sold me the case to see whether they know of
an option. From what I gather, there was an external power supply for
desktops made at one point, but it looks like that was discontinued also.


Any ideas?

The sad part is, the state of the Zalman business right now.
They were bought by some other corporation, then the
other corporation had financial trouble. It's expected Zalman could
survive, but I don't know in the interim, what it might mean
for customer service. And whether you could still contact them
for suggestions.

That power supply has a fairly unique form factor. It could be
that some of the power components are mated to one side of the
supply, so the heat can flow into the case wall.

There are (or were) some fanless PSUs, up to around 400W. But
at least some of these, they're probably relying on airflow
from remaining fans in the computer case, to help the supply
meet the power rating. If the supply was put into a tight box,
it would likely overheat. Whereas the Zalman solution, is more
likely to be using conduction rather than convection.

Someone on the badcaps forum tried to work on a Zalman supply,
and couldn't figure it out. It appeared in their case, that
the Active PFC front end burned up. That could happen, if
the TNN300 was powered by a non-sine wave UPS. There have
been cases from when Active PFC first came out, where the
kind of UPS used, influenced the health of the power supply.
One of the side effects of Active PFC, is it places more
DC on the high voltage side of the supply. So instead of
320V on the hot side of the main cap, it might be 380V or so.
This is all part of how the active PFC stage is able to adjust
the phase angle of the current the supply draws. The naive
PFC design relies on the input waveform always being a sine
wave (as the PFC strives to draw a current waveform, which
matches the shape of the incoming voltage waveform). When a
square wave UPS is connected to one of those supplies, then the PFC
is trying to make the current draw look like a matching square
wave. Which to my way of thinking, could lead to some
interesting results (because there is still a filter on
the input stage, which has to eat the exotic waveform
coming from the PFC).

Now you know why Paul is careful not to buy Active PFC supplies.
Not because they're not good supplies, but Paul knows his
UPS is one of the bad kind I have to make do with my
current contingent of supplies, because it would be
relatively hard to find one without some PFC considerations.
And I plan to get a few more years out of my $300 UPS.

Another source of power would be a Pico supply, but they're
not powerful enough for anything but small projects. You
would need a laptop load, or a mini-ITX motherboard, to be
in range of the power capabilities of one of these.

http://www.mini-itx.com/store/?c=10#picoPSU-160-XT

You could also place a regular ATX outside the Zalman, and
run 24 pin extender cables. A pathetic solution, but, it's
another way to do it.

http://www.amazon.com/StarTech-8-Inch-Power-Extension-ATX24POWEXT/dp/B000FL60AI

Fanless Seasonic, with modular cabling. Always check the
reviews on the fanless ones, to get some idea the kind
of electrical load they've been tested with (by te
reviewers). And yes, this is active PFC. I can't imagine
them not doing that now.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151097

Paul

 

[Paul]

Umm,

I will have to read your reply another time or two to digest it, but I
got the basic idea. The machine went bad not long after I started using
a new (and less-expensive than my old one) UPS after I moved overseas
and found out that while my computers were dual voltage, the expensive
UPS I had in the US was not.

I saw the discussion on the badcaps forum you mentioned.

What's probably going to occur is that I'm going to have to scrap the
entire Zalman case and put the components into another case.

So do I understand correctly that a non-sine wave UPS is inferior to and
less expensive than a sine wave version?

I seem to remember that the one I purchased was less expensive than
others of the same brand for some reason that I didn't understand.

The step approximation to a sine is definitely cheaper than a
pure sine UPS. That's how you can make a $50 UPS.

The blue waveform here, is what my UPS would be doing. It's
a step, which crudely approximates a sine wave. It would have
a high harmonic content.

http://ts2.mm.bing.net/th?id=HN.608006724868444069&pid=15.1&P=0

I'm not sure what the red waveform in that picture is meant to imply.
I thought for pure sine, they're a lot better approximation than that.

