Jump to content


 


Register a free account to unlock additional features at BleepingComputer.com
Welcome to BleepingComputer, a free community where people like yourself come together to discuss and learn how to use their computers. Using the site is easy and fun. As a guest, you can browse and view the various discussions in the forums, but can not create a new topic or reply to an existing one unless you are logged in. Other benefits of registering an account are subscribing to topics and forums, creating a blog, and having no ads shown anywhere on the site.


Click here to Register a free account now! or read our Welcome Guide to learn how to use this site.

Photo

PSU (power supply) actual voltage reading issue


  • Please log in to reply
11 replies to this topic

#1 4as_pc

4as_pc

  • Members
  • 4 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:04:45 PM

Posted 30 May 2016 - 07:50 PM

I am troubleshooting my ATX power supply unit, the standard voltage for red is +5.0 v but using my multimeter actual reading is 10.8 v, for orange pin standard is (+3.5v) actual reading is 6.9v while for the yellow pin standard is 12v my actual reading is 25.4v . is there any problem with my multimeter or with my PSU (power supply unit) .. please help me.. thanks.. :unsure:



BC AdBot (Login to Remove)

 


#2 TheTripleDeuce

TheTripleDeuce

  • Members
  • 275 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Canada EH!
  • Local time:05:45 AM

Posted 30 May 2016 - 08:17 PM

it sounds like your PSU is fine TBH it is almost like your multimeter is too sensitive as its is returning almost double of what the actual value should be, try this site for how to check multimeter accuracy

http://www.designworldonline.com/how-to-determine-digital-multimeter-accuracy

 

also just curious why your testing your PSU


Edited by TheTripleDeuce, 30 May 2016 - 08:18 PM.


#3 4as_pc

4as_pc
  • Topic Starter

  • Members
  • 4 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:04:45 PM

Posted 30 May 2016 - 08:40 PM

i am testing my PSU because my PC has power but no display on screen no i don't hear  POST beeps. but but when i tried to restart the PC the CPU fan seems like it rotates double the speed and i can really hear it sounds then that's the time my PC begins to display on screen and it will suddenly stops then the screen will be black then it'll not boot anymore. thanks for your prompt reply....



#4 TheTripleDeuce

TheTripleDeuce

  • Members
  • 275 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Canada EH!
  • Local time:05:45 AM

Posted 30 May 2016 - 08:48 PM

does it post at all on display? if im correct it should work fine if the PSU is outputting to much power via the leads(I could be incorrect if so please correct me someone), however it isn't good for the system for long term use, is your display built into your motherboard or a replaceable part? do any hard drives spool up as well as the heatsink fan?



#5 Platypus

Platypus

  • Moderator
  • 13,676 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Australia
  • Local time:06:45 PM

Posted 30 May 2016 - 09:25 PM

I suggest before doing anything else you need to confirm the correct operation of your meter, say by measuring something of certain voltage such as the 12V battery in a car. If the PSU in the computer was producing those voltages, we would expect it to destroy everything attached to it.

Top 5 things that never get done:

1.


#6 4as_pc

4as_pc
  • Topic Starter

  • Members
  • 4 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:04:45 PM

Posted 30 May 2016 - 10:24 PM

does it post at all on display? if im correct it should work fine if the PSU is outputting to much power via the leads(I could be incorrect if so please correct me someone), however it isn't good for the system for long term use, is your display built into your motherboard or a replaceable part? do any hard drives spool up as well as the heatsink fan?

 - yes, but it's intermittent that's why I dcided to troubleshoot my PSU, yes all are built in on the system board, actually my  the unit is HP Pavilion slimline i3, and the power supply's part # is HP P/N:504965-001, no hard drive doesn't spool up except for the heatsink as I mentioned earlier. I'm really having issue on the reading of the voltage PINS output voltage on my DMM, actually I already try to test it on my 12V DC motorcycle battery it's fine it shows 13 VDC also with the 1.5 V AAA remote control battery it displays the actual rated std voltage which is 1.5 v. I just bought this DMM yesterday it's NEWSTAR UT-33D..  



#7 4as_pc

4as_pc
  • Topic Starter

  • Members
  • 4 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:04:45 PM

Posted 30 May 2016 - 10:29 PM

I suggest before doing anything else you need to confirm the correct operation of your meter, say by measuring something of certain voltage such as the 12V battery in a car. If the PSU in the computer was producing those voltages, we would expect it to destroy everything attached to it.

- Yes sir, it works fine with my motorcycle battery 12V DC. I also tried to use it with the AAA size 1.5 V DC it works fine same as the rated voltage,  but with the PSU 24 pin, the reading is doubled.. just one more thing to ask ?are all PSU auto volt? that's why my output voltage reading is doubled? please enlighten me on this? thank you.



#8 Platypus

Platypus

  • Moderator
  • 13,676 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Australia
  • Local time:06:45 PM

Posted 30 May 2016 - 10:56 PM

All PSUs will automatically produce the correct output voltages unless faulty, as this is critical for operation of a computer. Not all PSUs are automatic for input voltage selection, some have a manual switch to choose between 110-120V or 220-240V mains, however that will not change output voltage but can damage the PSU if set wrongly.

I would not proceed with fault-finding using that PSU. For safety of other components, further diagnosis should be done using a known good PSU.

Top 5 things that never get done:

1.


#9 mjd420nova

mjd420nova

  • Members
  • 1,677 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:01:45 AM

Posted 31 May 2016 - 08:27 PM

The other possibility is that you have chosen the wrong point for the negative or black lead from the meter.  Also, the selection of input voltage 120 V or 220 V would result in half the voltage and not double is the 220 v position is selected.


Edited by mjd420nova, 31 May 2016 - 08:28 PM.


#10 Platypus

Platypus

  • Moderator
  • 13,676 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Australia
  • Local time:06:45 PM

Posted 31 May 2016 - 10:17 PM

The other possibility is that you have chosen the wrong point for the negative or black lead from the meter.


I wondered about that too, but doing that should produce a constant offset voltage, not a multiplication.

Also, the selection of input voltage 120 V or 220 V would result in half the voltage and not double is the 220 v position is selected.


The output is regulated without reference to the input, so the output voltages wouldn't simply halve. Of course you're right that it wouldn't go up!

Actually all the switch does when a PSU has one, is choose whether the input reservoir capacitance across the rectified mains is a single capacitor for 120V or two capacitors in series for 240V.

Top 5 things that never get done:

1.


#11 deronmoped

deronmoped

  • Members
  • 12 posts
  • OFFLINE
  •  
  • Local time:01:45 AM

Posted 02 June 2016 - 01:55 PM

Measuring the voltage on a PS can be load dependent. Measure the voltages when the PS is hooked to the load you intend to use it on.



#12 DavisMcCarn

DavisMcCarn

  • Members
  • 731 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:04:45 AM

Posted 02 June 2016 - 04:51 PM

What is the complete model number of the HP or its P/N which is on the same sticker as the serial number?
Computer dinosaur, servicing PC's since 1976




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users