Our 61-key Yamaha PSR-275 is the keyboard in our Hammond organ rig, and it reaches the laptop through a Roland UM-ONE. The PSR-275 came out in 2003, before home keyboards had USB, so its only way to talk to a computer is MIDI: the musical-instrument standard from 1983, carried on cables with round 5-pin plugs. The UM-ONE mk2 is a USB cable that ends in two of those plugs. Once it’s connected, the keys can play software instruments, record into music programs and drive our online piano, and the computer can play the Yamaha’s own sounds.
What you need
- The Yamaha PSR-275 (or its sister model, the PSR-273, which shares the same manual and the same MIDI sockets).
- A Roland UM-ONE mk2. The MIDI and USB cables are built in, so there’s nothing else to buy. It takes its power from the USB port (70 mA, according to Roland). Roland Australia now lists it as discontinued, so expect old stock or second-hand.
- A computer with a USB-A port, or a USB-C to USB-A adapter. Windows, Mac and Linux all work. So does an iPad, with Apple’s camera adapter.
- Music software, which can be free: our online piano to test with, GarageBand on a Mac, MuseScore Studio for writing notation, or any recording program (a DAW).
One thing to know before you start: MIDI doesn’t carry sound. It carries instructions: this key, this hard, now; that key let go. The computer makes its own sound from them, or sends them back to the Yamaha to play. If you want to record the Yamaha’s actual voices, that takes an audio cable, which we cover further down.
Step 1: Plug it in the right way round
This is where most first attempts go wrong, because it looks backwards. The UM-ONE’s two plugs are labelled from the interface’s point of view, not the keyboard’s. So:
- the plug marked IN goes into the keyboard’s MIDI OUT socket (Roland’s spec sheet says so: “connect to MIDI OUT”);
- the plug marked OUT goes into the keyboard’s MIDI IN socket.
Think of it as out goes to in, like a conversation: one side’s mouth talks into the other side’s ear. The two MIDI sockets are on the PSR-275’s back panel, labelled MIDI IN and MIDI OUT, next to the sustain pedal jack.
Roland’s manual says to plug the USB end in after the computer has finished starting up, because some computers won’t see it if it’s connected during start-up. Plug it straight into the computer rather than a cheap unpowered hub, at least for the first test.
Step 2: Set the COMP/TAB switch
The UM-ONE mk2 has a small slide switch on its body marked COMP and TAB. It chooses which driver the interface expects:
| Switch | What it means | Driver |
|---|---|---|
| COMP | Roland’s own driver mode. The manual pairs it with computers. | Install Roland’s UM-ONE mk2 driver first. Roland lists versions for Windows 10 and 11 and for macOS 11 Big Sur and later. |
| TAB | Class-compliant mode: it behaves like any standard USB-MIDI device. The manual pairs it with the iPad. | None to install. Roland’s support pages say it then uses the MIDI driver built into the computer or iPad. |
Our advice: try TAB first on any computer, because there’s nothing to install and nothing to go wrong with a driver. Class-compliant is also how our own UM-ONE runs on Linux: the standard Linux USB audio driver handles it, and aconnect -l lists it as “UM-ONE”. Switch to COMP and install Roland’s driver only if a program you rely on asks for it, or if TAB gives you trouble. If you do use COMP, install the driver before plugging the UM-ONE in, as Roland’s manual says. (Our own interface is the older UM-ONE, so we haven’t tested a mk2 ourselves.)
Set the switch with the USB unplugged. If you change it while it’s connected, unplug the USB and plug it back in so the computer sees the change.
Is yours the original UM-ONE?
Ours has a switch marked COMPUTER and MIDI instead of COMP and TAB, which suggests it’s the original UM-ONE from before the mk2. If yours has that switch, set it to COMPUTER; that’s how ours runs. The plugs work the same way as the mk2’s.
Step 3: Read the three lights
The UM-ONE mk2 has three small indicators, and they tell you how far the signal is getting:
| Light | Lights when… | If it doesn’t |
|---|---|---|
| USB | the computer has found the UM-ONE | Try another USB port and plug it in after start-up. In COMP mode, check the driver is installed. |
| MIDI IN | MIDI data is arriving from the keyboard | The IN plug is probably in the keyboard’s MIDI IN socket by mistake. Swap the plugs. |
| MIDI OUT | the computer is sending MIDI to the keyboard | Your program isn’t set to send to the UM-ONE yet. Normal if you’re only playing into the computer. |
A PSR-275 quirk: ours sends a constant stream of MIDI clock, a timing signal, whether or not you’re pressing keys, so the MIDI IN light can flicker even when nobody is playing. A flickering light proves the cable is the right way round, but not that notes are getting through. The next step proves that.
