Another use for the Kill-a-Watt...
 

Yesterday, my best friend Allie Moore asked me if I could fix her computer. Of course, I accepted the offer. The computer would not run on AC power, but it will charge (slowly) if it is turned off.

The tools I brought are a Kill-a-Watt, a multimeter, a pair of "swiss army pliers", a set of screwdrivers, some soldering equipment, some electrical tape, and a 25w, 8.2 ohm resistor.

The problem was a bad connection in the plug. How I noticed it was that the Kill-a-Watt was always showing very low power draw at all times. Oddly enough, the multimeter showed full voltage at the plug. Out of curiosity, I decided to try load testing with the resistor. The voltage dropped by about half and the plug immediately got hot. I used the pliers to cut back the plug, exposing the connections. I resoldered them and it worked perfectly, after which I insulated the connections with electrical tape. I used the Kill-a-Watt to confirm that the power supply was indeed working.

I bet many students were wondering what was going on when I was sitting with a pretty girl, in the middle of the study lounge taking apart a laptop, using some unusual tools, and saying a lot of technical terms. Knowing how I am well known for my engineering, many probably thought I was training her to be a computer technician or something. :)

She also had another power supply that was broken for a long time. I currently have it on my desk. It appears completely dead as far as the output goes, but an AM radio shows that something is still working inside and the Kill-a-Watt indicates an unsteady current draw. I have just opened it and noticed some bad capacitors. Sometime later, I will replace those capacitors and test to see if it works.

Nice job. I'm surprised the plug didn't get warm while it was plugged into the laptop. Not enough current draw I guess.

Nothing quite like helping out pretty girls in the sight of other pretty girls. :thumbup:

Seriously, nice job on the diagnose, most don't have the wherewithal to do it and trash the item and buy a replacement. So much cheaper most times to fix it yourself.

My brother tells me he has two computers, doesn;t know what they need. I drive 290 miles round trip, I get to keep one.
one is a hp6735 attempting to run on 100w. <8k hours runtime since the year 2001, never updated, still had win me...
no problem. I ran a p2 for web chores and knew the celeron 633 with a 10 dollar ebay rage 128 GL vid card, and it would do just fine as backup. It ran, I am here with it.

The other computer, he talked as if was nice. for some reason the 2.7ghz celeron had a missing pin and many were bent.I asked him how, and he said his neighbors kid picked it up and thew it against the wall with the heavy heatsink still stuck to it.

WTF?! :confused:


Been there done this, only 130nm/90nm is getting pretty freakin small for eyeballs and a little flat edge to straighten them. so I get the cpu squared away, drop a jumper in the 478 socket for the missing pin... the ide popped right before my very eyes...out loud.
He tells me he grabbed the hi-pro power and it squished its covering against the heatsink... he got 120v,(electrocuted himself). just like the whole computer apparently. So far , it has shown to take:
the rom,
the hard drive,
the hard drive ribben,
the cpu,
a stick of infineon ram,
and the motherboard...
and the battery is hopelessly no go (very odd)
all at the same freakin time. The odds are greater to get zapped by a psu... :rolleyes:

I'd rather fix a pretty girls computer..

I just got the other power supply fixed. Just a bad capacitor and I reflowed some connections that look like they might be falling apart. Now to load test it and then get some tape to keep the case closed. (Not glue so it would be easy to open if it breaks again.) I plan to send it back tomorrow.

BTW, I would not recommend HP stuff anymore. The power supply appears to be lesser quality than some other ones I have worked with. It was not the first time I had issues with HP, either. In one of my engineering labs, the HP oscilloscopes would intermittently fail to display the cursors. Very annoying when I'm trying to find the actual voltages. The "fix" is to rapidly cycle through several menus, which somehow clears the bug. And when I'm looking for deals on oscilloscopes, I would mainly look for Tektronix.