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Repair information for the Logitech K750 wireless solar keyboard. First available on Amazon in 2011. Model numbers: 920-002912 (Windows), 920-003472 (Mac).

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Changed battery but still no signs of life?

I have bought and replaced the battery with an Maxell ML2032, but the keyboard doesn't show any signs of life. There is no green or red LED in the top right corner and the keyboard is not found by the unifying software. Each of the solar panels gives about 1.5v output when tested with voltmeter and the battery itself gives just over 2.8v (the old battery has less charge and gives about 1.2v).

Is there anything else that I might be able to do to fix the keyboard, I don't want to have to replace it?

Thanks in advance for any suggestions.

Scott.

Answer this question I have this problem too

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same here. you are not alone

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Same here, My third K750 keyboard in 6 years this happens, 2 years of use then dead. So there is a 24 month kill timer inside for sure = design to fail. No more Logitech for me

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Turn the battery over. With the keyboard right side up you should see the smaller negative side up.

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Just for clarification, the correct position of the battery is shown in the step 5 of how to change the battery: Logitech K750 Keyboard Battery Replacement

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You could have a look at the power (On Off) switch. On my K750, this switch is starting to fail causing symptoms like you describe.

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I have this problem (Logitech has put obsolescence on the switch too to kill the keyboard). Curiously, the switch is always "on" and drain the battery even if we do not use it.

Have you solve the problem ? How ?

Thanks.

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Turn the battery over before anything else

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Hi Scott, my guess would be that the logic board may need to be replaced OR a cable could have come dis-connected from the board or the battery itself. I suggest trying to re-install the new battery.

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seems reinstall makes no difference. for me zero power even with new battery. how to fix worn power switch?

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I have two of theses, both went down within the last month, I changed ther ML2032 battery in both, still no life, Logitech are holding something back from us regarding the answer!

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Turn the battery over before anything else

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Turning battery over was the game changer, installed replacement wrong and then just put old one back in (battery goes in opposite of what you'd think). Also used a hack of turning off keyboard, holding CAPS LOCK down and pressing buttons for 5 seconds and then turning keyboard back while under direct light.... .those 2 things revived my keyboard.

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Larry Jackson and Rob Lazott, you both just made my K750 keyboard go from dead to back to life! Thanks so much for the tips on turning over the battery AND the CAPS LOCK trick. I'm back to seeing green! :D

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If the battery and solar panels are providing correct voltage, the issue is likely not power-related. First, try resetting the keyboard: remove the battery, cover the solar panels, leave it disconnected for 30–60 minutes, then reinstall the battery under bright light. Also clean the battery contacts and PCB with isopropyl alcohol to remove oxidation. Check for loose ribbon cables or cracked solder joints, especially near the battery holder. If there’s no LED response and it’s not detected by Unifying, the power management IC or RF module may have failed, which is unfortunately not user-repairable. At that point, replacement may be the only option.

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Thanks,

EDIT: Sadly this did not fixed it, so i have to open it. - I will remove the battery, cover the solar panels and leave it disconnected for 30–60 minutes. If that does not work i will open it. I found a guide here. Sadly i have already discarded my 2 older K750s.

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@peterperss42351 K750 keyboard has a weird type of design with planned obsolescence. Opening it would destroy and cannot be repaired. There is no ribbon cable between battery and PCB. PCB has two sided connections for solar panels. The 30 pin FPC connector has a large plastic type traces which itself is a folded leaflet book type design with thin carbon traces. 4 pins go to the on-off switch and connects to 3pin switch. even green and red leds are sandwiched so not an easy repair.

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It's a destructive process and not worth the time for a repair. Additionally, the tiny rechargeable lithium battery is not the culprit. It is designed to auto sleep even when you forget to turn off the power switch. The plastic leaf like carbon printed circuit board is the one that fails.

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scott adam will be eternally grateful.
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