Laptop power supply puts out less voltage than rated for


My son's Asus G71GX-RX05 suddenly will not start anymore, and it's completely dead, no lights, noises, etc. We tried taking out the battery and just using the AC power supply, but no go. As part of initial troubleshooting, I put a multimeter on the power supply when it was just plugged into the wall but not the laptop. It is rated for 19.5V, but I am only reading 19.22V. I tried the same thing on another power supply I know is good that is also rated for 19.5V (but is for a different laptop), and the measured output was 19.55V. From my understanding, if you measure a power supply output when there is no draw on it, you should at least measure the rated output if not more. question is this enough to cause the symptoms we're seeing? I didn't want to drop the $20 or so for a new one until checking to see if this is really a problem - i.e. 19.5V rated vs 19.22V with no draw on it.

Thanks in advance.
4 answers Last reply
More about laptop power supply puts voltage rated
  1. Assuming there is still some charge left in the battery, the laptop should power up on battery power alone, regardless of what's wrong (if anything) with the a/c adapter.

    So either the battery charge state has fallen too low to power up the laptop, or there's a more serious problem with the laptop.
  2. Thanks for the reply. The laptop is completely dead on battery power alone as well. However, I don't know if the battery is discharged or not and am not sure how to test that.

    Any opinion if the output of the AC transformer is inadequate to power up the laptop?
  3. Try to check the voltage when your transformer is plug to your laptop, push power, if the voltage is around 19 volts, the transformer maybe good, it all depends if the laptop draw some current from the transformer.
  4. Thanks for the help. We disassembled the laptop, and it turns out there was a metal clip that had fallen out of another spot on the laptop that was grounding out the power as it came into the motherboard. There are about 10 of these clips surrounding the access plates on the bottom of the laptop and they seem unimportant (just affixed to the plastic). Since 3 or 4 had already fallen out and were rattling around the inside of the laptop, we just removed them all. Upon reassembling the laptop, everything worked great. So, two lessons:

    1) The output of the power supply when plugged into the wall but not the laptop can be less than the rated output and that is fine

    2) If your laptop doesn't work, diassemble it and have a look. Something might catch your eye (like a wayward metal clip wedged in a bad spot).

    So this is solved.
Ask a new question

Read More

Laptops Power Supplies