Reterminating wall wart

mattmcl · 15th December 2009, 03:51 AM

I'm working on my first project, so this is a very nooby question but I want to be sure I understand.

I have a center positive wall wart which I need to reterminate. The positive wire is marked, so I can easily cut the old terminal off and resolder the new one on. What is the best way to test it? I know I can plug it in and measure the current with my multimeter, but how do I test to make sure I have center positive?

(This is somewhat theoretical, because I can be pretty darn sure to solder the positive wire in the center, but I want to understand what I'm doing.)

coolbeer · 15th December 2009, 05:27 AM

Uhm, what is there to understand?
If you have a DC wall-wart you can just switch the wires, or if you like to do it complicated, you can cut the wire, use the ohm or beeper mode on the multimeter(asuming it has one) and find the center-pin wire, then mesure where the positive lead is and connect the dots from there.

Unless I misunderstood you of course. Just try not to electrocute yourself(irony, I doubt it's even possible unless you really get creative

).

es44 · 15th December 2009, 06:53 AM

Quote:

Originally Posted by mattmcl

I know I can plug it in and measure the current with my multimeter, but how do I test to make sure I have center positive?

(This is somewhat theoretical, because I can be pretty darn sure to solder the positive wire in the center, but I want to understand what I'm doing.)

Don't measure the current, better measure the voltage. If you really want to understand what you are doing, please learn the difference of these.

Best regards
Ebbe

mattmcl · 15th December 2009, 03:12 PM

Quote:

Originally Posted by coolbeer

Uhm, what is there to understand?

I was wondering how I would test for center positive if I didn't know which wire was positive? That's what I meant by theoretical.

MJL21193 · 15th December 2009, 03:17 PM

You mention that you have a multimeter. Did you notice what colour the probes are? One is positive (red) and the other is negative (black). If you connect the red probe to the positive and the black probe to the negative, you will get a positive reading.
This is SO basic.
Seriously.

454Casull · 15th December 2009, 06:10 PM

If you're going to be working with electronics, perhaps a refresher course in electricity is in order.

Jason · 15th December 2009, 11:33 PM

When you can write a whole page essay about how electron flow is taught back to front at school, this is hardly a stupid question. http://www.eskimo.com/~billb/amateur/elecdir.html - should you connect a multimeter black to red, or black to black? If you've never done it before, how would you know? Shudder to think you might politely ask on a forum instead of crossing your fingers and hoping for the best and having enough money to buy it all again if you screw it up.

Matt welcome to the forum, and my sincere apologies - we have some people here that forget what it was like to first pick up a soldering iron with a sense of wonder and curiosity.

If we can't make newbies feel welcome here there is a serious problem - this forum was set up specifically to help newcomers bridge the gap between want and have.

jleaman · 15th December 2009, 11:50 PM

Quote:

Originally Posted by Jason

When you can write a whole page essay about how electron flow is taught back to front at school, this is hardly a stupid question. http://www.eskimo.com/~billb/amateur/elecdir.html - should you connect a multimeter black to red, or black to black? If you've never done it before, how would you know? Shudder to think you might politely ask on a forum instead of crossing your fingers and hoping for the best and having enough money to buy it all again if you screw it up.

Matt welcome to the forum, and my sincere apologies - we have some people here that forget what it was like to first pick up a soldering iron with a sense of wonder and curiosity.

If we can't make newbies feel welcome here there is a serious problem - this forum was set up specifically to help newcomers bridge the gap between want and have.

I guess if you look at it that way, however what he asked wasn't even related to audio, this is diyaudio right ?

ANYWAYS! it's a simple thing to do, its just as easy to unplug a cord from the wall and flip it over and plug it back in, you match wire for wire, using your meter to check polarity after, and bing its done.

Jason · 16th December 2009, 12:16 AM

Hi Jason. Matt said he's working on his first project. Yes, could be a motorized alligator project. Probably is an audio project. But it doesn't matter anyway. I think the point is that it's best to never assume and be as friendly as possible to people sticking their neck out to ask what to most of the members here are simple questions though

MJL21193 · 16th December 2009, 12:20 AM

Matt I apologize for being a bit snide. Like Jason says, we forget about our own humble beginnings sometimes.
Have fun.

15th December 2009, 03:51 AM	#1
mattmcl diyAudio Member Join Date: Apr 2009	Reterminating wall wart I'm working on my first project, so this is a very nooby question but I want to be sure I understand. I have a center positive wall wart which I need to reterminate. The positive wire is marked, so I can easily cut the old terminal off and resolder the new one on. What is the best way to test it? I know I can plug it in and measure the current with my multimeter, but how do I test to make sure I have center positive? (This is somewhat theoretical, because I can be pretty darn sure to solder the positive wire in the center, but I want to understand what I'm doing.)

15th December 2009, 06:10 PM	#6
454Casull diyAudio Member Join Date: Jan 2004 Location: Toronto, ON, Canada	If you're going to be working with electronics, perhaps a refresher course in electricity is in order. __________________ Building a 2.1 system out of a 3/4"x4'x8' sheet

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15th December 2009, 05:27 AM	#2
coolbeer diyAudio Member Join Date: Nov 2009	Uhm, what is there to understand? If you have a DC wall-wart you can just switch the wires, or if you like to do it complicated, you can cut the wire, use the ohm or beeper mode on the multimeter(asuming it has one) and find the center-pin wire, then mesure where the positive lead is and connect the dots from there. Unless I misunderstood you of course. Just try not to electrocute yourself(irony, I doubt it's even possible unless you really get creative ).

15th December 2009, 03:17 PM	#5
MJL21193 Account disabled at member's request Join Date: Mar 2007	You mention that you have a multimeter. Did you notice what colour the probes are? One is positive (red) and the other is negative (black). If you connect the red probe to the positive and the black probe to the negative, you will get a positive reading. This is SO basic. Seriously.

15th December 2009, 11:33 PM	#7
Jason :) diyAudio Administrator Join Date: Oct 2000 Location: Melbourne Blog Entries: 1	When you can write a whole page essay about how electron flow is taught back to front at school, this is hardly a stupid question. http://www.eskimo.com/~billb/amateur/elecdir.html - should you connect a multimeter black to red, or black to black? If you've never done it before, how would you know? Shudder to think you might politely ask on a forum instead of crossing your fingers and hoping for the best and having enough money to buy it all again if you screw it up. Matt welcome to the forum, and my sincere apologies - we have some people here that forget what it was like to first pick up a soldering iron with a sense of wonder and curiosity. If we can't make newbies feel welcome here there is a serious problem - this forum was set up specifically to help newcomers bridge the gap between want and have.

16th December 2009, 12:16 AM	#9
Jason :) diyAudio Administrator Join Date: Oct 2000 Location: Melbourne Blog Entries: 1	Hi Jason. Matt said he's working on his first project. Yes, could be a motorized alligator project. Probably is an audio project. But it doesn't matter anyway. I think the point is that it's best to never assume and be as friendly as possible to people sticking their neck out to ask what to most of the members here are simple questions though

16th December 2009, 12:20 AM	#10
MJL21193 Account disabled at member's request Join Date: Mar 2007	Matt I apologize for being a bit snide. Like Jason says, we forget about our own humble beginnings sometimes. Have fun.

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