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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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need help tracing power circuit on laptop
I'm attempting to fix a laptop for a friend. The power plug from the
power supply has been broken off and lost. Rather than spend $80 for a new supply I am trying to hard wire (via a quick disconnect) the power wire to the jack on the computer. I'm skilled with a soldering iron and I know I can make the necessary connections. My problem is I don't know how to find out which pins in the jack are positive, etc. The wire is a four conductor. Ground is easy to find by ohming to the case but I need to know how to trace the circuit for the other wires. Can someone please intruct me a bit on this? Many thanks. rrr |
#2
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need help tracing power circuit on laptop
I'm attempting to fix a laptop for a friend. The power plug from the
power supply has been broken off and lost. Rather than spend $80 for a new supply I am trying to hard wire (via a quick disconnect) the power wire to the jack on the computer. Forgive me for being overly harsh, but tell your friend to spend the $80 dollars for a replacement supply and, in the future, take better care of it. This is particularly true if the power adapter plug used more than two connections. If the only thing that's wrong is the adapter, then don't screw with the laptop and just replace the adapter. It may be expensive to buy the adapter, but it's even more expensive to replace the whole laptop if the modification is botched, especially if you don't have all the necessary tools to properly perform circuit level work on complex muti-layer boards. A modification which involves screwing with the main power feed in this manner does yield some serious safety concerns. If the repair causes loss, injury, or death, then it is YOU who could be liable simply because you performed a potentially unsafe alteration of the original UL/CSA listed design of the power feed circuit. You can also easily damage the laptop if you don't know what you are doing. Excessive heat from a soldering iron by itself is enough to easily cause damage to the mainboard and its components. Getting the mainboard out to service it can be a greatly convoluted task. You have to get a lot of things out of the way before you can remove the board to perform circuit level work. I should know as I had to deal with repairing a broken circuit trace for the adapter inlet on a Toshiba laptop. The whole thing had to be almost completely dismantled just to do that simple job. Besides, you aren't giving us any useful information about the laptop. Who made it and what is the model? To reiterate, just tell your friend to stop being a cheapskate and buy the replacement adapter, especially if there is nothing wrong with the laptop itself. This is the only fix that will be correct and the safest. - Reinhart |
#3
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need help tracing power circuit on laptop
Thanks for you advice. I'll expand a bit. First, I am quite competent at
such projects. I am an electronics technician and work with delicate circuits on a daily basis. That being said, I am confident I can fix this in a matter of minutes. I won't be soldering on the circuit board but rather on the pins in the jack. I have already dismantled the computer to the point where I can put a meter to the circuit board. What I need to do is trace the circuit and figure out which pins go to which wires on the power supply. If anyone can help me with this procedure I would be grateful. Per the risk of playing with a power feed: I work with dc systems everyday. I am aware that modifying a 12v source can cause damage to the equipment if the polarity is incorrect. Personal injury at such low amperage is not a risk at all. Obviously I want the polarity correct which is why I asking for help! Thanks in advance. rrr "LASERandDVDfan" wrote in message ... I'm attempting to fix a laptop for a friend. The power plug from the power supply has been broken off and lost. Rather than spend $80 for a new supply I am trying to hard wire (via a quick disconnect) the power wire to the jack on the computer. Forgive me for being overly harsh, but tell your friend to spend the $80 dollars for a replacement supply and, in the future, take better care of it. This is particularly true if the power adapter plug used more than two connections. If the only thing that's wrong is the adapter, then don't screw with the laptop and just replace the adapter. It may be expensive to buy the adapter, but it's even more expensive to replace the whole laptop if the modification is botched, especially if you don't have all the necessary tools to properly perform circuit level work on complex muti-layer boards. A modification which involves screwing with the main power feed in this manner does yield some serious safety concerns. If the repair causes loss, injury, or death, then it is YOU who could be liable simply because you performed a potentially unsafe alteration of the original UL/CSA listed design of the power feed circuit. You can also easily damage the laptop if you don't know what you are doing. Excessive heat from a soldering iron by itself is enough to easily cause damage to the mainboard and its components. Getting the mainboard out to service it can be a greatly convoluted task. You have to get a lot of things out of the way before you can remove the board to perform circuit level work. I should know as I had to deal with repairing a broken circuit trace for the adapter inlet on a Toshiba laptop. The whole thing had to be almost completely dismantled just to do that simple job. Besides, you aren't giving us any useful information about the laptop. Who made it and what is the model? To reiterate, just tell your friend to stop being a cheapskate and buy the replacement adapter, especially if there is nothing wrong with the laptop itself. This is the only fix that will be correct and the safest. - Reinhart |
#4
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need help tracing power circuit on laptop
Is this the seperate power adapter coming along with the laptop that plugs
into AC? What model is the laptop? |
#5
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need help tracing power circuit on laptop
The inner conductor may be positive or negative (most use a positive inner
conductor). If you get this one wrong, it will most likely do permanent damage to the laptop. Be extremely cautious!!!! Check and confirm before you start heating up the soldering iron |
#6
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need help tracing power circuit on laptop
The plug is not a normal round two conductor. If that were the case I would
go to Radio Shack and buy a replacement. As I stated it is a four conductor. There are four pins in the jack on the back of the laptop. The computer is a Prostar. I'm not sure of the model. Really it doesn't matter because what I need to know is how I can use a meter to trace the circuit to determine which pins go to which wires. The power wire has red, white, and black wires and a shield. I just need to know if there is a method of tracing the circuitry to determine which pin is which. Thanks again. "Sierra" wrote in message ... Is this the seperate power adapter coming along with the laptop that plugs into AC? What model is the laptop? |
#7
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need help tracing power circuit on laptop
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#8
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need help tracing power circuit on laptop
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