Step 4: Test it in your browser
The quickest test needs no software at all. Open our online piano in Chrome or Edge, press Connect a MIDI keyboard and allow access when the browser asks. It should say Connected: UM-ONE. Now play the Yamaha: the keys on screen light up as you play, and the page plays its own piano sound, with chord names, so you know every note is arriving. (Safari and iPhone and iPad browsers don’t support MIDI on web pages yet.)
Another quirk: ours plays an octave low. Our PSR-275 sends notes 24 to 84, an octave below the 36 to 96 you’d expect from a 61-key keyboard. On the online piano, the keys light up one octave to the left of the one you’re playing, and the lowest octave still sounds but falls off the end of the drawn keyboard. First check the Yamaha’s own Transpose setting reads 00 (press FUNCTION until the display shows Transpos). If it still plays low, set your music program to transpose its MIDI input up 12 semitones, or one octave. Most have a setting for it.
Step 5: The two PSR-275 settings that matter
The PSR-275 doesn’t let you choose the MIDI channel its keys send on, and there’s no menu of MIDI options to wade through. Two settings are worth knowing.
Local Control: stop the keyboard playing its own sounds
Normally a key does two things at once: it plays the Yamaha’s built-in voice, and it sends a MIDI note out of MIDI OUT. Local Control is the link between the keys and the built-in voices. Turn it off and the keys still send MIDI, but the Yamaha stays silent, so you only hear the computer. Yamaha’s manual puts it simply: with Local off, no sound comes from the keyboard.
It matters most when the computer sends your notes straight back to the Yamaha, which many recording programs do while you record (it’s often called MIDI thru or echo). With Local on, every note then sounds twice: once from the key and once from the computer.
There are two ways to switch it:
- The PC button. Press [PC], then [+] or [−] to switch PC mode on or off; the display shows which. PC mode is Yamaha’s one-button setup for using the keyboard with a computer, and what it changes is Local Control: PC mode on means Local off.
- The Function menu. Press [FUNCTION] repeatedly until the display shows Local, then use [+] and [−] to set it on or off.
Remember to turn Local back on when you unplug and want to play the Yamaha by itself again, or it will seem to have stopped working. If you’re playing a software instrument and don’t need the computer to send anything back, simply turning the Yamaha’s MASTER VOLUME down does the same job.
External Clock: leave it off
The Function menu also has ExtClock. When it’s on, the Yamaha’s styles and songs wait for timing from the computer instead of their own clock, and they won’t start at all until it arrives. It’s off by default. If the styles ever refuse to start while the keyboard is connected, check this first.
The other direction: let the computer play the Yamaha
The PSR-275 isn’t just a keyboard; it’s also a full General MIDI sound module (GM System Level 1). Its manual says that by default it works as a 16-channel multi-timbral tone generator: it can play 16 different instruments at once, one per MIDI channel, with up to 32 notes sounding together. General MIDI means a standard MIDI file (.mid) gets the right instruments: piano on piano, bass on bass, drums on the drum kit.
To use it, plug the UM-ONE’s OUT plug into the Yamaha’s MIDI IN socket, choose UM-ONE as the MIDI output in your music software, and play a MIDI file. The MIDI OUT light on the UM-ONE flickers, and the Yamaha plays the whole arrangement with its own voices. Two nice touches from the manual:
- notes arriving on MIDI channel 1 appear on the Yamaha’s display, so you can watch the melody;
- incoming MIDI plays on its own channels without changing the voices you’ve chosen on the panel (though a file can change the reverb, chorus or tuning, or reset the keyboard to its defaults).
A tip if you record onto a computer and want the Yamaha to play it back exactly as you heard it: Initial Setup Send (InitSend in the Function menu, then [+/YES]) sends a snapshot of the keyboard’s current settings to the computer. Record that at the very start of your song and the Yamaha is set up the same way every time it plays it back.
