loading
I use a Sony MP3 CD player to listen to Podcasts and to my audio Bible, also MP3. I have NiCad AA batteries in it. They were free. But, if I need to charge them, I must open the lid to get at the battery compartment. That causes my place in my audio program to be lost. I wanted to be able to charge the NiCad batteries without losing my place.

Step 1: Open the Player

The red arrow points to the door of the battery compartment. The red squares show the locations of the screws that hold the player together. As you know, avoid touching the reader lens with your fingers. The lime green arrow points to the power jack.

Remove the screws. Pry the case of the player open.

Step 2: The Goal

The photo shows the circuit board. The black screwdriver bit points toward the power jack (yellow plastic) and a shunt I soldered between two points on the circuit board.

The player's power jack is designed so that the connection to the batteries is broken and only external power flows to the player circuitry when the power supply's plug is in place. In time the power jack's internal connections loosened. The least movement while listening often caused the power connection from the external supply to be lost. That also caused my place in my audio program to be lost. It was frustrating.

The solution was to use the external power jack and supply to feed charging current to the batteries. Making that possible meant adding a shunt so the batteries are not locked out when the external power supply's jack is inserted. See the next steps for the circuitry and how to know which solder connections to shunt.

Step 3: How the Power Jack Works - Part 1

Below is a pictorial schematic on the player's jack circuitry. One cell is shown, but there are actually two. The red lines and the red center post are electrically positive. The black lines are electrically negative.

Here you see the circuit as it works without the external power plug inserted into the player. Note the closed contacts that are part of the negative side of the female power receptacle.

Step 4: How the Power Jack Works - Part 2

Here you see the power jack inserted into the player. Notice that the contact points have been pushed open by the power plug.

The power jack is center point positive. The inside of the jack is mostly plastic. But, there is a curved piece of metal that makes contact with the external part of the male power plug. See the black curved line. When the male plug is in the player's power jack, the battery is cut out of the circuit.

Step 5: The Shunt

The plan is to add a shunt (azure blue line) to keep the battery from being locked out of the circuit.

After the player's circuit board is out of the player, use your ohmmeter to get a clear understanding of which solder joints go to which conductors in the player's power jack. Determine which solder joint on the circuit board connects directly to the negative terminal in the battery compartment. Which terminal connects to the negative terminal in the battery compartment when the male power jack is not inserted into the player, but is not connected when the plug is inserted? Connect it with a shunt to the solder joint always connected directly to the negative terminal in the battery compartment.

When soldering on the circuit board, be careful that no solder forms an unintended bridge to another solder joint and shorts something out.

My charging time is about 45 minutes. The batteries go down quickly when the number of bars in the power indicator on the display get below half full. The batteries I use were already used in another application, so I do not worry too much about overcharging them. I can get more.

It is possible to listen to the player while the batteries are charging, too.
little bit to much work and to complicated just to prevent you from losing your place...
Thank you for reading this Instructable. I think this modification took me between 30 and 60 minutes from start to finish. That included figuring it all out the first time. I actually have two of these players. What I learned on the first one made things go more quickly on the second one. Just making the modification was not too complicated. It gets complicated when you try to explain it to someone else in detail with graphics for an Instructable. But, once you understand it and how to do it, you can make a similar modification on other devices, which I did much earlier on a battery powered children's game when our kids were small.
I have to respect someone who sticks with a system. Although it does work; I do prefer a zune. They can be charged on car, solar, or computer, or plugin to wall. You do not need to plug in for new content (wireless sync); and you don't lose your place when you charge. Still, kudos on the 'ible. mp3 disc players are great for most things.
My daughter has a Zune, but she also lives several states away from me and I have never actually seen her Zune. I almost wish I had a friend with a Zune so he could show me what it will do and how to operate it. In that event I might want one. I do have a SanDisk 2 GB player and use it, but I also still like the disc players for their utter simplicity.
how is a disk player more simple than an mp3 player?  they work the same but you dont have to switch disks ..................mind boggling
 I now have a couple of small (1 GB and 2 GB) players, too.  The CD/MP3 players never play my downloaded audio Bible files in the wrong order, but the little MP3 players have done that until I manually added an MP3 tag to each file.  The screen on my CD/MP3 player gives me far more information about what is playing and in several formats.  My MP3 players do not do that.  The CD/MP3 players are simple "on" and "off."  If I push the wrong part of the control ring on one MP3 player I can end up in a sub-menu and it takes a couple of tries to get back out to the main menu.  If I load a combination of genres onto my MP3 players, I have little control over keeping them separate from one another and cannot bookmark them, but I can find any file in a very simple and logical fashion with my CD/MP3 player.  Let your mind not be boggled!  
wow...i did this when i was 5 years old,never thought someone gonna put this up,so simple....Anyway,good job...
or you could recycle the entire thing and just go buy a used 4-60 gb ipod... for about 20-40 bucks.
I made a decision about four years ago that my player of preference would be an MP3 disc player. The life expectancy of an iPod with internal hard drive is about four years. If they do not have hard drive problems by then, they almost certainly have battery problems. My player is still going strong after four years. I do not need to connect it to a computer to change its contents, just slap in a new disc. The NiCads and my modification make it even more useful. If my disc player breaks or is lost or stolen, I can get a new one for less than $60. If you like an iPod, good for you. I have not been that impressed with what I know about them from watching and listening to people who have them.
I'm not an iPod fan, but I've owned a few, you are right the batteries don't last very long if you do not take care of them, but if you do they can easily last more than four years, in regard to the hard drive, if it dies just replace it with a flash module, that will also be the time that you would replace the battery. I believe there is an Instructable for a 32 or 16gb ipod mini... that's the one I used. Also, the small zunes, and the ipod nanos all have flash memory that they say is able to last up to 20 years. Finally, in regard to the having to plug it into your computer to charge it, you could buy a wall charger, but how much time do you really spend at your computer a day burning podcasts to disks? I'm sure its nearly the same amount of time you could be syncing your player and charging it.
Thank you for the information about converting an iPod to a flash module. I will look for that Instructable. I really spend very little time burning discs for my player. As I mentioned in the Instructable, I use one of my players for listening to the Bible. I have been using the same two discs daily for four years. I do not use digital players for music. I also download Podcasts. I find I most often listen to those in the car. I simply use iTunes to convert MP3 files to WAV discs. If I upgrade anything, I would go for a car stereo with built-in MP3 on the CD drive. The Podcasts are in German so I can practice the language. A couple of times a year I may burn half-a-dozen new discs. I do not need to burn more discs because I can listen to the same one over and over until I understand every word clearly. Every so often I need to send e-mail to someone or some business in Germany. The recipients are often impressed that a citizen of the USA does as well as I apparently do in German. I am always surprised when a German compliments me on my abilities in the German language. I did once buy a 1 GB Sandisk Sansa player, but I have not used it nearly as much as I thought I would. The MP3 disc players are my tried and true workhorses.

About This Instructable

4,447views

4favorites

License:

Bio: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying ... More »
More by Phil B:Easy Monitor for NordicTrack Skier Uses for Spent K-Cups Make a Conduit Bender 
Add instructable to: