Evaluate & Repair a Laptop

A friend loaned me his laptop to repair and/or diagnose. The laptop doesn’t power on.


Before attempting repair, some intelligence gathering is in order:

HP Pavilion dv5215us

DC adapter

DC Adapter specifications
HP Part# 380467-003
HP Spare 381090-001 HP-OK065B13 LF
in/out Voltage Current
input 100-240 VAC ~1.7A 50-60Hz
output 18.5 VDC 3.5A 63W

AC power cord (for DC adapter)


Isolation of the failed component is the next task. Given the complaint, failure in the following are possibilities:

  • AC power cord
  • DC adapter/cord assembly
  • laptop’s power jack
  • laptop power system
  • laptop battery (possibly shorted)
Action Observation
I verified the existence of the power problem by trying to start the computer with the included adapter. The computer failed to power up.

I noticed that the unloaded power adapter is cool to the touch. (Since adapters typically radiate waste energy as heat this could indicate a failure in the AC power cord or the adapter itself.)

I then began to isolate various components. Special thanks go to the friendly staff at the local Radio Shack, who provided the multimeter and the test power supply.
Multimeter readings were taken from the DC adapter. The AC power cable tested OK.
The DC adapter failed to deliver any power.
An aftermarket power adapter was connected.
  • fan started and then stopped
  • indicator LEDs lit up (and stayed lit)
  • no POST or video output on the LCD screen of any kind

A search determined two likely causes of the failed boot/video:

  • loose hardware component (typically RAM or hard drive)
  • bad motherboard


  • The AC power cord is OK.
  • The DC adapter/cord assembly has failed. (as suspected)

Data Recovery

There’s a possibility I will be unable to either determine the cause or find a solution to the laptop’s problems.

I plan to give my friend various options to recover their data.


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