Help with a +5V problem

  • Thread starter Thread starter Lanky Spanky
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Lanky Spanky

The +5 V on my Antec P/S (TruePower 380W) had been operating fine (4.8
- 4.9), but over the last few months it has slowly stepped down, and
now remains, in the low 4.5 V range. Is this normal or has the P/S
gone bad? I previously owned an Enermax 300W P/S, with the same
hardware components, that exhibited similar behavior.

It seems that this low voltage causes my vid card to misbehave.
Example: Occasionally when the monitor switches to display the login
screen for XP, it "goes crazy" showing pixelated random color vertical
lines, leaving the screen unrecognizable. This usually occurs on a
cold boot. A warm boot rectifies, at least so far, the problem.

Can anyone provide insights? Any thoughts would be greatly
appreciated.

Setup:
WinXP Pro
AMD T-bird 1Ghz socket A
A7M266
512 DDR RAM
GeForce 2Ti
Plextor Cd-RW
Creative CD-Rom
IBM HDD 15GB
Seagate HDD 250 GB
Promise Ultra100 TX-2 (for cd-rom drives)
Linksys Wireless Network card


Thanks
 
Could happen anytime if the decoupling capacitors on the power supply
rail start's to fail, what happens is when electrolytics start to
fail their ESR (Effective Series resistance) starts to rise, and
it'll end up looking like a resistor in series with a capacitor thus
preventing the capacitor from doing it's duty - removing hf ripples
from what should be a dc supply line.

This is only one of the possibilities there can be several others as
well.. the best bet is to try another unit and to check the voltage
'under load'.

In your case I would try another unit ensuring that the Wattage or
current that it is capable of supplying is equal to or greater than
the original, obviously the voltage must be 5V, doing this would
either blame or eliminate the unit ~ process of elimination.

Do note the the +ve and -ve connections must be the
correct way round.

Davy
 
Lanky Spanky said:
The +5 V on my Antec P/S (TruePower 380W) had been operating
fine (4.8 - 4.9), but over the last few months it has slowly stepped
down, and now remains, in the low 4.5 V range.
Click to expand...

How are you measuring that ? If its in the bios, that doesnt prove anything.

Measure it with a proper multimeter.
Is this normal
Click to expand...

Not if its real.
or has the P/S gone bad? I previously owned an Enermax 300W P/S,
with the same hardware components, that exhibited similar behavior.
Click to expand...
It seems that this low voltage causes my vid card to misbehave.
Example: Occasionally when the monitor switches to display the login
screen for XP, it "goes crazy" showing pixelated random color vertical
lines, leaving the screen unrecognizable. This usually occurs on a
cold boot. A warm boot rectifies, at least so far, the problem.
Click to expand...
Can anyone provide insights?
Click to expand...

It could be bad caps in the power supply if its real.
 
Lanky Spanky said:
The +5 V on my Antec P/S (TruePower 380W) had been operating fine (4.8
- 4.9), but over the last few months it has slowly stepped down, and
now remains, in the low 4.5 V range. Is this normal or has the P/S
gone bad?
Click to expand...

It's way out of spec. if those voltage readings are correct. 4.75V minimum,
5.25V maximum. Replace that power supply, quick. -Dave
 
Thanks for the info/feedback Rod. My readings were based on the bios
and motherboard monitor software. How would you suggest that I
measure the voltages?

I.e. take a multimeter and stick the leads into the power connectors
coming from the power supply (the connectors for the HDD, CD etc) or
go to the motherboard power connector (not sure how I would measure it
with the computer on).....


Are bad capacitors in the power supply a typical problem?


How are you measuring that ? If its in the bios, that doesnt prove anything.

Measure it with a proper multimeter.


Not if its real.




It could be bad caps in the power supply if its real.
Click to expand...

Lanky

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Thanks for the help Davy, Rod, and Dave. Much appreciated.


Lanky

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Lanky Spanky said:
Thanks for the info/feedback Rod. My readings were based
on the bios and motherboard monitor software. How would
you suggest that I measure the voltages?
Click to expand...
I.e. take a multimeter and stick the leads into the power connectors
coming from the power supply (the connectors for the HDD, CD etc)
Click to expand...

Yes, tho that doesnt give you access to the 3.3V rail.
or go to the motherboard power connector (not
sure how I would measure it with the computer on).....
Click to expand...

You can push the probe down the wire into the back of the
connector until it contacts the metal pin thats crimped onto the
wire. You only need to do with that with the 3.3V rail, its easier
to measure the rest at the power connectors for the drives.
Are bad capacitors in the power supply a typical problem?
Click to expand...

Yes, that problem has infested the industry.

The individual responsible should be publicly executed to encourage
the others to be more careful when stealing technology in future |-)
 
So here's what I got from plugging the multimeter in the power
connector:

+5V: Reads at 4.70 V
+12V: Reads at 11.98 V

Is the +5V out of spec? thoughts?

I've since swapped out my GeForce2 Ti with an older Fire GL1000 pro
(8MB ver) and this has stopped my display problems (though the card is
really slooooow.)

Lanky

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