MIDI Trouble Shooting
Cited from http://homerecordinghub.com/midi-help.html
Quite often after you think you have everything setup properly, something doesn't work. When I try to troubleshoot a setup, I like to attack it in a flow from the beginning of the MIDI chain to the end. Here is a step by step guide that I like to follow and will offer you a place to start.
I can't tell you how frustrating it is to spend a half hour or more trying to figure out why something won't work and then to realize that the power switch is off. No matter how organized you think you are, or how good you memory may be, check the power on everything starting with the MIDI instrument, the MIDI interface (some don't have a power switch), and to the computer.
The more involved your studio setup gets, the more cables there will be. It still amazes me the mess of cables I have behind my computer when everything is setup. Make sure the ends of each cable are connected snuggly into the appropriate device. Check the end of every cable. Otherwise, the one you may neglect to check could be the one that is loose.
MIDI help! Check your cable "INs" and "OUTs"
Also don't forget to crisscross your MIDI cables so the "MIDI IN" goes to the "OUT" and the "OUT" goes to the "MIDI IN." If you have a mess of cables like I have, this can be a bit of a challenge. If it is only one device that is not working correctly, then what I usually do is reverse the MIDI in and out cables on the back of my keyboard that isn't responding. Sometimes, that is all it takes.
This problem happens a lot to me because I play keyboards in a band. When I go to practice or a gig, I have to unhook everything. When I go to set it all back up, instead of chasing wires one at a time through a mess of cables, I just swap the ends that don't seem to work. So far, when that is the cause of the problem, it has worked every time. A suggestion might be to try labeling your cables with a piece of tape. This may save you time when un-connecting and re-connecting all of the time. Hey, I'll have to try that!
Start with your MIDI instrument. Is it a complex machine that took months to learn and you still need the manual? Make sure you have it setup properly for MIDI communication. I use Alesis, Korg, Roland, Yamaha, and Casio instruments. Most of them (not the Casio) have a "Global" setting that needs to be selected. And I have to set them up differently when I'm playing them live versus using them for MIDI.
My suggestion, know your instrument by taking the proper time to learn it. Not only will you find it easier to use it, but you'll probably learn some cool things that it can do in the meantime.
Remember that your computer also needs to be configured. If you are using a PC, check your multimedia control panel and make sure that it is setup properly. Then check to make sure that the MIDI software you are using is setup correctly. If someone other than you likes to use your computer, you never know what could have been changed. It may even require you to have to crack the manual to find your MIDI configuration window. Knowing your software well is also as helpful as knowing your instruments well. It's a lot quicker to check your settings when you know right where to look for them.
Speakers / Studio Monitors
Although I have not talked much about this, you also have to make sure that all of your external audio gear is turned on. Check your amp, mixer, EQ, and all the wires involved. Sometimes it is as simple as a loose speaker wire.
If you have had a keyboard or another complex MIDI instrument for a long time and made lots of changes to it, it may start to act funny. I had a keyboard once that after a while, the touch sensitivity would reverse. When I would press the keys down hard, the sound was soft and when I pressed the keys lightly, it was loud. To correct this problem, I had to "reinitialize" it.
What this does is resets the computer inside the instrument back to the factory default settings. You will lose any settings you have changed, but it needs to be done from time to time. After you reinitialize, you may need to reconfigure the instrument for MIDI. This function has saved me many times. Although, I've been using my Roland Fantom X8 for over 2 years with 200+ shows and never once have had to reinitialize it!
Last Resort (sometimes can be a first resort)
Try turning the power off to everything then back on again. This trick works especially with cheaper keyboards such as the ones with speakers built into them (like a low cost Casio). They seem to have the biggest problem with freezing up. Once in a great while, the more expensive gear will freeze up.
Keep in mind, it is also a computer, and every computer I have ever spent any time on has eventually crashed. That's not because of me though, of course not... When I was in college, the MIDI lab had a lot of static. Quite often when you would touch the MIDI keyboards in the lab and accidentally shock one, it would freeze up. So we had to restart it and then it was fine.
Call for MIDI Help
Most good computer software companies offer free technical support to their registered customers. Contact them and see what they have to say. The manufacturer of your MIDI instruments may also offer free technical support. You can also try going to their websites to see if they have online technical support. I have also found online forums to be extremely helpful.