Li-Po battery charger replacement for damaged Logitech K830 keyboard

[M.A.L.S]

Hi all,

Just wanted to see if I can get some advise on fixing my Logitech K830 keyboard. Unfortunately the micro USB port has been ripped off taking the traces with it so I can no longer use the internal charge circuitry to charge it. The keyboard still works fine but it obviously won’t charge.

What specifications do you have to match up to safely charge a Li-pro battery? The battery in my K830 is 1100mAh 3.7V 4.07Wh. Maximum voltage charge rate is 4.2v.
Link showing a tear down of my keyboard: https://fccid.io/JNZYR0047B/Internal-Photos/Internal-Photos-2557153]  [url]https://fccid.io/JNZYR0047B/Internal-Photos/Internal-Photos-2557153 [/url]

I was thinking of getting something like the below linked product so I can connect the battery to that and charge it whenever needed.
https://www.jaycar.com.au/power-pack-for-raspberry-pi-with-li-ion-battery/p/XC9060?pos=12&queryId=abdeae415821a560f7f0a81d8cbb0d4f&sort=Li-relevance]  [url]https://www.jaycar.com.au/power-pack-for-raspberry-pi-with-li-ion-battery/p/XC9060?pos=12&queryId=abdeae415821a560f7f0a81d8cbb0d4f&sort=Li-relevance [/url]

The above link comes with a bigger battery too, and same output voltage as my battery so I should be able to use that correct? My battery uses a 3 pin plug to connect to a connector on the board, so I was thinking of getting a extension cable and plugging that into the board and having the other end hanging out of the case to make it easy to recharge.

Thanks for your assistance let me know if you need any more deets.

[m3vuv]

why not use a tp4056?

[M.A.L.S]

Because that has a 5v output, this battery has a max charge voltage of 4.2.

[all_repair]

Can't see your links.  Getting "about:blank#blocked". 
Search for "18650 UPS", see if the PCB can fit inside your keyboard.

I am having some fun with this module.  The output can change by changing a resistance.  So I have modified one with a variable preset, and using it as a quck and easy supply for testing.

[sleemanj]

Because that has a 5v output

No it doesn't.

[M.A.L.S]

Than why do all the listing pages say it does?

[gabiz_ro]

Still damaged USB connector,you may still can use internal charger circuit.
But internal photos from fccid aren't clear enough.
Take some good photos of that area and maybe we can identify where to apply 5V via another plug connector.

[sleemanj]

Than why do all the listing pages say it does?

Because they are wrong.

RTFM

https://www.google.com/url?sa=t&source=web&rct=j&url=https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf&ved=2ahUKEwiBwovX1N_yAhXCWisKHe4LCGYQFnoECAMQAQ&usg=AOvVaw2gHFLyoq4KAKjtj1Tkmq0z

If a listing says 5v, either they are talking about the input voltage, or they are just clueless resellers who don't know about what they are selling.  Read the specifications in the description of your board to determine which is the correct answer for your particular seller.

[m3vuv]

You are wrong there,,i have a few of them,none output 5v,all of mine are outputting about 4.1 volts.,if i remember the input voltage is from 5 to 8 volts.

[M.A.L.S]

Still damaged USB connector,you may still can use internal charger circuit.
But internal photos from fccid aren't clear enough.
Take some good photos of that area and maybe we can identify where to apply 5V via another plug connector.

https://ibb.co/KyfwCKp top of board

https://ibb.co/5F0g5SK top of board zoomed into where micro b connector was.

https://ibb.co/g66HZWc bottom of board.

Thanks please see links above since imbedded did not work last time.  Top left corner is where the micro b plug was and there’s where the pads have been ripped pff. It’s hard to see but it looks like there’s two big pads which I believe are the mounting points for the connector. The pin pads are completely gone but I can see two traces on the right corner of where the plug will be and they go to the white rectangle mask looks like they go underneath that and to the interstates board which I believe is the Bluetooth controller.

