How would you test a midi controller with just a multimeter?

[Doc]

When Pawn-shopping looking for a barebones midi controller (looking for a 76
or 88 weighted-key unit to do some real keyboard practicing) what would be
the procedure to verify output using a multitester on the midi ports? I
don't have a laptop DAW and obviously lugging around my PC is impractical.

What problems could there be that verifying output voltage won't tell you?
Can you test for things like pitch-bend function this way?

Any additional hints/tips on things I should look for or otherwise be aware
a/or wary of (including brands/models to avoid) are also welcome.

Thanks for all shared wisdom and happy whatever it is, if anything, you
celebrate.

[Richard Crowley]

"Doc" wrote ...

Post by Doc
When Pawn-shopping looking for a barebones midi controller (looking for a 76
or 88 weighted-key unit to do some real keyboard practicing) what would be
the procedure to verify output using a multitester on the midi ports? I
don't have a laptop DAW and obviously lugging around my PC is impractical.
What problems could there be that verifying output voltage won't tell you?
Can you test for things like pitch-bend function this way?
Any additional hints/tips on things I should look for or otherwise be aware
a/or wary of (including brands/models to avoid) are also welcome.
Thanks for all shared wisdom and happy whatever it is, if anything, you
celebrate.

If you just wanted to check to see if the "mystery equipment" was
emitting MIDI when you press (and release) keys, and when you
move the pitch-bend wheel, etc. you could try rigging a test cable
that would have the MIDI DIN connector on one end and something
to plug in a headphone (or earpiece). You could "calibrate" your
ear to hear what "good MIDI" sounds like, and then whip it out
to do a "go/no-go" test on the MIDI output. Or visually with....
http://www.epanorama.net/circuits/miditest.html

[Mike Rivers]

Post by Doc
When Pawn-shopping looking for a barebones midi controller (looking for a 76
or 88 weighted-key unit to do some real keyboard practicing) what would be
the procedure to verify output using a multitester on the midi ports?

I like that homebrew MIDI output tester. MIDI is a current loop, not a
straightforward voltage source, and if you aren't as old as I am,
chances are your multimeter has a digital readout rather than a meter
pointer - hard to see any activity on that.

But most places that sell used keyboards usually have more than one.
Why not just connect its MIDI output up to the MIDI input of another
synth on the shelf and see if it works? Or if you have a compact sound
module, take that along with you instead of your multimeter.

I'd check that all the keys work.

[Sylvain Robitaille]

Post by Doc
When Pawn-shopping looking for a barebones midi controller (looking
for a 76 or 88 weighted-key unit to do some real keyboard practicing)
what would be the procedure to verify output using a multitester
on the midi ports?

What I use is a home-made MIDI tester: simply an LED wired (in correct
orientation; I don't have the unit with me, or I would describe exactly
which pins, and the orientation, but MIDI connections are well
documented on the 'net and elsewhere) across the two signal pins of a
DIN-5 socket. I take that along with a known good MIDI cable, and I can
get at least a quick "sanity" check. Ie, MIDI is being output or it
isn't.

I hope that helps ...

[Gareth Magennis]

Post by Doc
When Pawn-shopping looking for a barebones midi controller (looking for a 76
or 88 weighted-key unit to do some real keyboard practicing) what would be
the procedure to verify output using a multitester on the midi ports? I
don't have a laptop DAW and obviously lugging around my PC is impractical.
What problems could there be that verifying output voltage won't tell you?
Can you test for things like pitch-bend function this way?
Any additional hints/tips on things I should look for or otherwise be aware
a/or wary of (including brands/models to avoid) are also welcome.
Thanks for all shared wisdom and happy whatever it is, if anything, you
celebrate.

Just bring along a LED. You can shove the leads into the two MIDI Out
connections either side of the centre pin. It will only work one way round
so try both ways. Transmitting data will make the LED light. Things like
pitchbend and aftertouch chuck out a lot of data and the LED will light
quite brightly. Playing individual notes gives a rather harder to see
effect, especially in bright ambient light, but be aware that these
functions may not be turned on, so banging a handfull of notes is the best
idea. If you have a MIDI keyboard at home, give it a try, you won't break
anything.



Gareth.

[Joe Kesselman]

Post by Doc
When Pawn-shopping looking for a barebones midi controller (looking for a 76
or 88 weighted-key unit to do some real keyboard practicing) what would be
the procedure to verify output using a multitester on the midi ports? I
don't have a laptop DAW and obviously lugging around my PC is impractical.

Borrow an external MIDI module? (From someone who won't kill you if they
unit you're testing is broken enough to fry anything attached to it...)