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Scott Dorsey Scott Dorsey is offline
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Default Hail Mary for my sustain pedal.

In article , Tobiah wrote:
I went to play a piano piece tonight, and the sustain pedal wasn't
working. Yamaha So8 - USB MIDI - Windows 10 - any program I try.

So I knew it was the pedal, because I've had it for around 20 years
and I've repaired it many times. After some work at the bench, I
decided that the pedal was fine. I rebooted everything and checked
again. None of my software would react to the pedal. I loaded a
piano sound into a popular software synth product, and I could see
its MIDI reception indicator blinking with each press and release
of the pedal, so I knew the signal was getting there, but no product
I have seems to react to the sustain pedal.


So, you know it's sending something. But you also know that whatever
it's sending isn't the right thing. First thing is to look at the MIDI
port with a raw midi viewer and see what bits are coming down the line
when that light flashes. If you're lucky, nothing will be seen by the
interface at all.

If that's the case, put a scope on the thing and look at the waveform
when you press the pedal. The bits should be the right length, and they
should be nice and squared up. You might see some overshoot since it's
not going into a terminated load, but you shouldn't see weird irregular
junk or hum.

The most common failure here is for power supply capacitors to go bad
causing 120 Hz modulation of the signal, and that will be very obvious
on a scope. But other stuff fails too... those cheap ceramic resonators
that are often used in place of a real crystal can drift, and then you
get bits that are too wide or too narrow.

It can help to put a scope on a working MIDI device so you can judge what
the waveform should look like and how wide the bits are. Remember the
start bits are much wider than the actual data bits, and you should be
able to trigger the scope on the start bits and see the whole word on the
screen at once.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."