The red waveform here isn't bad. Maybe not "home theater"
quality (in the Monster cable sense, not the practical sense),
but probably good enough for some Active PFC computer supplies.

http://www.acousticfrontiers.com/wp-content/uploads/2013/04/True%20vs%20stepped%20sine.png

This is an example of a cheap pure sine. It must be in the
bottom tier, based on the failure reports from the users.
A three year battery life isn't exactly something to
celebrate. On my UPS, I got ten years from the battery
(amazing). And I purchased a new battery cartridge and
it's as good as new.

http://www.newegg.com/Product/Product.aspx?Item=N82E16842102133

For some reason, this one has better reviews, and is
very similar to the previous one. This one has AVR
(automatic voltage regulation), where the unit can
buck or boost the AC which is still flowing from the
utility. Which is fine if your utility allows the
voltage to wander all over the place.

http://www.newegg.com/Product/Product.aspx?Item=N82E16842102134

There are an amazing number of different architectures
for UPS designs. And it's pretty hard to stay current
on how they're able to do this for the price point.
At one time, they would have been $1000 or so.

Those units don't have nearly enough runtime, if
you planned on "running off-grid" for a while
on a failure. THey're basically rated high enough,
so that you can do a clean shutdown on the computer,
and that's about all. That is, if you're running them
near the stated limits (the Watt or Volt-Ampere rating).

Paul

 

[larrymoencurly]

One of my desktops (built a few years ago) right now not only won't boot,
but won't even get to the bios. I get no video output at all. This is a
fanless system with fanless power supply so it's a bit harder to tell what's
going on. When I hit the power button, I can hear it click on. Some type of
power is getting to the MB, since the power light on the MB is on. When I
attach a case fan to the motherboard it starts for a second and then shuts
off. If I push and hold the power button, I can hear the power supply click
off. I don't have a spare power supply right now that isn't already
installed in a computer, so it will be harder for me to test the machine
with a different PS. Since I can hear the PS turn on and off and the fan
runs briefly, I suspect that it isn't the power supply and is likely the MB.

If it turns on, even briefly, it probably means that the main +5V (as
opposed to the +5Vstandby -- the thing that powers the motherboard LED)
is working, at least sort of. Fans running means the +12V is putting
out at least +5V - +6V. One way to test these is with a DVD or CD
drive. It doesn't matter whether it's SATA or PATA; just connect it
to the power supply, and if you can open and close the door through
the button, very likely the +12V and +5V are OK because these drives
won't work if those voltages are 10% below specs. But all this
leaves the +3.3V in question, which most motherboards need to
power many of the smaller chips, and I don't know how to test it
except with a multimeter. Cheap digital meters, including the ones
that are usually less than $3 or even free from Harbor Freight with
a coupon and any purchase, are fine for testing this.

So did the computer work when you tried the other power supply?

Could these products be covered by a credit card? Most cards
add up to a year of coverage over the manufacturer's warranty
if latter is up to 1 year (Mastercard), 3 years (Visa and,
more recently, Discover), and American Express (5 years). Coverage
don't apply until after the manufacturer's warranty has expired,
but if the manufacturer is out of business, you should be able
to contest this as a billing error because you paid for not just
the product but also its warranty and didn't get the warranty.

 

[Gremlin]

One of my desktops (built a few years ago) right now not only won't
boot, but won't even get to the bios. I get no video output at all.
This is a fanless system with fanless power supply so it's a bit
harder to tell what's going on. When I hit the power button, I can
hear it click on. Some type of power is getting to the MB, since
the power light on the MB is on. When I attach a case fan to the
motherboard it starts for a second and then shuts off. If I push
and hold the power button, I can hear the power supply click off. I
don't have a spare power supply right now that isn't already
installed in a computer, so it will be harder for me to test the
machine with a different PS. Since I can hear the PS turn on and
off and the fan runs briefly, I suspect that it isn't the power
supply and is likely the MB.

Any ideas about how I might figure out exactly what the problem is
before I start taking this thing apart?

Limiting options here aren't you? A multi meter, and power supply
tester, would be good things for your toolkit.

