Adding Battery Power to the Tenori-on O

Hello! How’s it going? Long time no see. I used to log in here literally every day, but our paths diverged and… anyway, I hope you don’t mind me popping back to gather the community’s thoughts on something.

Does anyone still use the Tenori-on? Or am I the only one? Sure, it’s hella limited, but I enjoy messing around with this weirdo of a sample player.

I have the later, cheaper TNR-O, the plastic white one with orange led, as opposed to the metal one. I’ve never really wanted a metal one over the plastic one, apart from one thing - the battery power.

I’ve considered buying a 12v battery pack and velcro-ing it to the back but that isn’t an elegant solution, so today I thought to myself - I wonder how much of the original Tenori-on guts were left in the plastic revision and it turns out, A LOT.

Here are some photos of the inside of the original: Tenori-On Teardown « bunnie's blog

And here is a photo of the inside of my TNR-O:

The eagle-eyed amongst you will see that they’ve used exactly the same circuit board, but haven’t populated the back LED display (look at all those blank solder pads), or the battery connector to the left of the power switch.

I’d like to add a USB charging board, and a rechargable battery, and solder it to these connections, and from the photo on the site I shared I think I can work out what goes where. I just have a few questions:

-Does anyone else own a TNR-O and want to join me in this quest?
-Would anyone be willing to offer advice and support on batteries and charging boards? I know a little, but only from doing mods to other devices that others have already documented.
-The only issue I can see is if there is more to the TNR-O switching between battery and mains power than just adding a battery. Does anyone know if there any way to check this before I start on this mission?

Big love!



I’ve been eying the Tenori-On again recently. Sold mine unfortunately some years ago, but the simplicity and also the new alternative firmware do appeal to me. I’ll be keeping up with this thread as it seems like a very realistic task to achieve. I’m sure modern batteries will run great in the device. Crossing my fingers that you get it to work :slight_smile:


Thank you so much for that link; had no idea there were custom firmwares!

Tenori is maybe my most favorite instrument but I own a metal one that’s a little finicky… The left quick select buttons are not working and after attempting to unscrew the shell in order to see what was wrong, I realized the torque on several screws was far greater than what I could handle with my harbor freight tools and so I never did end up getting inside to see what the matter is. It’s on a list of tasks though, and even not being 100% functional, the lil guy is so fun to use (especially with folks who don’t think of themselves as musicians).

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Stoked to hear about the alternative firmware, too. Very cool.

Tenori is maybe my most favorite instrument but I own a metal one that’s a little finicky.

Mine’s the metal (TNR-W) version, too, and is finicky in a different way. The jog wheel has gotten really jumpy. It still works, but rather than smoothly scrolling through values or menu items, it jumps all over the place at random. Trying to select a specific setting is an exercise in frustration. Pretty annoying, but I’ve gotten used to it. I’m too scared to try to open mine up or spray some contact cleaner in there, so I just deal as best I can. It’s still one of my most immediate and playful music-making machines.

(Apologies to @Simeon for the brief hijack. Best of luck with the battery upgrade.)

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Hijack away! I’m glad to hear there’s a lot of love, and yes, there does seem to be a lot more of the metal ones out there than the plastic ones. I wonder if the TNR-O was just made to use up the parts like Fender did with the Swinger (Fender Swinger - Wikipedia)


I have both a silver one & an orange - I love them!! My orange one is in a case with pedals so I just power it as per the pedals… I prefer getting away from the super kawaii sounds & more into glitchy FM bit crushed territory using BitRman, Sonic Alienator & Microcosm via a Patchulator 8000.

I dont find the Tenori On limited, there are so many ways to play it but as with all synths processing & effects make a huge difference… I really like playing it (eg when overdubbing or jamming with other elements) with the tempo on maximum and a single busy/rapid sequence, and instead of tweaking notes, you use the instrument select mode as the main gesture - it almost becomes granular, depending what sounds you sweep through…


The difference between the TNR-O and TNR-W is very small; the schematics are identical except the TNR-O simply doesn’t have certain things fitted. You can see this in the service manuals by comparing schematics.
For example, this is the PSU end:

There’s some stuff as well around the CPU port AVCC (and signal AN2), but these feed the ADC for the TNR to display how full the battery is, so I don’t think you strictly need them. You’ve already spotted that the only other thing missing is the connector to the batteries.

I’d be very careful about overvoltage though.

In summary - I think that you can just wire a battery pack in, without having to do anything else, although you won’t get any battery symbol or feedback on what the battery level is. (All liability excluded, obviously. I’m not willing to try this on mine…)


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Amazing! Thanks, Pika! And for all your work with the community.

Having said “careful with overvoltage”, it looks like the firmware makes the distinction between battery and external power only by the measured supply voltage, so you are probably OK to go a bit higher than 9V. The Schottky diode in the external supply line drops about 0.5V, so you are probably OK up to 11.5V of battery…

For anyone following my progress, it’s not looking great for this fitting inside the case in an elegant way while also having a long enough battery life to make this worthwhile.

I’m currently looking at li-ion batteries, the charging board and a buck-boost converter (this kind of thing: SparkFun Buck-Boost Converter - COM-15208 - SparkFun Electronics)

Adafruits do an all-in-one power boost to 5v, but I can’t find one that does 9v, and heat has always been an issue people have mentioned. Seeing as I’m trying to cram this all into the plastic case that might not be ideal.

My last issue here is also battery life - the only way I could get the amp hours inside the case would be wiring more than one battery together, which brings it’s own headaches.

It may be than an external battery could end up being a more elegant solution if done nicely, something like a volto.


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This thread brought me such happiness as I thought my TO was permanently dead and thought nobody was working on it. I have a silver that stopped powering on two years ago and Yamaha won’t repair it. Based on your experience, do you have any recommendations for how I’d start identifying the problem? I’ve tried different batteries and adapters. Something is clearly broken in the device.

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I have been powering my tenori on for four years now with a 8 x aa battery housing with a simple kn off switch and cable connector velcroed under it… I get literally a whole week holiday on it noodling for ages.

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On my TNR-O, I was able to sort out the jumpy wheel issue by (opening the Tenori-on, then) removing the wheel, blowing it it, and tightening the screws on either side, which were very clearly loose on mine, likely far beyond what might have been intentional during assembly. I can’t say which of these things helped, but it was great to get inside this lovely creature and provide a good cleaning for the case.


I was just dealing with this issue yet again the other day, so thanks for the suggestions. I guess I’m going to need to summon the courage to open mine up. Given how much I love the device and how rare and expensive they are now, I struggle with leaving it alone vs. risking some all-thumbs screw-up while I’m in there trying to make things better.

Is the jog wheel accessible with just the rear plate off or do you also need to lift out circuit boards (or other guts) to get to it? I realize it might be different on the TNR-W vs. the TNR-O because of the rear LED panel.

I believe I was able to access the wheel without needing to remove any of the other boards, but I’m not certain of that; I ended up removing all the boards and lifting the grid out so I could do a thorough cleaning. I wish I’d noticed that one of the grid buttons was dead, though! Maybe when I try to do a battery mod, I’ll try to tackle that.

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Informative thread!

I was eyeing a tenori-on but was on the fence. Anyone who has one, what are the benefits of the custom firmware?


The main thing I like about the custom firmware is the way it can add different velocity values. The flat velocity on the original firmware makes it hard to get a good groove.

The creator of the firmware is active on the modwiggler tenori sub forum…