Logitech K750 ‘repair’

tl;dr: Thought keyboard was broken, only needed battery replacement.

k750Since the Logitech K750 was first released, I was a fan. But the $100 price tag put me off. It’s most noticeable feature is the fact that it has a bar of solar panels along the top of the board which are used to charge the built in battery. This should mean you never have to replace the battery. A dream come true to me, who in general is disposable battery averse. Besides that it’s a standard wireless keyboard that uses Logitech’s unifying receiver, I additionally like the style and design of the keyboard.

So joyous was I to find it on a half-price special at some stage, promptly ordering it and enjoying it’s use. Two years later, on returning from a short trip, the keyboard no longer worked. Not registering keypresses, nor activating any of it’s notification lights. The battery is not supposed to be replaced, but is relatively easily accessible, so I popped it out and measured the voltage.

ml2032The battery used is a rechargeable coin-cell battery, similar to what is used on motherboards, an ML2032 3.0V battery. My battery measured 2.9V, so I assumed it was still fine, and something else had gone wrong. The keyboard had a 3-year warranty I was still within, so after the retailer rejected me, I contacted Logitech who were kind enough to send me a replacement that continues to work perfectly.

This was over a year ago; in-between a lot has happened, but Logitech didn’t ask me to return the old keyboard, and I couldn’t bring myself to throw it out. I figured I’d salvage the solar panels or something. I found it the other day and decided to take another look. Although the battery comes out relatively easily, the keyboard’s faceplate is glued into place. So to disassemble it you have to pry that off, making reassembly difficult.

After that there are a number of screws to remove, and then the base separates, giving you access to the circuit-board. On the front are a few test-points. With my old battery plugged in, V_BAT showed 2.86 V and V_MAIN showed a steady 2.0 V. I tested some other components but couldn’t find anything notably wrong with the board. Solar panels provided a charge.

So I popped my battery out of my new keyboard, and lo and behold it worked. I measured the voltage and it reflects marginally over 3.03 V. Apparently a 0.15 V drop on this battery is enough to stop the keyboard working. I measured the V_MAIN on the test points, and it showed an match 2.0V, like with the ‘bad’ battery. This also meant my disassembly was completely unnecessary. So with it in pieces, I ordered a replacement battery.

Now I have two working K750 keyboards, although one is slightly disfigured.

April 2021 Update:
My original keyboard is still working after replacing the battery.
My second only somewhat works. If I try turn it off, it doesn’t turn off immediately, but only after a few minutes. Once it’s off, it can’t be turned back on. However, I’ve found that if ‘jumpstart’ it by shorting the V_BATT and V_MAIN terminals together for a few seconds, then it works again until it is turned off.

Logitech K750 – Solar Keyboard

For the past few years, ever since I got a laptop, I’ve used a laptop stand with a built in keyboard, and although a bit limiting as far as manoeuvrability is concerned, it’s worked quite nicely. It allows my screen to be lifted up, and puts it a bit further away from me, while also giving me a full size keyboard to work on.

It’s not an amazing keyboard but it’s done me quite well, until earlier this year when I upended a cup of coffee onto it. To it’s credit, after I stripped it, drained it, and cleaned off as much of the sticky stuff as I could, it continued to work. But the stickiness is still there, impeding my typing. And so I was looking around for keyboards, but couldn’t find one I liked.


I knew which keyboard I wanted, it was this one (Logitech K750). The solar powered one :) but it was R1,000. And I wasn’t going to pay that much for a keyboard. Ideally I was looking for a wireless ‘island’ key layout, much like my laptop’s keyboard. But I couldn’t find one in I wanted to buy..

And so I resigned myself to sticking to my sticky keyboard. Until Takealot had a daily deal and I picked the same keyboard up for halfprice, much to my delight. In typical Takealot fashion, they completely over-packed the box, but the keyboard itself comes in a slim box, with only the essentials. The keyboard itself is very thin, but with a surprising weight to it. It has some flex to it, and two spindly legs to raise it, but it all seems sturdy enough.


The keyboard has a nice gloss finish (it even comes with a cloth), with the two ‘large’ solar panels taking up space along the top of the keyboard. The keyboard makes use of Logitech’s unifying remote, and even comes with a small extension for plugging in the back of a desktop PC.

The letters on the keys are in the middle or slightly below the centre of the button, which makes it look odd, but obviously has minimal impact. One thing I am missing straight off the bat, is the lack of wrist rest. My laptop obviously has one, and my laptop stand also had a rather sizeable one. But I’m sure the lack of this will be forgotten in time.

A keyboard, below a keyboard, below a keyboard

A keyboard, below a keyboard, below a keyboard

The keyboard has an on/off switch, assumedly to spare a bit of battery and a ‘light testing’ button, which when pressed illuminates a green or red LED depending on how much light the panels are receiving at the time. The keyboard is also designed to never have its battery replaced. Only time will tell, but that’s obviously why we have the solar panels.

Overall a very nice keyboard that I’m happy with. The layout is ever so slightly larger than my old keyboard, so my fingers feel slightly stretched, but I don’t know if that’s actually true or if it’s just the lack of wrist rest that makes me think that. Now I just need to build a new laptop stand for myself.


note: the actual title of this article is “/me ‘greater than symbol’/3 Logitech” but it appears WP sees this as some kind of html code, so…

I’ve always been a fan of Logitech products. They make good, hardy and elegant/pretty looking hardware. I’ve had my current wireless mouse/keyboard set for the past 5 years without any problems. And so it was with great excitement that I purchased a second hand set of Logitech 2.1 speakers about a year ago. They were a great set of speakers, and a massive upgrade from old cheap standard “comes with the PC” speakers I had been experiencing the last 10 years.

Suffice to say, I never knew what I was missing in terms of sound until I had listened to music through these speakers, and these are fairly entry level speakers from Logitech. In any case, it made beautiful music and pumped a previously unheard amount of bass out. That was until about three days ago when I got back from class turned on my music and nothing happened. I check all the plugs and connections in my PC and I notice that the power light is off, even though it should be on.

So I follow the wires back to the sub. A beautifully sealed wooden box. I unscrew all the screws I can find which results in a small opening on the back of the case in which I can look in. I do a quick multimeter test and it appears as though the transformer isn’t putting out any current. That’s ok, but I can’t get to the transformer, and can’t get any of the electronics out to test components. I look in and can see that all the planks have been glued together, to give a lovely, no nails, no fuss (for assembly) product.

My only option really is to try split the case down one of the joins. I manage this down the one side, damaging the fascia quite noticeably, But find to do one of the other sides is going to be virtually impossible. 10min worth of trying has me splitting the wood in places it wasn’t supposed to. So I went and bought myself a hacksaw :D

A lot of sawing and dust later and I find myself with a plank of wood with a fairly large transformer attached to it. I still can’t take most of the electronics out as the wires attached to the speaker are too short and are soldered on every where. Pull out the soldering iron, which decides it no longer wants to work, take it apart and decided I need a soldering iron to fix it. To fix my soldering iron in any case.

So that’s where I am at the moment. Sitting with a broken speaker set, broken soldering iron, and my Headphones need some soldering work themselves. But what am I to do…

I miss music in my room.