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I bought my mom, who lives in India, a Panasonic toughbook CF-W8 a couple of years back. A few days back, due to some voltage fluctuations, her adapter/power cord blew out (along with a whole bunch or other stuff in the house).

Her laptop is fine and she has used it a bit with whatever power it has remaining. I have bought a new adapter for her over eBay and it should reach her in 3-4 weeks. In the mean time my dad asked a friend of a friend to fix the adapter and now some random person has "fixed" the adapter.

Now I am a bit nervous about the state of the adaptor and have asked my mom not to use it since i don't want her to damage her laptop.

I was wondering if there is any way to test if the "fixed" adapter is safe for use? and also, I just want to confirm that it is indeed dangerous to actually try the adapter on the laptop since I have no idea if the person who fixed it knew what he was doing.

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closed as off topic by Leon Heller, Dave Tweed, Nick Alexeev, Brian Carlton, Olin Lathrop Nov 6 '12 at 0:15

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    \$\begingroup\$ MUST have isolation between the input and output. Must not be a low resistance connection between either input pin and either output terminal. \$\endgroup\$ – Russell McMahon Nov 4 '12 at 11:03
  • \$\begingroup\$ @RussellMcMahon .. I'm sorry but I didn't understand a word of that. \$\endgroup\$ – Amatya Nov 4 '12 at 11:44
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    \$\begingroup\$ (2) Read faceplate voltage. Often 19V but may be lower. Read current rating. Calculate R = V I eg say it was 19V and 5A. R = 19/5 = 3 8 Ohms. Make a resistor of about right or slightly higher resistance than calculated and at coccet wattage. Nichrome wire. multiple power resistors etc. Load output with resistor and leave running for several hours. Vout should be about at rated spec and should stay at that voltage more or less. That's afairly tough test - you could aim for say 2/3 rated current. \$\endgroup\$ – Russell McMahon Nov 4 '12 at 11:50
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The advice you already got to use a voltmeter is good.

Check that the DC voltage is correct and also make sure there isn't a significant AC component to the voltage (for reference, my third party laptop power adapter has just under 3 volts AC unloaded). You are correct that the repaired adapter could be dangerous. It's likely only dangerous in another fault condition though. I've seen people short blown fuses with a wire as opposed to replacing them. This could cause damage to the laptop or, in the worst case, start a fire were there to be another fluctuation.

Personally, if the voltage matches up, I wouldn't be too uncomfortable using the repaired adapter. Still, it might be good to get a hold of the person and ask them how they fixed it.

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