What the PSR-275 sends
Yamaha’s MIDI implementation chart for the PSR-275 (dated 29 January 2003, at the back of the manual) lists exactly what goes out of MIDI OUT. In plain English:
| Sends | What it means for you |
|---|---|
| Notes, with how hard you played them | Every key, on and off. The keys are touch-sensitive, so loud and soft playing come through, which matters for piano software. |
| The sustain pedal | Plug a Yamaha FC4 or FC5 footswitch into the SUSTAIN jack and it works in software too. (In our organ rig, it switches the Leslie speed.) |
| Voice changes | Choosing a voice on the panel sends a program change, which some programs use to switch sounds. |
| Clock, start and stop | The constant clock behind the flickering light, plus start and stop messages for its styles. |
| Not pitch bend or modulation | The PSR-275 has no pitch-bend or modulation wheel, so neither is sent from the keys. |
Recording the Yamaha’s own sound
Because MIDI is only instructions, the UM-ONE can’t carry the Yamaha’s actual audio to the computer. You have two choices:
- Record MIDI, play it back on the Yamaha. Record the performance over the UM-ONE, then send it back out to the Yamaha’s MIDI IN to hear it. You can fix wrong notes and change the tempo afterwards, which you can’t do with a sound recording.
- Record the audio. Run a cable from the Yamaha’s PHONES/OUTPUT jack on the back panel to the computer’s line input, or better, to a USB audio interface. Plugging in here switches off the keyboard’s own speaker. Keep the Yamaha’s volume moderate so the recording doesn’t distort. A laptop’s microphone socket is the wrong level for it: use a line input.
Many people do both: MIDI for the performance, audio for the sound. (Going the other way, getting the computer’s sound to good speakers, is its own topic: see computer to speakers.)
When nothing plays
Work down this list in order. The first two items cause most problems.
| What you see | Likely cause | Fix |
|---|---|---|
| Nothing arrives, MIDI IN light dark | Plugs swapped | The plug marked IN goes into the keyboard’s MIDI OUT. |
| Nothing arrives, USB light dark | Computer hasn’t found it | Unplug and replug after start-up, try another port, skip the hub. In COMP mode, install Roland’s driver. |
| The UM-ONE isn’t in the program’s list | Wrong switch position, or it was plugged in after the program opened | Try TAB. Close the program, replug the USB, then open the program again. |
| It worked yesterday, not today | The computer went to sleep, or it’s in a different USB port | Close the program, unplug and replug. On Windows with Roland’s driver, use the port you first installed it on. |
| “Device in use” on Windows | Another program has the UM-ONE open | On Windows, a MIDI port can often be used by only one program at a time. Close the other one, including browser tabs using MIDI. |
| Every note sounds twice | Local on, and the computer echoes notes back | Turn Local off (the [PC] button), or turn off the program’s MIDI echo. |
| Everything is an octave low | The PSR-275’s note range (ours sends 24 to 84) | Check Transpose is 00, then transpose the program’s input up 12. |
| The Yamaha is silent on its own | Local is still off | Turn PC mode off ([PC], then [+] or [−]), or set Local on in the Function menu. |
| Styles won’t start | External Clock is on | Set ExtClock off in the Function menu. |
Got an old keyboard that won’t talk to your computer?
Lots of good instruments from the 1980s to the 2000s have only 5-pin MIDI, and almost all of them connect the same way as this one. If yours is fighting you, or you’d like a hand setting up recording software, we’re happy to help.
Common questions
Does the Yamaha PSR-275 have USB?
Which UM-ONE plug goes into which socket?
Do I need to install a driver for the UM-ONE mk2?
Will the UM-ONE send the keyboard’s sound to the computer?
Why does the UM-ONE’s MIDI IN light flicker when I’m not playing?
Can the computer play the PSR-275’s sounds?
Sources: Yamaha PSR-275/PSR-273 Owner’s Manual (MIDI Functions, Function list and MIDI Implementation Chart); Roland UM-ONE mk2 specifications and the UM-ONE mk2 Owner’s Manual (panel descriptions, connections, troubleshooting), from Roland support, and Roland’s help article on connecting the UM-ONE mk2 to a computer; and our own PSR-275 and UM-ONE, in daily use in our organ rig. Checked 3 November 2026.