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Signs of power supply problem

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Azeroth

Member
Joined
Apr 2, 2003
Location
Tampa, FL
I was wondering, what are some signs that my power supply isn't providing enough juice? Lately ive been having some weird problems where the computer doesnt post the first time i power it on in the mornings, but does once i press reset, was wondering if this is due to my power supply.
 

Ben721

Official X-Hour Man
Joined
Feb 3, 2002
A classic example of when it can't handle the load I believe is when like it just freezes.

What PSU do you have?
 
N

nerdlogic

Guest
One way is to check your rails and see how much they are fluctuating.
 

Myrdhinn

Registered
Joined
Jun 25, 2002
You might wish to inform people that some cheap voltmeters use a feedback circuit which can damage motherboards or any delicate electronic equipment when used. Caveat is, buy a decent digital voltmeter and make sure it uses no feedback.
 

larrymoencurly

Member
Joined
Jul 14, 2002
Could you explain how that feedback circuit works? I know from experience that having the voltmeter set to Ohms or Amps can casuse damage, :( but how can it cause damage while set to Volts, unless the circuitry is a lot more delicate than a power supply, like the oxygen sensor on a car?
 

Myrdhinn

Registered
Joined
Jun 25, 2002
What happens is a small current is sent through the probe.. this was a problem with many analog voltmeters however digital may not be prone to that behaviour. I'm just going by what an engineer I know that was with Bryston if anyone remembers Bryston stereo amps told me and that it is enough to damage delicate circuits. Maybe someone with more knowledge can clarify if it's true or not. I had no reason to disbelieve what I was told.


larrymoencurly said:
Could you explain how that feedback circuit works? I know from experience that having the voltmeter set to Ohms or Amps can casuse damage, :( but how can it cause damage while set to Volts, unless the circuitry is a lot more delicate than a power supply, like the oxygen sensor on a car?
 

Oklahoma Wolf

Senior Warranty Validity Sealed Stick Remover
Joined
Mar 18, 2003
Been an electronics tech for 13 years - yep, there is a small current from DMM's and voltmeters, but in the last 13 years I've never come across a circuit delicate enough to be damaged by my 3. Granted I don't own any cheap ones, but the circuitry in the usual SMPS (switch mode power supply) is not delicate enough to be damaged by any voltmeter or DMM just from using it to read the voltages at the outputs. The worst that'll happen is you won't get accurate results with a computer PSU unloaded.

I do know Bryston from my pro audio years - some of the best amplifiers on the planet, and I'm inclined to believe what any of their engineers tells me ;)
 

orion25

Folding in memory of my dads, Tim B. & Mike B.
Joined
Nov 22, 2002
Location
Alabama
nerdlogic said:
One way is to check your rails and see how much they are fluctuating.

How do you do this? With a Multimeter or with a program, such as MBM?
 

Stedeman

The Half Asleep Member
Joined
Aug 29, 2002
Location
Lewiston Maine
MBM is a SMART program and will give you all the voltage reading on your monitor you can find other SMART programs online what your looking for is spikes up and down and also out of spec readings
also another major and most over looked of problems is corrupt data if you get spikes it can cause memory faults that can go unseen a inline line protector / conditioner can also help as will UPS in some cases
 

Oklahoma Wolf

Senior Warranty Validity Sealed Stick Remover
Joined
Mar 18, 2003
Use a multimeter to find out conclusively what the PSU is doing - readings from MBM or the BIOS are typically reported after the board's regulation circuitry has a chance to alter them a bit. My own motherboard reports a terrible 5v (fluctuates from 4.88 to 4.98 at the worst times) via MBM when overclocking, but when measured with a DMM the 5v is fine (5.07 - no fluctuating at all).