As you have another power supply available to you that you know is
working, I'd give it a shot with the system that seems to be down. I
know you said you didn't want to do that, but it's one of the quickest
troubleshooting steps you can take, without a multimeter and/or power
supply tester available. otherwise, I'd just use those first on the PS
currently in the dead computer.

At some point, you're going to have to mess with various components if
you intend to repair the system anyhow. Might as well start with
another power supply.

Going only from previous experience, this is nothing more than an
educated guess, but I'd say your system has a dead power supply.

 

[Diesel]

It appears that it is the power supply. I was able to find a spare
and after plugging it in, the fan I plugged in stays on and so does
the case's power light. The problem I will have is that the machine
is a discontinued Zalman TNN300 totally noiseless with built-in
power supply. I ran into one other post on-line where someone with
more electrical experience than I have was speaking about
attempting to repair the PS, but nothing else. I've emailed the
merchant who sold me the case to see whether they know of an
option. From what I gather, there was an external power supply for
desktops made at one point, but it looks like that was discontinued
also.

Oops. nevermind. I was obviously, late to the thread here.

 

[Jax]

Oops. nevermind. I was obviously, late to the thread here.

Why are you nym shifting within a single thread? You posted as
Gremlin and now as Diesel. You're BUSTED!

 

[John Kennerson]

Why are you nym shifting within a single thread? You posted as
Gremlin and now as Diesel. You're BUSTED!

Ignore the "insult" from a previous post, Jax.

I posted that I couldn't believe you didn't figure out that DuckLiar
was forging his own headers.

Glad to see your on board.

The BBS crap in SE is what told me for sure it he doing his own dirty
work and not some "forger".

 

[Bill]

You can get a power supply tester, that looks something like this:

http://img.weiku.com/waterpicture/2011/10/22/12/LED_power_supply_tester_634591876037711902_5.jpg


Or even something a bit more sophisticated like this one:

http://www.quietpc.com/images/products/x_psu_tester.jpg

Yousuf Khan

Thanks for posting this. It's nice to be aware of items like
this...pretty affordable too.

 

[Jeff]

I received the following suggested work-around for an external power supply
(the two links below) from the place I bought the case from a few years ago.
I might go for it at some point, but for now I have other machines to use.
One was built in a Moneual case. As I was reading up on this issue, I came
across some info on Zalman that elaborates upon what you've mentioned below.
Apparently, Moneual bought Zalman and then the CEOs engaged in some type of
fraud where they were claiming much higher sales than they actually had.
From what was claimed in the article I read on-line, this was done on
purpose in order to default on loans and use the money for other reasons. So
now when I look up Moneual to get info on my case, the only thing they are
currently selling is robotic vacuum cleaners. Bizarre.

By the way, I did hook up my Zalman machine to another power supply and it
booted just fine. I'll have to learn to use a meter in the future.

Thanks for the help and info.

http://www.amazon.com/gp/product/B0045WFZSQ/ref=oh_aui_detailpage_o04_s00?ie
=UTF8&psc=1

http://www.amazon.com/gp/product/B007XVD452/ref=oh_aui_detailpage_o04_s00?ie
=UTF8&psc=1


"Paul" wrote in message
The sad part is, the state of the Zalman business right now.
They were bought by some other corporation, then the
other corporation had financial trouble. It's expected Zalman could
survive, but I don't know in the interim, what it might mean
for customer service. And whether you could still contact them
for suggestions.

 

[Flasherly]

The sad part is, the state of the Zalman business right now.
They were bought by some other corporation, then the
other corporation had financial trouble. It's expected Zalman could
survive, but I don't know in the interim, what it might mean
for customer service. And whether you could still contact them
for suggestions.

Don't think I've bought from Zalman - noticed, but they were a little
to edgy on the high prices for my tastes No doubt certainly catchy and
a reasonably popular brand. Then, I'm invariably buying for the
highest matrices of standardization (components swap easily). There's
still a lot of leeway for styles, all kinds of mini/mid designs, and
such in that. I just like whatever gets a computational end through
fastest for the least monetary outlay over the longest foreseeable
time.