Archive: Roland D-20 Main Board Error

10. May 2010

I feel like I'm creating a series of DIY articles here about recouping your investment from twenty-some years ago.

Actually, I have heard from several people on my previous article on the D-20 backup battery change, so I figured I would post this tip as well since there are precious few resources for older electronic instruments, and even less for this venerable keyboard.

I was recently looking around online and found a great resource, a freeware SysEx Librarian program for Macintosh OS X (http://www.snoize.com/SysExLibrarian/). I use an old Macintosh Powerbook running OS X 10.4 and an Edirol UM-2ex MIDI/USB interface for swapping out kit sets on my Roland TDW-10 setup with VDrumLib. So I had visions of being able to do the same thing with my D-20 patches and tones, which seemed pretty convenient.

I went through the whole SysEx load on the keyboard after turning memory protect off, and after it finished, the keyboard was locked up. I turned it off and tried turning it back on. It started up, and then the display screen went dark. Not blank, but dark. I attempted a reset/initialize by holding down the TUNE/FUNCTION and WRITE buttons on startup, but after the initial startup screen on the keyboard it displayed something troubling:

"MAIN BOARD ERROR"

My first piece of advice: don't panic. You can try another restart, but it will probably yield the same dark display screen. What's going on?

The problem is that if you have a D-20 model with a ROM version of 1.03 or less, when attempting a SysEx dump you will have this lock-up and will have to jump through a few hoops to fix it, which I will outline below.

You will have to open up your D-20 and remove the backup battery. You will find instructions and some warnings on this in my article on removing the backup battery. What's happening is that the keyboard is experiencing an error that locks it up, but it is such a serious error that the backup battery actually preserves the bad data in the keyboard memory which perpetuates the error. Removing the backup battery clears this and breaks the error loop. Leave the keyboard without the battery for 5 minutes or so to make sure it does clear the memory. Please also be sure that you have the keyboard unplugged before taking the bottom off.

After you replace the backup battery and replace the bottom cover, plug it in and hold down the TUNE/FUNCTION and WRITE buttons when you turn it on. The keyboard will initialize to its initial "New Out of the Box" state and you will be able to perform a restore of your settings, tones, timbres and patches, which you will need to do since the memory has been wiped by removing all power for the backup for the keyboard.

To safely transfer MIDI dump info to the D-20 with an earlier ROM chip, you will need to use the "ONE-WAY BULK RECEIVE ALL DATA TRANSFER" mode on the keyboard. Check the manual on this one...it's not difficult, but it is an extra couple steps compared to modern plug & play.

So there is still hope. Incidentally, here are all the combinations of startup modes that you can initiate by holding down function buttons as you turn the synth on:

TUNE/FUNCTION + WRITE: initialize the D-20

EXIT + EDIT: memory test

EXIT + TUNE/FUNCTION: controller test - shows bender value, etc.

EXIT + MIDI: keyboard test - shows key and velocity

EXIT + COMPARE: D/A adjust and PCM test; band buttons play PCM sounds for D/A setup

EXIT + ENTER: lamp test - all the lights blink

EXIT + PERFORMANCE/MULTI-TIMBRAL: floppy disk test