After years of lurking it's time for me to give something to the instructables community. I hope this can help!
By the way,
I WILL NOT TAKE ANY RESPONSABILITY for accidents or injuries occured trying or as a result of this instructables! DO IT AT YOUR OWN RISK!
and, if you want to give a try,
BE CAREFUL! Use glasses, gloves, mask and everything you need for YOUR SAFETY!
The power adapter of my HP dv6 notebook died a month ago.
Using a multitester I noticed that there was zero volt output. also putting my ear near the box I could ear a strange noise, some kind of syncopated twittering!
So I went to my computer shop and bought a new adapter, a universal one, but I wasn't completely satisfied with this solution:
- the new one has shorter cable, annoying!
- it doesn't connect very well, sometime I have to move the jack in and out until the notebook see it again;
- the new adapter has only 2 pins output while the HP one has 3 pins.. that third pin must be useful someway!
Enough! I've decided to open the black box to see If I can fix it!
Step 1: Tools
What I've used (and what maybe you need):
- Japanese sharp blade (x-acto knife should work well too)
- tin wire
- insulating tape
- duct tape
- soldering iron
- desoldering pump
- dremel with cutting tip
Step 2: Opening the adapter
The adapter did'nt work anymore. strange noise. using the multitester I noticed that the ground and Volt pin where short-circuited!
I supposed the problem should be in the cable. Time to open the black box!
Memo: Before going any further, unplug everything!
The box is made of two plastic shells fused together, there are no screws or clips, the only way to open it is cutting the junction line. Using dremel with cutting tip it take just 5 minutes. Luckly the inner circuit is protected by a metallic shell, so don't be too worried to cut something inside, just take your time and be very careful near the input and output cable.
When you can see metal on all the sides, gently open the plastic shell. there is some glue to keep all together, but it will surrender soon.
Step 3: Unsoldering the cable
Before desoldering take note of how cable are connected to the pcb.
In my adapter there are 3 pins: GND (ground), ID (identification?) and VOUT (voltage output).
My output cable is coaxial and it is connected this way:
outer layer go to GND,
mid layer go to VOUT,
inner layer to ID.
TRIVIAL NOTE: Seems like the ID pin is used for some kind of communication between adapter and notebook.. It transmit a signal at lower tension so that notebook recognize the adapter as an original HP product!
Unsolder the cable one pin at a time, from outer to inner, using the unsoldering pump and helping yourself with tweezers.
If the industrial soldering doesn't want to melt use this trick: melt some of your toxic and full-of-lead soldering wire on it and heat with your soldering iron. This will mix the two kind of tin lowering the melting temperature.
Control with the multitester if the VOUT and GND pins are still short-circuited. I hope the answer is no :)
Maybe now you want to check if the adapter works well before proceding..
This method is dangerous so please skip this part if you don't feel like doing it and be very careful!
Put the metal box back in one of the plastic shell's halves in a way that it is insulated from your desk and everything else. Choose the best side to face you considering that you want to easily reach the pins with the INSULATED tips of your multitester. Without touching any part of the open adapter plug the input cable. All you have to do is touch VOUT and GND pin with multitester tips to check if there is a correct potential difference (of 19 Volt for mine adapter). Checked? Unplug!
Step 4: Reparing the cable
So you know there is a short-circuit somewhere in the cable.. but where?
The best way to proceed is to cut away the last part near the black box, right after that kind of black plastic spring that should help to preserve the cable from broking (..and always fail!).
If the problem is in the cable, you can be sure it's somewhere in that critical zone. Check with multitester if now is ok, or cut another few centimeters and test again.
Don't throw away the plastic spring! Try to remove the broken cable from inside the spring and to put back it around the remaining good cable. I've had to cut the spring in three part cause it was soldered to the cable, yet it has been still useful.
Once the spring is back around the cable, strip the wire one layer at time. Looking at pictures you can see that I cut the wire on the long way cause I reuse the plastic coating for insulation and strenght.
Twist together the wires of each layer and insulate with tape. Check to which pin each wire must go. Try to rearrange the three wires so that it'll be easy to solder back it on the adapter, then block everythig with tape.
Resolder the wires to the adapter, from inner to outer pin.
Step 5: Closing the box
Put back together the plastic shell and block it with duct tape. Be careful to not leave exposed any metal part.
You're done! Plug everything.. and cross your fingers.
Step 6: Happy ending!