What’s the connector called for the battery this uses? I’ve found tons of USB charge boards like the tp4056 like mentioned above but none of them have the battery connector, they all require you to solder the battery to then. I need something that has the same battery connector so I can simply disconnect it from the keyboard and charge it whenever needed.

Lastly for slide switches can they be replaced with rocker switches? Trying to put the board back together last night I snapped the slide portion of the switch. I’d be nice if I could replace it with something like a rocker switch something less puny and designed to break if you look at it from the wrong angle.


Thanks.

[NiHaoMike]

That large trace is the 5V input, negative is ground. Should be easy to solder a replacement connector in place. There are even micro USB connectors that only have power and ground pins to greatly reduce the precision needed.

[M.A.L.S]

That large trace is the 5V input, negative is ground. Should be easy to solder a replacement connector in place. There are even micro USB connectors that only have power and ground pins to greatly reduce the precision needed.

By large trace which one do you mean? There’s two of the same size coming out from the anchor pads where the port use to sit. I assume one of those is ground and one is 5v but scratching them back and continuity testing to the battery connector to try and find what is 5v did not reveal anything. I think those traces go through a via to the bottom of the board and few a few other things.

[gabiz_ro]

On that header on bottom of PCB you have VUSB and GND,you may apply 5V from external power source and see if charging.
If not,VUSB maybe not really routed to that header or for charging you need short or something on USB dataa+ and - lines.

Looking again at photos looks like U1 near battery connector? is charging IC
And wide trace where silk marking CSP C 94V0-88S is VUSB 5V input
And also maybe on bottom side L1 and L2 are on USB data+ and data- lines

Take care
You can't find continuity of 5V input on battery connector
5V -> charger IC input- charger IC output (4.2V) -> battery connector.
In that case
5V -> U1 pin 1 (input) -> U1 pin 8 (output) -> battery connector

[M.A.L.S]

On that header on bottom of PCB you have VUSB and GND,you may apply 5V from external power source and see if charging.
If not,VUSB maybe not really routed to that header or for charging you need short or something on USB dataa+ and - lines.

Looking again at photos looks like U1 near battery connector? is charging IC
And wide trace where silk marking CSP C 94V0-88S is VUSB 5V input
And also maybe on bottom side L1 and L2 are on USB data+ and data- lines

Take care
You can't find continuity of 5V input on battery connector
5V -> charger IC input- charger IC output (4.2V) -> battery connector.
In that case
5V -> U1 pin 1 (input) -> U1 pin 8 (output) -> battery connector

Thanks for the info. Yes it does look like u1 is the charge controller but unfortunately the only markings on it are “NXE” so I wasn’t able to confirm that. Google didn’t have much. That said I did a continuity test from pin one to C4 and they are connected so yes it looks like that is the 6v input and pin 6 is the output. I unfortunately do not have a bench psu so I cannot hook up to test that. I could do a bodge and trim a USB cable and solder the hot wire to pin 1 and black to the test point gnd on the other side of the board and see what happens. Don’t really want to though just in case it damages something.

I did some further probing and found for U1 pin 6 goes to the top pin of the battery connector. Pin 7 goes to pin 2. pin 8 goes to pin one and two of the battery connector. Pin 9 goes to pin one on the battery connector and the last pin does not connect to the battery connector.

Would it be safe to hot mod a USB cable just to see if the board charges? As I said I don’t have a bench psu so that would be my only option to apply 5v to the board.

Thanks.

[M.A.L.S]

That said I don’t think the board will charge because I’ve removed the switch as I’m waiting for a replacement for the one I broke. Can’t remember if the board charges when it’s turned off, but since the switch is removed that would make it a open circuit wouldn’t it?

[gabiz_ro]

I don't know where switch is locates.
But tracking traces on PCB seems like charging is straight from USB connector.

NXE seems to be Bq24040
Are you counting right pins?
(from photo I was wrong,assuming 2x4 pins,but looking again is 2x5)
So pin 1 input VUSB, pin 10 output to C5 and Batt+ (three pin connector)
Is that three pin connector battery connector?

