Roland D-20 diagnostic mode

To do that you have to hold Exit + Edit.

And on Exit + Tune/Function try to move bender and value knob.

It's a midi sequence.follow my guide how to put it.You need to connect it to a MIDI cable.If you don't have a port to connect it you will need to buy a MIDI to USB.And you need a MIDI cable.Those plugs on back of the D-20,you will see something like this:

____MIDI____
Thru Out In

There you need to connect those cables.You don't need any flash drive.

Link to download GM set for D-20
here it is.

http://www.mediafire.com/?njmzdjtj5z3

There are few more secrets.For example:To completely reset the synth,you have to hold write + tune/function.To see the ROM version,you have to hold Edit + Data Transfer.

Forgot to tell you that you can test bender and value knob on Exit + Tune/Function and PCM Wave on Exit + Compare by clicking Bank buttons.

while powering up. Then over there see if there is any problem.Exit + Multi timbral to enter are the tests.