Introduction: Diy USB Charger for Harmony 1000 Remote
Some time ago i got an old Logitech Harmony 1000 Remote but without a chargin cradle or an original battery. I found out, that an old battery from a Nokia Mobile would work to although the remote couldn't charge it, neither on the cradle nor via USB. So i built my own charger around a simple Li-ion charging IC from Maxim.
In various boards on the net i read, that some harmony remotes had problems to charge the battery after a while, this will fix this problem, too. (With some aditional steps)
Step 1: Gather the Materials and Build the Circuit
Step 2: Disassembling the Remote
First, we need to disassemble the remote. That's rather easy. Pull of the battery cover and take out the battery.
You will now see 3 screws, that need to be taken out (see red arrows)
Step 3: Go On
Now, turn over the remote so you can see the USB port. Pull out the little rubber to see it. Here is another screw, see the picture.
After you've unscrewed it, you can carefully open the remote. Start from the battery housing and smoothly pray it open.
You have to expand it from the lower side to the upper as there is a cable from the LCD screen to the PCB of the remote. See 2nd Picture.
After you've sucessfully opened it, lay it down to the table. Be carefull with the brown cable coming from the LCD screen. Don't damage it.
You'll see another 2 screws on the left that you need to take out.
On the lower right theres another brown cable for the keypad. (see red arrow) Gently push the white plastic of the jack in direction of the keypad. After it's a bit loose, you can simply, but carefully pull out the brown cable of the keypad.
Step 4: Loudspeaker and Power Cable
Now, you can lift the whole PCB a little bit. Under it on the left, there's the loudspeaker (red arrow). It is glued to the housing. I used a small screwdriver to pry it out. Best is, you put the screwdriver a little bit under it from where the 2 cables come and lift it up.
Next are the power cables for the charging dock. (blue arrow)
You could unsolder them, but i simply cut them as i didn't need them again.
After that, you can flip the circuit board over to the top so it lays on the LCD screen.
Carefully pull the cable out. Do this after you pulled a little bit on the brown plastic thing of the jack. (See 2nd picture)
Step 5: Looking for a Way to Power the Charger
After the last step, you can take out the whole PCB Board. Behind the USB jack there's a little white fuse, marked as "F1" (see red arrow). This is, where our charging circuit will get its power. Later, we will solder some cable from the right side of the fuse to the positive terminal of the chargin circuit.
On the next picture you'll see my finished circuit board with the MAX1555. You should try to get it as small as possible so it will fit into the remote.
To connect the charger there a small solder pads, mine aren't marked anyway. After you built it you should know where the positive and negative terminal from USB is, where to connect the battery and optional the charging indicator LED.
Now we have to find a location where we could place the circuit. See next step.
Step 6: Solder Time
On the first picture, you'll see where i put my circuit. I fixed it to the PCB using some hot glue. Be carefully not to use too much glue so the whole thing doesn't get to high.
Connect the positive supply terminal from your circuit to the fuse of the remote as described in last step.
The negative terminal goes to some ground point on the remote, i used the "V-" pad where the original chargin cradle was connected. You could use some other points, too, e.g. the gnd connection from the remote's usb jack.
Now to the charging output. If you look to the remote's pcb like in the picture there's the battery connector on the right. This has 3 golden contacts. The right one is GND, the middle one is for temperature sensing and the right one is the positive connection.
This one has to be connected to the chargers chargin output. ( green cable in 2nd picture)
I glued all cables to the pcb using some dots of hot glue to hold it in place. Be carefull not to accidantly short something.
Step 7: LED Charging Indicator (optional)
This step is optional, but i think rather useful.
The MAX1555 features an status output, where a led can be connected. (see the circuit)
I used a little orange smd led, that i glued on the front side next to the blue led for the "activities"- button of the remote. Mine's rather small, don't use to big ones in order to make the housing of the remote fit again.
On the 2nd picture you can again see how i connected all together.
Yours can look different depending of your charging circuit you built.
After you've double checked everything, you're almost finished.
Step 8: Connections for a Chargin Cradle (Optional)
If you want to charge the remote via an chargin cradle, you've to make one connection more. Connect the appropriate terminal for external chargers on your MAX1555 circuit (see circuit at sparkfun) to the positive conntact on the remotes housing (where "Ve+" ) was connected. Be sure, that the positive chargin conntact from the remotes' housing (on the lower side) doesn't have a connection to the remote's Circuit anymore. It should only have contact to the MAX1555 Charging circuit.
But be carefull: I dont know which voltage the original cradle gives out. The MAX1555 IC can only handle 5 to 7 Volts. If the output of the cradle is above 7 Volts, the carging IC will be damaged. If so you'll have to modify the cradle as well.
Step 9: Put It Together Back Again
After i wanted to put the remote together again, i noticed that with the circuit, the housing didn't fit anymore. On the back side of the case there're some plastic spacers. I simply cut the lower one a bit with a sharp knife, so everything would fit again.
Be carefull: Don't use too much preassure as the Screen and touchscreen could be damaged.
If everything fits, put the remote in reverse order together back again.
Step 10: Put in the New Battery and Test It Out
As you can see, the battey from the mobile phone is a little bit smaller as the original one, so i used some cardboard to make it fit.
Put in the battery, the remote will then hopefully power on. Put in a USB cable to the remote an the other end to your computer or perhaps some USB charger for mp3 players you've laying around.
If you built the circuit with led status indicator, the led should now light up.
In the second picture you can see mine. The orange LED is a bit dark, but you can see it. After fully charged, the LED will go off.
Please notice: I'm not responsible for any damage to your remotes, computers or yourself, do this at your own risk.
I hope you'll liked my 1. Instructable !!!
Greetings from Germany,