[M.A.L.S]

I don't know where switch is locates.
But tracking traces on PCB seems like charging is straight from USB connector.

NXE seems to be Bq24040
Are you counting right pins?
(from photo I was wrong,assuming 2x4 pins,but looking again is 2x5)
So pin 1 input VUSB, pin 10 output to C5 and Batt+ (three pin connector)
Is that three pin connector battery connector?

The switch is in the top right hand corner of the board where it says “off” for pin 1, “sw” for pin 2 and “on” for pin 3. Visible in the first picture top right corner.

Yes when I say pin 6 that’s the first pin on the right, directly opposite to pin one judging by the pin 1 marker.
Yes it’s 2x5 pins for what we suspect is the charge chip. Yes far right 3 pin connector is the battery connector. The battery has red, yellow and black. I’m assuming the yellow is for temp sensing.

[gabiz_ro]

I think it should charge no matter of on-off switch.
That is pin 10 not 6
Counting is like
1-10
2- 9
3- 8
4- 7
5- 6

You could use USB cable to board and see if charge.
Don't go blind and assume USB wires respect designed color,red 5V black gnd green and white data.Better check first.I've find many that don't match that .
5V to C4 side which goes to pin1 and gnd to some gnd on board or the other side of C4

[M.A.L.S]

I think it should charge no matter of on-off switch.
That is pin 10 not 6
Counting is like
1-10
2- 9
3- 8
4- 7
5- 6

You could use USB cable to board and see if charge.
Don't go blind and assume USB wires respect designed color,red 5V black gnd green and white data.Better check first.I've find many that don't match that .
5V to C4 side which goes to pin1 and gnd to some gnd on board or the other side of C4

Ah didn’t know that I thought they always go back to the top to continue. Thx for that.

I’ll try hook it up and see if it charges. I’ll post back findings.

[M.A.L.S]

I think it should charge no matter of on-off switch.
That is pin 10 not 6
Counting is like
1-10
2- 9
3- 8
4- 7
5- 6

You could use USB cable to board and see if charge.
Don't go blind and assume USB wires respect designed color,red 5V black gnd green and white data.Better check first.I've find many that don't match that .
5V to C4 side which goes to pin1 and gnd to some gnd on board or the other side of C4

Confirmed red is 5v and black is indeed ground. Confirmed pin 2 for c4 is indeed ground. Hooked up the respective wires and the light turns on than stays off. When it’s charging it normally pulses so it looks like yes you do need to short the sense lines.

[gabiz_ro]

I'm not 100% sure but like I said L1 and L2 could be on data+ and data- USB
Now depends on how is designed?
Is USB only for charging? Or have some USB connectivity? Need to be switched on to have USB connectivity?
When off and connected to PC USB was detected by PC?
First check if any voltage present on L1 and L2.

Then you may try to test data+ to L1 and data- to L2 if not ok swap them.
Or short L1 to L2
And see if charging

[M.A.L.S]

I'm not 100% sure but like I said L1 and L2 could be on data+ and data- USB
Now depends on how is designed?
Is USB only for charging? Or have some USB connectivity? Need to be switched on to have USB connectivity?
When off and connected to PC USB was detected by PC?
First check if any voltage present on L1 and L2.

Then you may try to test data+ to L1 and data- to L2 if not ok swap them.
Or short L1 to L2
And see if charging

Scratch that it is charging now. The light turned off hence why I thought it wasn’t but I’ve left it on charge for a half hour now and the battery’s gone up from 3.8 to 4.0 volts so it is charging. I guess it needs USB sense for the light to give the charge status.

No USB does data as well, you can use it as a wired keyboard if you want but if I remember right you had to turn it on to do so. Not 100% on that though as I haven’t used it like that much at all.

Now all I need to do is find a switch for replacement. This one has two pins much closer together than the third further away. Couldn’t find one like that but did find a 3 pin one from Jaycar so I’m going to try add some enamel wire and wire it that way. Probably won’t be here till Tuesday or so, thank you snail post!