Computer Help Forums

Computer Help Forum > TechieHQ Office > Newsgroup Archive > PC Hardware > Can bad caps on a motherboard kill a PSU?

Reply
Thread Tools Display Modes

Can bad caps on a motherboard kill a PSU?

 
 
spodosaurus
Guest

Posts: n/a
Thanked:


 
      Aug 12th, 07, 12:16 PM
Hi all,

In a recent thread here ("") I was testing out a new tool to quickly
diagnose whether a PCs issues were PSU related. Turns out the power
supply tester and the PSU were defective (behold the power and of the
multimeter). Anyway, The Antec TruePower 380 PSU is only about 26 months
old and seems a tad young to be dying seeing as my other Antec TruePower
380 is over four years old and running perfectly. The motherboard in the
system with the bad PSU is one of several Gigabyte boards I've owned
that have been affected by the bad capacitor issue. I'm wondering if the
buldging caps on the GA-7VTXE+ board could have caused the early demise
of the 5V rail on the PSU?

PSU readings on the 20 pin ATX connector:

Pins 1, 2, and 11 (3.3V): 3.28V (good)
Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
Pin 9 (5VSB): 5.05V steady (good)
Pin 10 (12V): 11.66V (good)
Pin 12 (-12V): -12.58V (good)

Ari

--
spammage trappage: remove the underscores to reply
Many people around the world are waiting for a marrow transplant. Please
volunteer to be a marrow donor and literally save someone's life:
http://www.abmdr.org.au/
http://www.marrow.org/
 
Reply With Quote
 
 
 
 
Paul
Guest

Posts: n/a
Thanked:


 
      Aug 12th, 07, 1:15 PM
spodosaurus wrote:
> Hi all,
>
> In a recent thread here ("") I was testing out a new tool to quickly
> diagnose whether a PCs issues were PSU related. Turns out the power
> supply tester and the PSU were defective (behold the power and of the
> multimeter). Anyway, The Antec TruePower 380 PSU is only about 26 months
> old and seems a tad young to be dying seeing as my other Antec TruePower
> 380 is over four years old and running perfectly. The motherboard in the
> system with the bad PSU is one of several Gigabyte boards I've owned
> that have been affected by the bad capacitor issue. I'm wondering if the
> buldging caps on the GA-7VTXE+ board could have caused the early demise
> of the 5V rail on the PSU?
>
> PSU readings on the 20 pin ATX connector:
>
> Pins 1, 2, and 11 (3.3V): 3.28V (good)
> Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
> Pin 9 (5VSB): 5.05V steady (good)
> Pin 10 (12V): 11.66V (good)
> Pin 12 (-12V): -12.58V (good)
>
> Ari
>


(Your motherboard ?)
http://www.fmc.com.tw/product/gigamb/pic/7vtxe+.jpg

Does the voltage on the 5V rail, pop up to normal levels
if the supply is not powering that particular motherboard ?

It could be that the 4.68V level is there, because an extreme
amount of amps are being drawn. That is one reason I like to
have a clamp-on DC ammeter, to quickly check the current draw,
and detect an overload in progress. What you do with the clamp-on
ammeter, is open the jaws, and place the jaws around all the
5V wires at the same time. The clamp-on ammeter can sum the
current flow in all the wires, and give a total 5V ampere reading
flowing into the motherboard. And because the meter is non-contact,
you don't need to cut wires or anything. The meter uses Hall Probe
technology, and senses the magnetic field. The only caveat, is
limited bandwidth, and the inability to handle complex AC
waveforms properly (does a lousy job of measuring standby power
flowing in the AC line cord).

A 60W Athlon would be 5V @ 12A. The Vcore converter is 90% efficient
or less, so the amps need to be bumped to 12/0.90 = 13.3 amps. So,
if measuring the 5V into the board, I'd expect to see a bit more
current than that, when the board is running Prime95 or CPUBurn.
How much more than 13.3 amps, depends on what other stuff runs
off +5V.

This is my meter. The 40 amps DC range is good for motherboards.
I use the 400 amp DC range, to work on my car :-) Normal multimeter
current ranges, seldom exceed about 10 amps. These are very handy
to have, and if your business has a budget for test equipment,
add one to the bench.

http://exphil.com/images/products/Extech/380947.jpg

The lifetime of a power supply, could be affected by the load
placed on it. Some of the Antec supplies are known to use a
poor brand of caps. All capacitors are sensitive to temperature,
and the higher the temp, the faster they dry out. Which is
one reason I am not happy to see the fan spin so slow on some
power supplies. Higher fan speed means lower internal PSU
temp and longer life.

Paul
 
Reply With Quote
 
 
 
 
spodosaurus
Guest

Posts: n/a
Thanked:


 
      Aug 12th, 07, 1:42 PM
Paul wrote:
> spodosaurus wrote:
>> Hi all,
>>
>> In a recent thread here ("") I was testing out a new tool to quickly
>> diagnose whether a PCs issues were PSU related. Turns out the power
>> supply tester and the PSU were defective (behold the power and of the
>> multimeter). Anyway, The Antec TruePower 380 PSU is only about 26
>> months old and seems a tad young to be dying seeing as my other Antec
>> TruePower 380 is over four years old and running perfectly. The
>> motherboard in the system with the bad PSU is one of several Gigabyte
>> boards I've owned that have been affected by the bad capacitor issue.
>> I'm wondering if the buldging caps on the GA-7VTXE+ board could have
>> caused the early demise of the 5V rail on the PSU?
>>
>> PSU readings on the 20 pin ATX connector:
>>
>> Pins 1, 2, and 11 (3.3V): 3.28V (good)
>> Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
>> Pin 9 (5VSB): 5.05V steady (good)
>> Pin 10 (12V): 11.66V (good)
>> Pin 12 (-12V): -12.58V (good)
>>
>> Ari
>>

>
> (Your motherboard ?)
> http://www.fmc.com.tw/product/gigamb/pic/7vtxe+.jpg
>


Yes


> Does the voltage on the 5V rail, pop up to normal levels
> if the supply is not powering that particular motherboard ?


No. Same if it's powering the power supply tester and IDE drives, or
just the paperclip jumper method + IDE drives.

> A 60W Athlon would be 5V @ 12A.


Athlon XP 2400+

> The lifetime of a power supply, could be affected by the load
> placed on it. Some of the Antec supplies are known to use a
> poor brand of caps. All capacitors are sensitive to temperature,
> and the higher the temp, the faster they dry out. Which is
> one reason I am not happy to see the fan spin so slow on some
> power supplies. Higher fan speed means lower internal PSU
> temp and longer life.


The fan in this PSU spins at a constant speed (I don't even think this
PSU has the fan throttling circuitry and the motherboard connector that
the TruePower II series has). The case also has a small rear exhaust fan
(60mm Vantec Stealth) so ventilation could be better.

Ari


--
spammage trappage: remove the underscores to reply
Many people around the world are waiting for a marrow transplant. Please
volunteer to be a marrow donor and literally save someone's life:
http://www.abmdr.org.au/
http://www.marrow.org/
 
Reply With Quote
 
Paul
Guest

Posts: n/a
Thanked:


 
      Aug 12th, 07, 2:00 PM
spodosaurus wrote:
> Paul wrote:
>> spodosaurus wrote:
>>> Hi all,
>>>
>>> In a recent thread here ("") I was testing out a new tool to quickly
>>> diagnose whether a PCs issues were PSU related. Turns out the power
>>> supply tester and the PSU were defective (behold the power and of the
>>> multimeter). Anyway, The Antec TruePower 380 PSU is only about 26
>>> months old and seems a tad young to be dying seeing as my other Antec
>>> TruePower 380 is over four years old and running perfectly. The
>>> motherboard in the system with the bad PSU is one of several Gigabyte
>>> boards I've owned that have been affected by the bad capacitor issue.
>>> I'm wondering if the buldging caps on the GA-7VTXE+ board could have
>>> caused the early demise of the 5V rail on the PSU?
>>>
>>> PSU readings on the 20 pin ATX connector:
>>>
>>> Pins 1, 2, and 11 (3.3V): 3.28V (good)
>>> Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
>>> Pin 9 (5VSB): 5.05V steady (good)
>>> Pin 10 (12V): 11.66V (good)
>>> Pin 12 (-12V): -12.58V (good)
>>>
>>> Ari
>>>

>>
>> (Your motherboard ?)
>> http://www.fmc.com.tw/product/gigamb/pic/7vtxe+.jpg
>>

>
> Yes
>
>
>> Does the voltage on the 5V rail, pop up to normal levels
>> if the supply is not powering that particular motherboard ?

>
> No. Same if it's powering the power supply tester and IDE drives, or
> just the paperclip jumper method + IDE drives.
>
>> A 60W Athlon would be 5V @ 12A.

>
> Athlon XP 2400+
>
>> The lifetime of a power supply, could be affected by the load
>> placed on it. Some of the Antec supplies are known to use a
>> poor brand of caps. All capacitors are sensitive to temperature,
>> and the higher the temp, the faster they dry out. Which is
>> one reason I am not happy to see the fan spin so slow on some
>> power supplies. Higher fan speed means lower internal PSU
>> temp and longer life.

>
> The fan in this PSU spins at a constant speed (I don't even think this
> PSU has the fan throttling circuitry and the motherboard connector that
> the TruePower II series has). The case also has a small rear exhaust fan
> (60mm Vantec Stealth) so ventilation could be better.
>
> Ari
>


If the voltage had popped up, under no load, that would suggest that
the computer was loading the thing heavily. If the voltage is relatively
the same, with a load connected, or with no load, that tends to suggest
the supply for some reason, is always outputting on the low side.

4.68V is out of spec, so I'd replace it. Ideally, the supply should
have some loading on it, in case the design is such that it goes out
of regulation when the minimum current loading is not provided. But
since you've measure the voltage while in-circuit and got 4.68V,
then I'd change it out.

I do occasionally replace supplies, before they have a chance to fail.
On my first home build, I swapped out the supply when the fans started
to run erratically. A sign that the 12V was starting to "wobble".
That supply still works, but I won't be using it again. Using the
multimeter, I think it is still in spec - I just don't like to see
a supply that changes output voltage for no reason. (I.e. Fan speed
would change while sitting in the BIOS.)

Paul
 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
[SOLVED] mobo bad caps - reapirs ? Martin Slaney DIY Computers 12 Jan 29th, 06 5:40 PM
[SOLVED] CAPS vs no caps in email addresses Neil J Computing 6 Mar 12th, 05 12:48 AM
[SOLVED] Re: How to avoid motherboard with bad caps? Go with Albatron? Ed PC Hardware 1 Jan 28th, 04 8:52 AM
Re: How to avoid motherboard with bad caps? Go with Albatron? Al Dykes PC Hardware 2 Jan 27th, 04 12:10 PM
Re: How to avoid motherboard with bad caps? Go with Albatron? Frank PC Hardware 0 Jan 27th, 04 12:42 AM